# Endangered and Threatened Wildlife and Plants; California Spotted Owl; Endangered Status for the Coastal-Southern California Distinct Population Segment and Threatened Status With Section 4(d) Rule for the Sierra Nevada Distinct Population Segment

> Briefs, arguments, decisions, and more.

URL: https://www.frixlaw.com/law-library/documents/fr%3A2023-03526

## Record

- **Collection:** Federal Register
- **Document type:** Proposed Rule
- **Published:** February 23, 2023
- **Citation:** 88 FR 11600

## Text

DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R8-ES-2022-0166; FF09E21000 FXES1111090FEDR 234]
RIN 1018-BG64
Endangered and Threatened Wildlife and Plants; California Spotted Owl; Endangered Status for the Coastal-Southern California Distinct Population Segment and Threatened Status With Section 4(d) Rule for the Sierra Nevada Distinct Population Segment

AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Proposed rule.

SUMMARY:

We, the U.S. Fish and Wildlife Service (Service), propose to list two distinct population segments (DPSs) of the California spotted owl (
Strix occidentalis occidentalis
), a bird species from California and Nevada, under the Endangered Species Act of 1973, as amended (Act). This determination also serves as our 12-month finding on a petition to list the California spotted owl. After a review of the best available scientific and commercial information, we find that listing the Coastal-Southern California DPS as endangered is warranted, and that listing the Sierra Nevada DPS as threatened is warranted. Accordingly, we propose to list the Coastal-Southern California DPS as an endangered species under the Act and the Sierra Nevada DPS as a threatened species with a rule issued under section 4(d) of the Act (“4(d) rule”). If we finalize this rule as proposed, it will add these two DPSs to the List of Endangered and Threatened Wildlife and extend the Act's protections to them.

DATES:

We will accept comments received or postmarked on or before April 24, 2023. Comments submitted electronically using the Federal eRulemaking Portal (see
ADDRESSES
, below) must be received by 11:59 p.m. eastern time on the closing date. We must receive requests for a public hearing, in writing, at the address shown in
FOR FURTHER INFORMATION CONTACT
by April 10, 2023.

ADDRESSES:

Written comments:
You may submit comments by one of the following methods:

(1)
Electronically:
Go to the Federal eRulemaking Portal:
https://www.regulations.gov.
In the Search box, enter FWS-R8-ES-2022-0166, which is the docket number for this rulemaking. Then, click on the Search button. On the resulting page, in the panel on the left side of the screen, under the Document Type heading, check the Proposed Rule box to locate this document. You may submit a comment by clicking on “Comment.”

(2)
By hard copy:
Submit by U.S. mail to: Public Comments Processing, Attn: FWS-R8-ES-2022-0166, U.S. Fish and Wildlife Service, MS: PRB/3W, 5275 Leesburg Pike, Falls Church, VA 22041-3803.

We request that you send comments only by the methods described above. We will post all comments on
https://www.regulations.gov.
This generally means that we will post any personal information you provide us (see Information Requested, below, for more information).

Availability of supporting materials:
Supporting materials, such as the species status assessment report, are available at
https://www.regulations.gov
under Docket No. FWS-R8-ES-2022-0166.

FOR FURTHER INFORMATION CONTACT:

Michael Fris, Field Supervisor, Sacramento Fish and Wildlife Office, 2800 Cottage Way, Sacramento, CA 95825; telephone 916-414-6700. Individuals in the United States who are deaf, deafblind, hard of hearing, or have a speech disability may dial 711 (TTY, TDD, or TeleBraille) to access telecommunications relay services. Individuals outside the United States should use the relay services offered within their country to make international calls to the point-of-contact in the United States.

SUPPLEMENTARY INFORMATION:

Executive Summary

Why we need to publish a rule.
Under the Act, a species warrants listing if it meets the definition of an endangered species (in danger of extinction throughout all or a significant portion of its range) or a threatened species (likely to become endangered within the foreseeable future throughout all or a significant portion of its range). If we determine that a species warrants listing, we must list the species promptly and designate the species' critical habitat to the maximum extent prudent and determinable. We have determined that the Sierra Nevada DPS of the California spotted owl meets the definition of a threatened species, and the Coastal-Southern California DPS of the California spotted owl meets the definition of an endangered species; therefore, we are proposing to list them as such. Listing a species as an endangered or threatened species can be completed only by issuing a rule through the Administrative Procedure Act rulemaking process (5 U.S.C. 551
et seq.
).

What this document does.
We propose the listing of the Sierra Nevada DPS of the California spotted owl as a threatened species with a rule under section 4(d) of the Act and the Coastal-Southern California DPS of the California spotted owl as an endangered species under the Act.

The basis for our action.
Under the Act, we may determine that a species is an endangered or threatened species because of any of five factors: (A) The present or threatened destruction, modification, or curtailment of its habitat or range; (B) overutilization for commercial, recreational, scientific, or educational purposes; (C) disease or predation; (D) the inadequacy of existing regulatory mechanisms; or (E) other natural or manmade factors affecting its continued existence.

We have determined that both the Sierra Nevada population and the coastal-southern California population of the California spotted owl are discrete and significant under our DPS policy and are, therefore, listable entities under the Act. The Sierra Nevada DPS is found in the Sierra Nevada Mountain Ranges and foothills in California and western Nevada. The Coastal-Southern California DPS is found in the Coast, Transverse, and Peninsular Ranges of California. These two DPSs together represent the entirety of the California spotted owl's range.

The Sierra Nevada DPS of the California spotted owl is currently being impacted by high-severity fire, tree mortality, drought, and barred owls. This DPS still has resiliency throughout its range, and some areas remain in stable condition; however, we expect the magnitude of impacts from high-severity fire, tree mortality, drought, climate change, and other threats to increase into the future. Because the Sierra Nevada DPS is likely to become in danger of extinction within the foreseeable future, we propose to list it as threatened.

The Coastal-Southern California DPS has low resiliency, redundancy, and representation. The entirety of the range of this DPS is at extremely high risk of fire, and available habitat is fragmented. All areas of the Coastal-Southern California DPS are currently declining, and the DPS faces additional threats from tree mortality and drought. Because the Coastal-Southern California DPS is currently in danger of extinction, we propose to list it as endangered.

Information Requested

We intend that any final action resulting from this proposed rule will be based on the best scientific and commercial data available and be as accurate and as effective as possible. Therefore, we request comments or information from other governmental agencies, Native American Tribes, the scientific community, industry, or any other interested parties concerning this proposed rule.

We particularly seek comments concerning:

(1) The species' biology, range, and population trends, including:

(a) Biological or ecological requirements of the species, including habitat requirements for feeding, breeding, and sheltering;

(b) Genetics and taxonomy;

(c) Historical and current range, including distribution patterns and the locations of any additional populations of this species;

(d) Historical and current population levels, and current and projected trends; and

(e) Past and ongoing conservation measures for the species, its habitat, or both.

(2) Factors that may affect the continued existence of the species, which may include habitat modification or destruction, overutilization, disease, predation, the inadequacy of existing regulatory mechanisms, or other natural or manmade factors.

(3) Biological, commercial trade, or other relevant data concerning any threats (or lack thereof) to this species and existing regulations that may be addressing those threats.

(4) Additional information concerning the historical and current status of this species.

(5) Information on regulations that may be necessary and advisable to provide for the conservation of the Sierra Nevada DPS of the California spotted owl and that we can consider in developing a 4(d) rule for the species. In particular, information concerning the extent to which we should include any of the section 9 prohibitions in the 4(d) rule or whether we should consider any additional exceptions from the prohibitions in the 4(d) rule.

(6) Whether we should include in our 4(d) rule for the Sierra Nevada DPS the provision at 50 CFR 17.7 for raptors in captivity.

(7) Which areas may be appropriate as critical habitat for the species and why areas should or should not be proposed for designation as critical habitat in the future, including whether there are threats to the species from human activity that would be expected to increase due to the designation and whether that increase in threat would outweigh the benefit of designation such that the designation of critical habitat may not be prudent.

(8) Specific information on:

(a) The amount and distribution of habitat for the Sierra Nevada DPS and the Coastal-Southern California DPS of the California spotted owl which should be considered for proposed critical habitat;

(b) What may constitute the physical or biological features essential to the conservation of the species within the geographical range currently occupied by the species;

(c) Where these features are currently found;

(d) Whether any of these features may require special management considerations or protection;

(e) What areas are currently occupied and contain features essential to the conservation of the species that should be included in the designation and why; and

(f) What unoccupied areas may be essential for the conservation of the species and why.

Please include sufficient information, such as scientific journal articles or other publications, to allow us to verify any scientific or commercial information you include.

Please note that submissions merely stating support for, or opposition to, the action under consideration without providing supporting information, although noted, do not provide substantial information necessary to support a determination. Section 4(b)(1)(A) of the Act (16 U.S.C. 1533(b)(1)(A)) directs that determinations as to whether any species is an endangered or a threatened species must be made solely on the basis of the best scientific and commercial data available.

You may submit your comments and materials concerning this proposed rule by one of the methods listed in
ADDRESSES
. We request that you send comments only by the methods described in
ADDRESSES
.

If you submit information via
https://www.regulations.gov,
your entire submission—including any personal identifying information—will be posted on the website. If your submission is made via a hardcopy that includes personal identifying information, you may request at the top of your document that we withhold this information from public review. However, we cannot guarantee that we will be able to do so. We will post all hardcopy submissions on
https://www.regulations.gov.

Comments and materials we receive, as well as supporting documentation we used in preparing this proposed rule, will be available for public inspection on
https://www.regulations.gov.

Because we will consider all comments and information we receive during the comment period, our final determinations may differ from this proposal. Based on the new information we receive (and any comments on that new information), we may conclude that the Coastal-Southern California DPS is threatened instead of endangered, or that the Sierra Nevada DPS is endangered instead of threatened, or we may conclude that neither DPS warrants listing as either an endangered species or a threatened species. In addition, we may change the parameters of the prohibitions or the exceptions to those prohibitions in the 4(d) rule for the Sierra Nevada DPS if we conclude it is appropriate in light of comments and new information received. For example, we may expand the incidental-take prohibitions or the exceptions to those prohibitions in the 4(d) rule for the Sierra Nevada DPS to include prohibiting additional activities if we conclude that those additional activities are not compatible with conservation of the DPS. Conversely, we may establish additional exceptions to the incidental-take prohibitions in the final rule if we conclude that the activities would facilitate or are compatible with the conservation and recovery of the DPS.

Public Hearing

Section 4(b)(5) of the Act (16 U.S.C. 1533(b)(5)) provides for a public hearing on this proposal, if requested. Requests must be received by the date specified in
DATES
. Such requests must be sent to the address shown in
FOR FURTHER INFORMATION CONTACT
. We will schedule a public hearing on this proposal, if requested, and announce the date, time, and place of the hearing, as well as how to obtain reasonable accommodations, in the
Federal Register
and local newspapers at least 15 days before the hearing. We may hold the public hearing in person or virtually via webinar. We will announce any public hearing on our website, in addition to the
Federal Register
. The use of virtual public hearings is consistent with our regulations at 50 CFR 424.16(c)(3).

List of Abbreviations and Acronyms

We use many abbreviations and acronyms in this proposed rule. For the convenience of the reader, we define some of them here:

ac = acres

BLM = Bureau of Land Management

CAL FIRE = California Department of Forestry and Fire Protection

CDWR = California Department of Water Resources

CI = confidence interval

cm = centimeters

dbh = diameter at breast height

DPS = distinct population segment

ft = feet

HCP = habitat conservation plan

ha = hectares

in = inches

km = kilometers

IPCC = Intergovernmental Panel on Climate Change

m = meters

mi = miles

MOU = memorandum of understanding

NPS = National Park Service

PAC = protected activity center

RCP = representative concentration pathway

SPI = Sierra Pacific Industries

SSA = species status assessment

USFS = U.S. Forest Service

Previous Federal Actions

For a detailed history of prior petitions, listing actions, and litigation, please see the 12-month finding published on May 24, 2006 (71 FR 29886). Subsequent to that finding, we were petitioned twice to list the California spotted owl as endangered or threatened and to designate its critical habitat under the Act (16 U.S.C. 1531
et seq.
). The first petition was submitted in December 2014, by the Wild Nature Institute and John Muir Project of Earth Island Institute, and the second in August 2015, by Sierra Forest Legacy and Defenders of Wildlife. On September 18, 2015, we published a 90-day finding that the petitions presented substantial scientific or commercial information indicating that listing may be warranted for the California spotted owl (80 FR 56423). On November 8, 2019, we published a 12-month finding that listing the California spotted owl was not warranted at that time (84 FR 60371).

In August 2020, Sierra Forest Legacy, Defenders of Wildlife, and the Center for Biological Diversity filed a complaint challenging our 12-month not-warranted finding. By stipulated settlement agreement approved by the court on November 30, 2021, we agreed to submit to the
Federal Register
a new 12-month finding for the California spotted owl on or before February 15, 2023 (
Sierra Forest Legacy, et al.
v.
U.S. Fish and Wildlife Service, et al.,
No. 5:20-cv-05800-BLF (N.D. Cal.)). This document serves as our 12-month finding and completes our obligations under that settlement agreement.

Peer Review

In 2022, a species status assessment (SSA) team prepared an SSA report for the California spotted owl. The SSA team was composed of Service biologists, in consultation with other species experts. The SSA report represents a compilation of the best scientific and commercial data available concerning the status of the species, including the impacts of past, present, and future factors (both negative and beneficial) affecting the species.

In accordance with our joint policy on peer review published in the
Federal Register
on July 1, 1994 (59 FR 34270), and our August 22, 2016, memorandum updating and clarifying the role of peer review of listing actions under the Act, we solicited independent scientific review of the information contained in the California spotted owl SSA report. The Service sent the SSA report to four independent peer reviewers and received one response. Results of this structured peer review process can be found at
https://www.regulations.gov.
In preparing this proposed rule, we incorporated the results of these reviews, as appropriate, into the SSA report, which is the foundation for this proposed rule.

Summary of Peer Reviewer Comments

We received comments from one peer reviewer on the draft SSA report. We reviewed all comments we received from the peer reviewer for substantive issues and new information regarding the information contained in the SSA report. The peer reviewer generally provided additional references, clarifications, and suggestions, including further definitions of some of the terms used. We updated the SSA report based on the peer reviewer's comments, including changing the approach to our scoring system for the current and future habitat analyses, clarifying specific points where appropriate, and adding additional details and suggested references where needed. Peer reviewer comments are addressed in the following summary and were incorporated into the SSA report as appropriate.

Comment 1:
The peer reviewer stated that there was not enough discussion in the SSA report about how habitat factors have been observed to impact owls, particularly in regards to the existing studies analyzing demographic trends of California spotted owls. Further, the peer reviewer stated that the SSA report should discuss the methodology used in the demography studies.

Our response:
We acknowledge that habitat factors and demographic factors are interrelated, and that understanding the relation between those two issues is crucial. We discuss how habitat factors influence demographic factors, and vice versa, in sections 3.1 and 3.2 of the SSA report (Service 2022, pp. 14-24). We have also incorporated all available information on how the two are related. Additionally, not all of the demographic studies discuss the relationship between vital rates or population trends and habitat factors, but we incorporated the information into the SSA report where available.

Regarding the methodology used in the demography studies, we added a paragraph to the SSA report that discusses different methodologies used in the different types of population studies available in the literature (Service 2022, p. 24). We will provide a list of all literature cited should any readers wish to review those studies in more detail, and we will provide any studies not readily available on
https://www.regulations.gov.

Comment 2:
The peer reviewer further questioned the assumption in the SSA report that high-quality habitat is equivalent to population stability, or vice versa.

Our response:
While we recognize that data are limited, the best available scientific and commercial data, including all available information on habitat use and species needs for the California spotted owl, concluded that the relationship between high-quality habitat and population stability is sufficiently certain to rely upon for our analysis of species viability.

Comment 3:
While recognizing that some protected activity center (PAC) information is out of date, the peer reviewer suggested adding the amount of PAC area to the analysis units in section 5.3 of the SSA report.

Our response:
The detailed analysis unit descriptions describe the current condition of each unit. Because PAC information does not provide insight on the current condition of each analysis unit, it would not be appropriate to include in section 5.3 of the SSA report (a PAC is a designation made by the USFS to protect the best available 121 ha (300 ac) of habitat in as compact of a unit as possible around a nest tree). We do, however, incorporate information from PACs throughout the SSA report and this proposed rule to understand the impact, breadth, and distribution of threats across the landscape.

Comment 4:
The peer reviewer questioned whether we should use the same criteria to analyze conditions in the Sierra Nevada and in coastal/southern California.

Our response:
In order to present a standardized comparison across all analysis units, we used the same scoring criteria for the Sierra Nevada and

coastal/southern California. However, we recognize that California spotted owls may use different-sized trees in the coastal-southern California population than in the Sierra Nevada population. We presented a separate analysis acknowledging this, and we included the difference in tree sizes found in the two geographic areas (Service 2022, tables 9, 13, and 18).

I. Proposed Listing Determination

Background

A thorough review of the taxonomy, life history, and ecology of the California spotted owl (
Strix occidentalis occidentalis
) is presented in the SSA report (version 2.0; Service 2022, pp. 8-14).

California spotted owls are medium-sized brown owls measuring 46.6-48.3 cm (18.3-19.0 in) with a mottled appearance, round face, large pale brown facial disks, dark brown eyes, and a yellowish green bill (Verner et al. 1992, p. 55; Gutiérrez et al. 2020, “Appearance” section). Females are generally slightly larger than males (Verner et al. 1992, p. 55).

The American Ornithological Society (formerly the American Ornithologists' Union (AOU)) currently recognizes three distinct subspecies of spotted owls: northern spotted owl (
Strix occidentalis caurina
), California spotted owl, and Mexican spotted owl (
Strix occidentalis lucida
) (AOU 1957). Given similarities between the subspecies of spotted owls, the SSA report and this proposed rule use available relevant literature for both the northern spotted owl and the Mexican spotted owl as necessary and appropriate and clearly identify when we refer to those entities. The term “spotted owl” is used when talking about
Strix occidentalis
as a whole. Additionally, under the Act, the term “species” includes any subspecies of fish or wildlife or plants. For the purposes of this proposed rule, we in general use “species” to refer to the California spotted owl rather than “subspecies.”

There is some overlap in range between northern spotted owls and the California spotted owl, and interbreeding between the two subspecies occasionally occurs (Haig et al. 2004, p. 690; Barrowclough et al. 2011, pp. 581, 583-586; Miller et al. 2017, pp. 6871, 6875-6877; Hanna et al. 2018, pp. 3947-3948, 3950-3951). California spotted owls have the lowest genetic diversity among the subspecies compared to northern and Mexican spotted owls, suggesting that the California spotted owl is of more recent origin than the other spotted owl subspecies or that populations of the California spotted owl are much smaller than the northern and Mexican spotted owl populations (Barrowclough et al. 1999, pp. 919, 927; Haig et al. 2004, p. 683). Within the California spotted owl, genetic differences between individuals found in the Sierra Nevada and individuals found in mountain ranges throughout southern California suggest limited interbreeding between these two areas (Barrowclough et al. 2005, pp. 1113-1114; Hanna et al. 2018, pp. 3947-3948, 3950). However, these genetic studies are limited by sample size and sampling locations. We are only aware of one study that includes California spotted owls from coastal California; this study shows gene flow between geographically adjacent spotted owl samples, with some evidence of asymmetrical gene flow between California spotted owls in Carmel, California (coastal California), and the Sierra Nevada (Barrowclough et al. 2005, p. 1114).

California spotted owls are distributed across habitat in California and Nevada including the Sierra Nevada, coastal California, and southern California. The California spotted owl has also been documented in the Sierra San Pedro Martir mountains in Baja California Norte, Mexico, with a few scattered records of the spotted owl in Baja California between 1887 and 1972 (Grinnell 1928, p. 242; Wilbur 1987, p. 170). However, many researchers now question whether the species ever actually occurred in Baja California (Erickson in litt. 2022; Unitt in litt. 2022). There are only a few accounts of the species, with none of those accounts mentioning breeding or evidence of breeding pairs. Therefore, we consider the California spotted owl to be only a rare visitor of Mexico, and do not consider Baja California as its own population.

California spotted owls are continuously distributed throughout the forests of the western side of the Sierra Nevada from Shasta County south to the Tehachapi Pass in Kern County (Gutiérrez et al. 2017, pp. 13-14). They are sparsely distributed on the eastern side of the Sierra Nevada into western Nevada (GBBO 2012, p. Spp-47-4). Outside of the Sierra Nevada, the species' range is not contiguous. Along the California coast and into southern California, the species is found in the Coast, Transverse, and Peninsular mountain ranges from Monterey County in the north to San Diego County in the south (Gutiérrez et al. 2020, “Distribution” section). However, there is a large break in the species' range around San Luis Obispo County, where the species is not known to occur. The Tehachapi Pass between the Sierra Nevada to the east and the Transverse Range to the west represents a gap between California spotted owls in the Sierra Nevada and California spotted owls in coastal and southern California (Verner et al. 1992, p. 4). California spotted owls are absent from the Santa Cruz Mountains (part of the Coast Range) in California, where suitable habitat appears to be present (Gutiérrez et al. 2017, p. 240).

California spotted owls are currently found throughout their known historical range, although there is evidence of a decrease in abundance in parts of the range including both the Sierra Nevada and southern California (Franklin et al. 2004, pp. 23-42; Tempel et al. 2014b, pp. 90-94; Conner et al. 2016, pp. 7-18; Hanna et al. 2018, pp. 3947-3949; Tempel et al. 2022, p. 18). The majority of California spotted owls are found in mid-elevation, mixed-conifer forest on the west slope of the Sierra Nevada (Gutiérrez et al. 2017, p. xviii).

California spotted owls are long-lived (approximately 16-23 years) with high adult survival and low reproductive output (Seamans and Gutiérrez 2007, p. 57; Gutiérrez et al. 2020, “Demography and Populations” section). Pairs exhibit high territory fidelity (Gutiérrez et al. 2020, “Sounds and Vocal Behavior” and “Behavior” sections). Territories—the area actively defended by a breeding pair—can overlap with neighboring pairs and are smaller than home ranges (Gutiérrez et al. 2017, pp. xvi, 294). Estimates of territory size have varied from 203 ha (502 ac) to 813 ha (2,009 ac), with higher estimates in the northern Sierra Nevada and lower estimates in southern California (Bingham and Noon 1997, p. 136; Blakesley et al. 2005, p. 1556; Seamans and Gutiérrez 2007b, p. 568; Tempel et al. 2014b, p. 2091). Higher quality territories measured in adult survival, territory colonization, and territory extinction, tend to have a greater proportion of higher canopy cover (Tempel et al. 2014b, p. 2089; Gutiérrez et al. 2017, pp. 271-273). Home ranges, or areas used by a pair to meet requirements for survival and reproduction, are about 400-1,200 hectares (ha) (1,000-3,000 acres (ac)) in size (Gutiérrez et al. 2017, p. xviii). Home ranges are typically larger in the northern portion of the range (>1,000 ha (2,470 ac)) and smaller in the southern portion of the range (<1,000 ha (2,470 ac)) due to differences in selected prey species (Gutiérrez et al. 2017, p. xviii).

Breeding season begins in mid-February, and the juvenile dependency period can last through mid-September;

nesting generally starts earlier at lower elevations (Gutiérrez et al. 2020, “Breeding” section). During the breeding season, California spotted owls tend to spend the majority of their time at activity centers of around 121 ha (299 ac) (Verner et al. 1992, p. 87; Berigan et al. 2012, p. 299). Activity centers are the areas where California spotted owls they nest, roost, and forage (Verner et al. 1992, p. 87; Gutiérrez et al. 2017, pp. 270-271). Spotted owls typically have only one nest per breeding season, and they rarely re-nest if the first nests fails (Gutiérrez et al. 2020, “Breeding” section). Females typically lay 1-3 eggs, with survival of offspring into adulthood highest when two young fledge in comparison to singletons and triplets (Peery and Gutiérrez 2013, p. 132; Gutiérrez et al. 2020, “Demography and Populations” section). Although difficult to estimate due to dispersal, juvenile survival in California spotted owls is low (Blakesley et al. 2001, p. 667; LaHaye et al. 2004, p. 1056).

Spotted owls always disperse from their natal areas in the year they hatch. Natal dispersal occurs during the fall, after juveniles have reached adult weight and parental care stops (Gutiérrez et al. 2020, “Breeding” section). Average juvenile dispersal in southern California is 9.7-11.3 km (6-7 mi), and ranges from 3.2-37.0 km (2-23 mi) (LaHaye et al. 2001, p. 691). Larger dispersal distances, up to 177 km (110 mi), have been documented in both northern and Mexican subspecies (Gutiérrez and Carey 1985, p. 60; Ganey et al. 1998, p. 206; Hollenbeck et al. 2018, p. 533). Adult California spotted owls typically do not shift territories or undergo breeding dispersal from an established territory (Blakesley et al. 2006, p. 76; Zimmerman et al. 2007, p. 963; Gutiérrez et al. 2011, p. 592); however, some breeding dispersal occurs in adults or pairs that have been unsuccessful in mating or if habitat is altered (Blakesley et al. 2006, p. 71).

Breeding only occurs once a pair is formed and settled into a territory (Gutiérrez et al. 2017, p. 15). Pairs can breed in consecutive years, but in certain conditions may postpone reproduction until temporarily poor environmental conditions improve (Stearns 1976, pp. 4, 15-26; Franklin et al. 2000, p. 539; Gutiérrez et al. 2017, p. xvi). The number of young fledged annually per territorial California spotted owl female in several areas within the Sierra Nevada ranged from 0.478-0.988 (Blakesley et al. 2010, pp. 1, 18).

In general, California spotted owls nest in areas of mature, multistoried forests with complex structure, larger trees, multi-layered high canopy cover, and large amounts of coarse woody debris, while areas with higher heterogeneity of forest types and the edges between them are important for foraging (Gutiérrez et al. 2017, p. xvii). In the Sierra Nevada, a majority of California spotted owls occur within mid-elevation ponderosa pine (
Pinus ponderosa
), mixed-conifer, white fir (
Abies concolor
), and mixed-evergreen forest types, with few occurring in the lower elevation oak woodlands of the western foothills (Gutiérrez et al. 2017, p. 109). In coastal and southern California, California spotted owls are found in riparian/hardwood forests and woodlands, live oak/big cone fir forests, and redwood/California laurel forests (Gutiérrez et al. 2017, p. xxvi). In southern California, vegetation types differ relative to the Sierra Nevada, and what is considered a large tree in southern California may not be comparable to what is considered a large tree in the Sierra Nevada. However, California spotted owls in southern California still select for territories containing larger trees (LaHaye et al. 1997, pp. 42, 47) and predominantly closed canopy cover (Smith et al. 2002, pp. 137, 142, 144).

California spotted owls can use a variety of habitat types for nesting. At higher elevations, the species primarily uses conifers, and as elevations decrease, they increasingly use hardwoods (Gutiérrez et al. 2020, “Habitat” section). Important components of nesting habitat include high canopy cover, larger trees, and high habitat heterogeneity. For nest trees, California spotted owls use a subset of larger trees or snags, with the average nest tree measuring 124 cm (49 in) diameter at breast height (dbh) and 31 m (103 ft) tall in the Sierra Nevada (Gutiérrez et al. 2017, p. 50). In southern California, California spotted owls use cavity, broken-top, and platform nests with different characteristics (LaHaye et al. 1997, pp. 42, 47; Tanner 2022, pers. comm.). In southern California, California spotted owl use of platform or old raptor nests is more common; thus, owls with these types of nests were observed using smaller trees than used in other nest types (LaHaye et al. 1997, p. 45). Within their nesting territory, California spotted owls select for nest sites farther away from the forest edge (Phillips et al. 2010, p. 312). Overall, California spotted owl occupancy, colonization, adult survival, and reproductive success are all positively associated with an increasing amount of structurally complex habitat on the landscape (Franklin et al. 2000, p. 578; Blakesley et al. 2005, p. 1562; Tempel et al. 2014a, pp. 2103-2104).

California spotted owls can also use a variety of habitats to forage. California spotted owls primarily prey upon a variety of small to medium-sized mammals, including, but not limited to, flying squirrels, woodrats, and pocket gophers, as well as birds, lizards, and insects (Gutiérrez et al. 2017, p. 28). In the Sierra Nevada, above approximately 1,200 m (3,937 ft) in coniferous forests, California spotted owls most commonly consume Humboldt's flying squirrels (
Glaucomys oregonensis
) (Laymon 1988, pp. 130-154; Verner et al. 1992, pp. 4, 65-69; Munton et al. 2002, pp. 99, 101-104). Preferred habitat conditions of Humboldt's flying squirrels include cool, moist, mature forest with abundant standing and down snags where they can forage on mostly fungi and lichens (Cassola 2016, p. 3). In lower elevation oak woodlands and riparian-deciduous forests in the Sierra Nevada and southern California, California spotted owls select for woodrats (
Neotoma
spp.) (Verner et al. 1992, pp. 4, 65, 68-69; Smith et al. 1999, pp. 22, 24-28; Munton et al. 2002, pp. 99, 101-104). Due to this elevational gradient in prey distribution, California spotted owls select foraging sites characteristic of flying squirrel habitats at higher elevations and woodrat habitats at lower elevations (Kramer et al. 2021b, pp. 12-14). Some individuals have smaller home ranges where woodrats are the primary prey source, presumably because woodrats have a higher caloric gain per successful foraging event and are found in higher densities than northern flying squirrels (Zabel et al. 1995, pp. 433, 435-438). There is some evidence that California spotted owl diet may shift following wildfires. In national parks in the Sierra Nevada that have implemented longstanding fire management efforts (
i.e.,
prescribed fire and managed wildfire), the California spotted owl diet contains a higher proportion of woodrats and pocket gophers relative to flying squirrels (Hobart et al. 2021, pp. 254, 256).

In regard to foraging habitat, important components include the presence of larger trees, high canopy cover, and coarse woody debris. California spotted owls tend to forage in larger trees, likely due to the canopy cover provided by larger trees and the important resources such as shelter and food that larger trees provide for prey species (Laymon 1988, pp. 47, 71, 77, 100; Verner et al. 1992, pp. 9-10, 60, 88; Moen and Gutiérrez 1997, pp. 1281, 1284). However, California spotted owls use medium-size trees (defined by the authors as >25 cm dbh (9 in)) for

foraging while avoiding areas dominated by small trees (<25 cm dbh (9 in)) (Kramer et al. 2021a, pp. 4, 6). Coarse woody debris is also an important habitat feature for California spotted owls because it provides food, shelter, and protection for prey species, especially woodrats (Waters and Zabel 1995, pp. 861-862; Pyare and Longland 2002, pp. 1016-1017; Innes et al. 2007, pp. 1523, 1526; Kelt et al. 2013, p. 1208). Heterogeneous forests, such as those found on private lands, may provide more habitat for California spotted owls than was previously understood (Atuo et al. 2019, p. 295), as some privately owned study areas have higher numbers of occupied sites than adjacent USFS study areas (Roberts et al. 2017, p. 113).

California spotted owl roosting habitat is very similar to nesting habitat. Specific components of roosting habitat include multi-layered high canopy cover and presence of large trees. It is believed that such forests provide young California spotted owls with protection from predators and from high temperatures. California spotted owls have a low heat tolerance in comparison to other bird species, beginning to show heat stress at 30-34 degrees Celsius (°C) (86-93 degrees Fahrenheit (°F)). The cooler microclimates that multi-layered high canopy cover provides are important for both juveniles and adults during warm summers (Weathers 1981, pp. 358-359; Barrows 1981, pp. 303-305; Weathers et al. 2001, pp. 678-679). Presence of large trees is also important for California spotted owl roosting, as individuals tend to roost in large trees, likely due to the canopy cover provided by large trees and the resources they provide for prey species (Laymon 1988, pp. 47, 71, 77, 100; Verner et al. 1992, pp. 9-10, 60, 88; Moen and Gutiérrez 1997, pp. 1281-1284).

Within the SSA report and this proposed rule, we define a population as a group of interbreeding California spotted owls that are more likely to breed among that group than outside of that group. We use information from genetic studies and habitat features to identify two California spotted owl populations: one in the Sierra Nevada, and another in coastal and southern California (hereafter referred to as the coastal-southern California population).

In the western Sierra Nevada, habitat is relatively continuous, without significant gaps in distribution (Gutiérrez et al. 2017, p. xviii); however, in the eastern Sierra Nevada, habitat is more discontinuous with disjunct patches (Dilts 2022, pp. 5-9). Despite this fragmentation, California spotted owls still have substantial gene flow within the Sierra Nevada. However, there is limited gene flow to coastal or southern California, and large-scale fragmentation of suitable habitat divides the Sierra Nevada from this other population (Barrowclough et al. 2005, pp. 1114-1116). We are not aware of specific information about individual California spotted owls moving between these two population areas.

In coastal and southern California, the California spotted owl population consists of subpopulations distributed among discrete mountain ranges, resulting in habitat “islands” surrounded by unsuitable habitat (Verner et al. 1992, p. 187). Areas between these habitat islands are typically lowland desert scrub and chaparral that is unsuitable for California spotted owls, or substantially modified by human-induced development and fragmentation (Verner et al. 1992, p. 187). Some of the subpopulations are separated by relatively narrow gaps, such as the gap between the San Gabriel and San Bernardino Mountains, while other gaps are more significant, such as the gap between the Northern and Southern Santa Lucia Mountains. California spotted owls in coastal and southern California are less well-studied than those in the Sierra Nevada, but there is a notable lack of documented California spotted owl movement between the coastal and southern subpopulations, and we are not aware of any dispersal between them. This population is also described in the literature as being a presumed metapopulation (Verner et al. 1992, pp. 187-206; LaHaye et al. 1994, entire; Gutiérrez et al. 2017, p. 241) despite the documented lack of connectivity, even though dispersal among populations is a defining characteristic of a metapopulation (see Hanski and Gilpin 1991 for more on metapopulation theory). However, spatial structure of a metapopulation within and among subpopulations is critical for metapopulation functioning, and available evidence does not document successful dispersal between the San Bernardino, San Gabriel, and San Jacinto Mountains, which are adjacent mountain ranges, indicating that if mixing does occur it is very rare (LaHaye et al. 2001, entire; LaHaye et al. 2004, entire; Gutiérrez et al. 2017, pp. 242, 250). Further, not all subpopulations within the metapopulation have equal likelihood of “blinking out” or being rescued/recolonized by other subpopulations, which are important components of metapopulation theory (Gutiérrez et al. 2017, pp. 241-242, 250). Within the coastal-southern California population, the subpopulation inhabiting the San Bernardino and San Gabriel mountains is the largest subpopulation and is the subject of most ecological studies. The persistence of this subpopulation has been identified as important for persistence of the coastal-southern California population (Verner et al. 1992, pp. 197-206).

To conduct a more focused analysis of how different portions of each of the populations' ranges contribute to that population's overall resiliency, we further divided the Sierra Nevada and southern California populations into analysis units (see figure 1, below). We chose analysis units roughly based on public land management boundaries because of varying demographic data and management strategies across the range. Dividing the population up into analysis units based on land management boundaries allows a better assessment of the varying conditions across the range. We identified a total of 15 analysis units: Lassen, Plumas, Tahoe, Eldorado, Humboldt-Toiyabe, Stanislaus, Yosemite, Sierra, Sequoia-Kings Canyon, Sequoia, Inyo, Las Padres, Las Padres-Angeles, San Bernardino, and Cleveland.

BILLING CODE 4333-15-P

EP23FE23.008

Figure 1—Populations and Analysis Units of the California Spotted Owl (CSO)

BILLING CODE 4333-15-C
Distinct Population Segment Evaluation

Under the Act, the term “species” includes any subspecies of fish or wildlife or plants, and any distinct population segment of any species of vertebrate fish or wildlife which interbreeds when mature (16 U.S.C. 1532(16)). To guide the implementation of the DPS provisions of the Act, we and the National Marine Fisheries Service (National Oceanic and Atmospheric Administration—Fisheries), published the Policy Regarding the Recognition of Distinct Vertebrate Population Segments Under the Endangered Species Act (DPS Policy) in the
Federal Register
on February 7, 1996 (61 FR 4722). Under our DPS Policy, we use two elements to assess whether a population segment under consideration for listing may be recognized as a DPS: (1) The population segment's discreteness from the remainder of the species to which it belongs, and (2) the significance of the population segment to the species to which it belongs. If we determine that a population segment being considered for listing is a DPS, then the population

segment's conservation status is evaluated based on the five listing factors established by the Act to determine if listing it as either endangered or threatened is warranted.

As discussed above in Previous Federal Actions, we were petitioned to list the California spotted owl subspecies throughout its range. In response to the petitions, we divided the species into two populations and our analysis covers the full range of the species. Under the Act, we have the authority to consider for listing any species, subspecies, or, for vertebrates, any distinct populations segment of these taxa if there is sufficient information to indicate that such action may be warranted. Therefore, we considered whether the two populations of the California spotted owl (the Sierra Nevada portion of the California spotted owl's range, and the coastal and southern California portions of the California spotted owl's range) meet the DPS criteria under the Act. These two populations comprise the entirety of the California spotted owl's range (and thus the entirety of the petitioned entity), and we have determined that it is appropriate to analyze them individually under our DPS policy.

Discreteness

Under our DPS Policy, a population segment of a vertebrate taxon may be considered discrete if it satisfies either of the following conditions: (1) It is markedly separated from other populations of the same taxon as a consequence of physical, physiological, ecological, or behavioral factors. Quantitative measures of genetic or morphological discontinuity may provide evidence of this separation; or (2) it is delimited by international governmental boundaries within which differences in control of exploitation, management of habitat, conservation status, or regulatory mechanisms exist that are significant in light of section 4(a)(1)(D) of the Act.

We conclude the two segments satisfy the “markedly separate” condition. The Sierra Nevada part of the range is separated from the coastal and southern California parts of the range by large-scale fragmentation of suitable habitat, with the Tehachapi Pass in Kern County identified as the dividing line between these areas (Verner et al. 1992, p. 4; Barrowclough et al. 2005, pp. 1114-1116). The distance between suitable habitat in the closest parts of the Sierra Nevada and the Transverse Range of southern California is only 40 km (25 mi). Although this distance is near the known average dispersal of juvenile California spotted owls, we are not aware of specific information about individual California spotted owls moving between the Sierra Nevada and California spotted owl habitat in coastal and southern California (Service 2022, p. 18).

As discussed above in Background, there are few genetic studies on the California spotted owl. However, existing analyses provide evidence that gene flow between the two parts of the range is limited and may have been restricted to historical asymmetrical gene flow from areas in the central California coast to the Sierra Nevada (Barrowclough et al. 2005, p. 1113), although the study acknowledges that more data are needed to inform this conclusion. Our DPS policy notes that we do not consider it appropriate to require absolute reproductive isolation as a prerequisite to recognizing a distinct population segment. As the policy states, this would be an impracticably stringent standard, and one that would not be satisfied even by some recognized species that are known to sustain a low frequency of interbreeding with related species.

Therefore, because the two populations are markedly separated from each other, we have determined that both the Sierra Nevada and the coastal and southern California parts of the range both individually meet the condition for discreteness under our DPS Policy.

Significance

Under our DPS Policy, once we have determined that a population segment is discrete, we consider its biological and ecological significance to the larger taxon to which it belongs. This consideration may include, but is not limited to: (1) Evidence of the persistence of the discrete population segment in an ecological setting that is unusual or unique for the taxon, (2) evidence that loss of the population segment would result in a significant gap in the range of the taxon, (3) evidence that the population segment represents the only surviving natural occurrence of a taxon that may be more abundant elsewhere as an introduced population outside its historical range, or (4) evidence that the discrete population segment differs markedly from other populations of the species in its genetic characteristics.

For the California spotted owl, we first considered evidence that loss of a population segment would result in a significant gap in the range of the taxon. As discussed above, the southwestern and northeastern parts of the range are separated by approximately 40 km (25 mi). The loss of the coastal and southern California parts of the range would result in the loss of the entire southwestern part of the species' range and decrease species redundancy and ecological and genetic representation, thus decreasing the species' ability to withstand demographic and environmental stochasticity. The loss of the Sierra Nevada range would result in the loss of 70 percent of the species' range, also reducing the species' ability to withstand demographic and environmental stochasticity. Therefore, the loss of either part of the range would result in a significant gap in the range of the California spotted owl.

We then considered evidence whether either of the discrete population segments occur in an ecological setting that is unusual or unique for the taxon. In the Sierra Nevada, a majority of California spotted owls occur within mid-elevation mixed-conifer and mixed-evergreen forest types, with few occurring in the lower elevation oak woodlands of the western foothills (Gutiérrez et al. 2017, p. 109). As described above, in coastal and southern California, California spotted owls are found in riparian/hardwood forests and woodlands, live oak/big cone fir forests, and redwood/California laurel forests, more so than the mixed-conifer communities (Gutiérrez et al. 2017, p. xxvi). Use of these other communities is specific and unique to owls in these areas. What is considered a large tree in southern California may not be comparable to what is considered a large tree in the Sierra Nevada. California spotted owls use a subset of larger trees or snags as their nest trees, with the average nest tree measuring 124 cm (49 in) dbh and 31 m (103 ft) tall in the Sierra Nevada (Gutiérrez et al. 2017, p. 50). In southern California, use of platform or old raptor nests is more common; thus, owls with these types of nests were observed using trees as small as 33 cm (13 in) dbh (Tanner 2022, pers. comm.) with mean values of 75.0 cm (29.5 in) dbh (LaHaye et al. 1997, p. 45). Therefore, we conclude that, for the two populations of California spotted owls, each persists in a unique ecological setting for the species.

The evidence that a significant gap in the range of the taxon would result from the loss of either discrete population segment meets the significance criterion of the DPS Policy. Additionally, there is evidence that the coastal and southern California and the Sierra Nevada parts of the range have persisted in a unique ecological setting for the species. Therefore, under the Service's DPS Policy, we find that the Sierra Nevada and the coastal and southern California parts of the California spotted owl's

range are significant to the taxon as a whole.

Distinct Population Segment Conclusion

Our DPS Policy directs us to evaluate the significance of a discrete population in the context of its biological and ecological significance to the remainder of the species to which it belongs. Based on an analysis of the best available scientific and commercial data, we conclude that both parts of the California spotted owl's range are significant, because loss of either part would result in a significant gap in the range of the taxon, and because the population segments represent evidence that both parts of the range have persisted in a unique ecological setting for the species. Therefore, we conclude that both the Sierra Nevada and the coastal and southern California parts of the California spotted owl's range are both discrete and significant under our DPS Policy and are, therefore, uniquely listable entities under the Act.

Based on our DPS Policy (61 FR 4722; February 7, 1996), if a population segment of a vertebrate species is both discrete and significant relative to the taxon as a whole (
i.e.,
it is a distinct population segment), its evaluation for endangered or threatened status will be based on the Act's definition of those terms and a review of the factors enumerated in section 4(a) of the Act. Having found that both parts of the California spotted owl's range meet the definition of a distinct population segment, we evaluate the status of both the Sierra Nevada DPS and the Coastal-Southern California DPS of the California spotted owl to determine whether either meets the definition of an endangered or threatened species under the Act.

Regulatory and Analytical Framework

Regulatory Framework

Section 4 of the Act (16 U.S.C. 1533) and the implementing regulations in title 50 of the Code of Federal Regulations set forth the procedures for determining whether a species is an endangered species or a threatened species, issuing protective regulations for threatened species, and designating critical habitat for endangered and threatened species. In 2019, jointly with the National Marine Fisheries Service, the Service issued a final rule that revised the regulations in 50 CFR part 424 regarding how we add, remove, and reclassify endangered and threatened species and the criteria for designating listed species' critical habitat (84 FR 45020; August 27, 2019). On the same day, the Service also issued final regulations that, for species listed as threatened species after September 26, 2019, eliminated the Service's general protective regulations automatically applying to threatened species the prohibitions that section 9 of the Act applies to endangered species (84 FR 44753; August 27, 2019).

The Act defines an “endangered species” as a species that is in danger of extinction throughout all or a significant portion of its range, and a “threatened species” as a species that is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range. The Act requires that we determine whether any species is an endangered species or a threatened species because of any of the following factors:

(A) The present or threatened destruction, modification, or curtailment of its habitat or range;

(B) Overutilization for commercial, recreational, scientific, or educational purposes;

(C) Disease or predation;

(D) The inadequacy of existing regulatory mechanisms; or

(E) Other natural or manmade factors affecting its continued existence.

These factors represent broad categories of natural or human-caused actions or conditions that could have an effect on a species' continued existence. In evaluating these actions and conditions, we look for those that may have a negative effect on individuals of the species, as well as other actions or conditions that may ameliorate any negative effects or may have positive effects.

We use the term “threat” to refer in general to actions or conditions that are known to or are reasonably likely to negatively affect individuals of a species. The term “threat” includes actions or conditions that have a direct impact on individuals (direct impacts), as well as those that affect individuals through alteration of their habitat or required resources (stressors). The term “threat” may encompass—either together or separately—the source of the action or condition or the action or condition itself.

However, the mere identification of any threat(s) does not necessarily mean that the species meets the statutory definition of an “endangered species” or a “threatened species.” In determining whether a species meets either definition, we must evaluate all identified threats by considering the species' expected response and the effects of the threats—in light of those actions and conditions that will ameliorate the threats—on an individual, population, and species level. We evaluate each threat and its expected effects on the species, then analyze the cumulative effect of all of the threats on the species as a whole. We also consider the cumulative effect of the threats in light of those actions and conditions that will have positive effects on the species, such as any existing regulatory mechanisms or conservation efforts. The Secretary determines whether the species meets the definition of an “endangered species” or a “threatened species” only after conducting this cumulative analysis and describing the expected effect on the species now and in the foreseeable future.

The Act does not define the term “foreseeable future,” which appears in the statutory definition of “threatened species.” Our implementing regulations at 50 CFR 424.11(d) set forth a framework for evaluating the foreseeable future on a case-by-case basis. The term “foreseeable future” extends only so far into the future as we can reasonably determine that both the future threats and the species' responses to those threats are likely. In other words, the foreseeable future is the period of time in which we can make reliable predictions. “Reliable” does not mean “certain”; it means sufficient to provide a reasonable degree of confidence in the prediction. Thus, a prediction is reliable if it is reasonable to depend on it when making decisions.

It is not always possible or necessary to define the foreseeable future as a particular number of years. Analysis of the foreseeable future uses the best scientific and commercial data available and should consider the timeframes applicable to the relevant threats and to the species' likely responses to those threats in view of its life-history characteristics. Data that are typically relevant to assessing the species' biological response include species-specific factors such as lifespan, reproductive rates or productivity, certain behaviors, and other demographic factors.

Analytical Framework

The SSA report documents the results of our comprehensive biological review of the best scientific and commercial data regarding the status of the species, including an assessment of the potential threats to the species. The SSA report does not represent our decision on whether the species should be proposed for listing as an endangered or threatened species under the Act. However, it does provide the scientific basis that informs our regulatory decisions, which involve the further application of standards within the Act

and its implementing regulations and policies.

To assess California spotted owl viability, we used the three conservation biology principles of resiliency, redundancy, and representation (Shaffer and Stein 2000, pp. 306-310). Briefly, resiliency is the ability of the species to withstand environmental and demographic stochasticity (for example, wet or dry, warm or cold years), redundancy is the ability of the species to withstand catastrophic events (for example, droughts, large pollution events), and representation is the ability of the species to adapt to both near-term and long-term changes in its physical and biological environment (for example, climate conditions, pathogens). In general, species viability will increase with increases in resiliency, redundancy, and representation (Smith et al. 2018, p. 306). Using these principles, we identified the species' ecological requirements for survival and reproduction at the individual, population, and species levels, and described the beneficial and risk factors influencing the species' viability.

The SSA process can be categorized into three sequential stages. During the first stage, we evaluated the individual species' life-history needs. The next stage involved an assessment of the historical and current condition of the species' demographics and habitat characteristics, including an explanation of how the species arrived at its current condition. The final stage of the SSA involved making predictions about the species' responses to positive and negative environmental and anthropogenic influences. Throughout all of these stages, we used the best available information to characterize viability as the ability of a species to sustain populations in the wild over time. We use this information to inform our regulatory decision.

The following is a summary of the key results and conclusions from the SSA report (Service 2022, entire); the full SSA report can be found at Docket No. FWS-R8-ES-2022-0166 on
https://www.regulations.gov.

Summary of Biological Status and Threats

In this discussion, we review the biological condition of the California spotted owl and its resources, and the threats that influence the species' current and future condition, in order to assess the species' overall viability and the risks to that viability.

We note that the California spotted owl SSA report discusses California spotted owls at the individual, population, and species level. The SSA does not make any analysis or conclusions with regard to policy decisions, such as DPS findings, and does not include mention of the two populations of the subspecies as DPSs. Instead, the SSA report provides the biological information that our decisionmakers can then use to inform those policy decisions. This proposed rule and its supporting record contain the policy decisions and rationale. Throughout this Summary of Biological Status and Threats discussion, we discuss the coastal-southern California population of California spotted owl, which we identify as the Coastal-Southern California DPS, and the Sierra Nevada population of California spotted owl, which we identify as the Sierra Nevada DPS.

California Spotted Owl Needs

Individual Needs

In this section, we assess the best available information to identify the specific habitat components needed to support individual fitness at all life stages for California spotted owls. Individual owls must have adequate nesting, foraging, and roosting habitat to be successful. For the purpose of the SSA report and this proposed rule, the components of nesting, foraging, and roosting habitat that we considered most significant include canopy cover, larger trees, and habitat heterogeneity. Habitat heterogeneity is important to California spotted owls as it provides protection from predators and extreme weather conditions, variable microclimates, and habitat for different prey species.

We acknowledge that these habitat components are not all-inclusive and there may be other components of nesting, foraging, and roosting habitat that are not being considered (such as prey). We also acknowledge that a history of fire suppression in the western United States, including throughout the range of both the Sierra Nevada DPS and the Coastal-Southern California DPS, has caused many ecological changes that are not fully understood (Mallek et al. 2013, p. 2). However, we chose to focus on habitat components for which there are available spatial data across the range of the species. Further, prey is indirectly considered in our analysis since the primary California spotted owl prey species also select for high canopy cover and coarse woody debris (Waters and Zabel 1995, p. 858), which are considered here as components of habitat heterogeneity. Populations of California spotted owls require the same habitat components as individuals but at larger scales.

Multi-layered, or complex, high canopy cover is considered an important resource for spotted owls because it provides cool shaded microclimates, camouflage and cover for protection from predators and extreme weather conditions, and habitat for prey species (Forsman 1975, pp. 4, 90, 105; Barrows 1981, p. 302; Forsman et al. 1984, p. 5). High canopy cover from tall trees is associated with higher probability of successful prey capture by California spotted owls (Zulla et al. 2022, p. 8) and is an important predictor for California spotted owl nesting habitat (North et al. 2017, pp. 166, 172-175). Multi-layered high canopy cover around the nest tree and in territories is an important factor associated with California spotted owl reproductive success (Hunsaker et al. 2002, pp. 693-699; Blakesley et al. 2005, pp. 1554, 1558-1562). Areas with canopy cover greater than 70 percent are considered optimal for California spotted owl nest sites and occupancy sharply declines when canopy cover is less than 40 percent (Blakesley et al. 2005, p. 1559; Seamans 2005, pp. iii, 90, 100; Seamans and Gutiérrez 2007b, pp. 566, 568; Tempel et al. 2014a, pp. 2089, 2091, 2101; Tempel et al. 2016, pp. 747, 759). Even in southern California where the habitat is naturally more fragmented with less canopy cover available, California spotted owls still select for areas with higher canopy cover relative to what is available (Smith et al. 2002, pp. 142-143). Further, California spotted owls in Yosemite National Park had territory centers with average values of 40 percent canopy cover in burned forests (Schofield et al. 2020, pp. 4-5).

The presence of large trees, defined as trees that are greater than 61 cm (24 in) dbh (Seamans and Gutiérrez 2007b, pp. 566, 571-574; Tempel et al. 2014b, p. 2094; Jones et al. 2018, p. 344), is important for California spotted owl foraging, roosting, and nesting. California spotted owls tend to forage and roost in large trees, likely due to the canopy cover provided by large trees and the important resources such as shelter and food that large trees provide for prey species (Laymon 1988, pp. 47, 71, 77, 100; Verner et al. 1992, pp. 9-10, 60, 88; Moen and Gutiérrez 1997, pp. 1281, 1284). The presence of tall (>48 m (157 ft)) trees, and the canopy cover they provide, is the best predictor for California spotted owl occupancy, and areas with a high density of large trees are considered high-quality habitat (Blakesley et al. 2005, pp. 1554, 1558-1562; North et al. 2017, pp. 166, 171-176). California spotted owls use a

subset of large trees or snags as their nest trees (LaHaye et al. 1997, pp. 42, 47; Blakesley et al. 2005, pp. 1554, 1558-1562; Gutiérrez et al. 2017, p. 50), and the nest tree itself is critical for California spotted owl reproductive success because it provides the space and structure needed for nests, along with protection from predators and inclement weather. California spotted owls do not build their own nests but rely on larger trees that provide multi-layered high canopy cover with open cavities (created as a result of fallen branches, woodpeckers, etc.), broken tops, platforms, and old raptor nests (Gutiérrez et al. 2020, “Habitat” and “Breeding” sections). The nest tree chosen within a territory is typically one of the oldest and largest live or dead trees within the nesting territory with many defects like cracks, disease scars, or decaying wood (Verner et al. 1992, pp. 6, 60, 71; North et al. 2000, p. 797).

The preferential use of mature forests with high canopy cover and large trees is well-known for California spotted owls (Gutiérrez et al. 2017, p. iii). However, there have been several recent studies showing the importance of other habitat types, habitat edges, and habitat heterogeneity (Atuo et al. 2019; Hobart et al. 2019; Kramer et al. 2021b; Zulla et al. 2022; Wilkinson et al., in prep.). California spotted owl occupancy, colonization, adult survival, and reproductive success are all positively associated with the proportion of structurally complex forests (Franklin et al. 2000, p. 539; Blakesley et al. 2005, p. 1562; Tempel et al. 2014b, p. 2089; Tempel et al. 2016, p. 747). The biological and physical components that create habitat heterogeneity and complex structure are areas of multi-layered high canopy cover, large trees, coarse woody debris, understory and mid-story vegetation, patches of burned habitat, riparian habitat, large diameter standing dead trees (snags), and some open areas within a California spotted owl's home range.

Coarse woody debris (fallen dead trees and the remains of large branches on the ground) is an important habitat feature for California spotted owls because it provides food, shelter, and protection for California spotted owl prey species, especially woodrats (Waters and Zabel 1995, pp. 861-862; Pyare and Longland 2002, pp. 1016-1017; Innes et al. 2007, pp. 1523, 1526; Kelt et al. 2013, p. 1208). Coarse woody debris in areas of multi-layered high canopy cover is conducive for fungal growth, a food source for many California spotted owl prey species (Verner et al. 1992, pp. 71-72; Pyare and Longland 2002, pp. 1016-1017). Rates of prey capture by California spotted owls are observed to be higher in taller multilayered forests, in areas with higher vegetation heterogeneity, and near forest-chapparal edges (Wilkinson et al. in prep., p. 2). There are a variety of habitats within a heterogeneous landscape that California spotted owls use and which may provide specific resources. The size of a California spotted owl's home range increases as the heterogeneity, or number of different vegetation patches, increase (Williams et al. 2011, p. 333); the hypothesis is that there may be an optimal point of habitat heterogeneity for California spotted owls beyond which territory quality declines (Williams et al. 2011, p. 333).

Population Needs

Populations of California spotted owls must have adequate amounts of nesting, foraging, and roosting habitat containing the habitat components described above in sufficient amounts and the appropriate configuration on the landscape to support a stable or increasing growth rate. They also need connectivity between territories and home ranges. Populations meeting these requirements are better able to withstand stochastic events. In many instances, however, data are insufficient or completely lacking regarding a population's size and growth rate. In the absence of such data, we examine other characteristics that may serve as surrogate indicators of general population health and, subsequently, resiliency. Essentially, an assessment of the availability of a species' identified needs (suitable habitat, food, breeding sites) may allow us to make assumptions about the potential resiliency of any given population. However, unless there is a documented positive correlation between the availability of species' needs and a population's known demographic condition, the uncertainty regarding such assumptions must be made clear.

In the SSA report, we describe the demographic factors that are considered important for California spotted owls, including natal dispersal, survival, fecundity, occupancy, and population growth. We describe the importance of each demographic factor to California spotted owl persistence and how the individual needs influence these factors.

There is little available information about dispersal and dispersal habitat between the defined California spotted owl populations and analysis units within the SSA report and this proposed rule. Dispersal habitat is described for northern spotted owl as 50 percent of the forest matrix outside of activity centers in stands with an average of 28 cm (11 in) dbh and 40 percent canopy closure (Thomas et al. 1990, p. 15). This contrasts with dispersal for Mexican spotted owls, which may move across large areas of unforested habitat to access suitable habitat on different mountain ranges (Gutiérrez et al. 1995, p. 5; Gutiérrez et al. 2017, p. 242). It is unknown how far California spotted owls will disperse across unsuitable habitat to find a new territory, but adult northern spotted owls have been found to occasionally move long distances if forced out of a territory (Forsman in litt. 2018, p. 22).

For dispersal to be successful, many of the individual needs must be present within the areas to which California spotted owls disperse. Canopy cover, large trees, and coarse woody debris all must be available in sufficient amounts and the appropriate configuration on the landscape (habitat heterogeneity) for juveniles or sub-adults to successfully settle into a territory to begin breeding.

Survival for California spotted owls is closely linked to population growth and is important for maintaining population resiliency (Seamans and Gutiérrez 2007a, p. 57; Blakesley et al. 2010, p. 27). Adult California spotted owls have high annual survival rates ranging from 0.796-0.814 in different study areas within analysis units in southern California (LaHaye et al. 2004, p. 1056; Franklin et al. 2004, p. 22), and 0.811-0.891 in study areas within analysis units in the Sierra Nevada (Blakesley et al. 2001, p. 671; Franklin et al. 2004, p. 22; Blakesley et al. 2010, p. 10; Tempel et al. 2014a, p. 92). In comparison, juvenile survival is difficult to estimate due to dispersal, and has been found to be low, ranging from 0.087-0.333 in study areas within analysis units in the Sierra Nevada (Blakesley et al. 2001, p. 671; Tempel et al. 2014a, p. 92), and 0.368 for southern California (LaHaye et al. 2004, p. 1056). For northern spotted owl, juveniles tend to have high mortality during the dispersal phase (Miller 1989, pp. 41-44; Forsman et al. 2002, p. 18).

All the individual needs discussed above influence survival. For example, survival is related to the amount of forest dominated by medium to large trees, high canopy cover, and habitat complexity (Blakesley et al. 2005, p. 1554; Tempel et al. 2014b, pp. 2089, 2098; McGinn et al. 2022, p. 9). In northern spotted owls, habitat heterogeneity is correlated with higher survival rates (Franklin et al. 2000, p. 539).

Fecundity is defined as the ability to produce offspring and is measured by the number of viable female offspring

that an individual can produce over a specific time period. Annual reproductive output, measured by presence or absence of offspring in a nest, for female California spotted owls in a demographic study in the Sierra Nevada was found to range from 0.478-0.988 (Blakesley et al. 2010, p. 1). Reproduction throughout all the demographic studies has ranged from no reproduction within a study area to nearly all birds reproducing in a study area in a particular year (Franklin et al. 2004, pp. 32-33; Seamans and Gutiérrez 2007a, p. 65; Blakesley et al. 2010, p. 17; MacKenzie et al. 2012, p. 597; Tempel et al. 2014a, p. 91; Stoelting et al. 2015, p. 46). Fecundity, measured as female young produced per female annually, has been found to range from 0.284-0.409 in the Sierra Nevada and to be 0.362 in southern California (Franklin et al. 2004, pp. 11, 23).

Many of the individual needs discussed above influence fecundity. Reproductive output decreases as non-forest habitat increases within the area around the nest, and nest success increases as the presence of large remnant trees within the nest stand increases (Blakesley et al. 2005, p. 1554). Reproduction is positively correlated to the foliage volume above the nest tree (North et al. 2000, p. 797), although habitat heterogeneity is also important for reproduction (Franklin et al. 2000, p. 539; Tempel et al. 2014b, p. 2089; McGinn et al. 2022, p. 9) and foraging (Zulla et al. 2022, pp. 7-8). Annual variation in weather also plays a role in reproductive success (North et al. 2000, p. 797; Seamans and Gutiérrez 2007a, p. 57; MacKenzie et al. 2012, p. 597; Stoelting et al. 2015, p. 46). For example, California spotted owls experienced increased fecundity when a dry breeding season followed a previously wet year (LaHaye et al. 2004, pp. 1056, 1062). Although survival of breeding California spotted owls is an important factor that is closely connected to population growth, reproductive output may be more influential to population growth because it varies more than adult survival (Blakesley et al. 2001, p. 667; Seamans and Gutiérrez 2007a, p. 57).

In the SSA report and this proposed rule, we define California spotted owl occupancy as the stable (not transient) presence of at least one adult within a territory. California spotted owls select and defend territories in which they spend most of their life. California spotted owl pairs will only reproduce once they have established an occupied territory. The measure of occupancy has been found to be strongly correlated with regional abundance of California spotted owls and can provide reliable inferences on population trends (Tempel and Gutiérrez 2013, pp. 1093-1093).

Many of the individual needs discussed above need to be present in order for California spotted owls to occupy a territory. Occupancy is generally higher and more consistent with an increasing proportion of the territory containing large trees and high canopy cover (Blakesley et al. 2005, p. 1554; Seamans and Gutiérrez 2007b, p. 572; Roberts et al. 2011, p. 610; Tempel et al. 2014b, p. 2089; Gutiérrez et al. 2017, p. vxii). As the proportion of forest types that are not used for nesting (smaller, similar-aged young trees) increases, occupancy tends to decrease (Blakesley et al. 2005, pp. 1554, 1560).

In the SSA report and this proposed rule, we define California spotted owl population growth as the change in the number of individuals within a particular study area, which correspond to our analysis units. Population growth is determined by the demographic factors of survival, fecundity, and occupancy, with fecundity likely the most influential because it is more variable (Blakesley et al. 2001, p. 667; Seamans and Gutiérrez 2007a, p. 57; Seamans and Gutiérrez 2007b, p. 566; Blakesley et al. 2010, p. 27; Tempel and Gutiérrez 2013, pp. 1093-1094; Gutiérrez et al. 2017, p. 99). Population growth is variable throughout study areas in the Sierra Nevada DPS where we have available information, with documented declines ranging from −50 percent to −31 percent in some study areas and a population increase of 25 percent in another (Tempel et al. 2014a, pp. 86, 90-92; Conner et al. 2016, p. 15). The only available demographic data for the Coastal-Southern California DPS is from the San Bernardino National Forest. A population decline of −9 percent was observed from 1987-1998, with more recent occupancy analyses showing further declines in population size (LaHaye et al. 2004, pp. 1056, 1064; Tempel et al. 2022, p. 20, table 5). All individual needs described above need to be present for positive California spotted owl population growth.

Species Needs

At the species level, we assess the redundancy and representation of the entire California spotted owl's range to better understand the viability of the species. For the California spotted owl, we evaluate redundancy by considering the number of resilient populations distributed across the species' range. Having resilient populations distributed across the range increases the species' ability to withstand catastrophic events.

For this species, we evaluate representation by considering the distribution of populations across their various ecological settings and whether those populations are able to maintain adequate amounts of genetic diversity. Having a variety of ecological settings that the species can occupy and a breadth of genetic diversity increases the species' ability to withstand and adapt to long-term environmental changes.

Threats

Following are summary evaluations of eight threats analyzed in the SSA report for the California spotted owl: wildfire (Factor A), tree mortality (Factor A), drought (Factor A), climate change (Factor A), fuels reduction and forest management (Factor A), competition and hybridization with barred owls (
Strix varia
) (Factor E), rodenticides (Factor E), and development (Factor A). We also evaluate existing regulatory mechanisms (Factor D) and ongoing conservation measures.

In the SSA report, we also considered four additional threats: Overutilization due to recreational, educational, and scientific use (Factor B); disease (Factor C); predation (Factor C); and recreation (Factor E). We concluded that, as indicated by the best available scientific and commercial information, these threats are currently having little to no impact on the California spotted owl and thus the overall effect of these threats now and into the future is expected to be minimal. Therefore, we will not present summary analyses of those threats in this document, but we considered them in the current and future condition assessments in the SSA report, and we will consider them in our determination of the species' status. For full descriptions of all threats and how they impact the species, please see the SSA report (Service 2022, pp. 25-68).

For the purposes of this assessment, we consider the foreseeable future to be the amount of time on which we can reasonably determine a likely threat's anticipated trajectory and the anticipated response of the species to those threats. For this proposed rule, we consider the foreseeable future to be 40-50 years. This time period represents our best professional judgment of future conditions related to climate change for California, the California spotted owl's generation time, and the regeneration time of medium to large trees.

Wildfire

Fire is a natural part of California spotted owl habitat (Verner et al. 1992, pp. 247-248) and is necessary for maintaining heterogenous forests and

overall habitat heterogeneity. Wildfire and associated tree mortality can be beneficial or detrimental for the California spotted owl depending on scale and severity. Fires with predominantly low to moderate severity burn patterns, with small patches of high-severity fire scattered throughout the fire perimeter, can increase habitat heterogeneity, ultimately result in higher prey densities, increase amounts of forest edge for California spotted owl foraging, and provide for unburned refugia within the fire perimeter that have higher tree survival and more vegetative cover during the immediate postfire years (Roberts et al. 2011, p. 610; Lee et al. 2012, p. 792; Bond et al. 2013, pp. 114, 122; Eyes et al. 2017, p. 384; Blomdahl et al. 2019, pp. 1046, 1048, 1049). There is also evidence to suggest that more pyrodiverse (spatial or temporal variability in fire effects; Jones and Tingley 2021, p. 1) landscapes support greater habitat heterogeneity, which may promote greater biodiversity (Steel et al. 2021, pp. 7-8; Stephens et al. 2021, p. 5). For example, in areas where woodrats are the primary prey species, a juxtaposition of mature forests and open canopy patches promotes higher prey diversity and abundance, and northern spotted owls preferentially select for these areas (Zabel et al. 1995, p. 433; Ward and Noon 1998, p. 79; Franklin et al. 2000, p. 539; Zabel et al. 2003, p. 1027).

Although burned areas can reduce the amount of canopy cover available, California spotted owls forage on the edge of and within areas that have been burned at a range of severities (Bond et al. 2009, p. 1116; Bond et al. 2016, p. 1290; Eyes et al. 2017, p. 375) although typically avoiding larger areas of high-severity fire (Jones et al. 2016a, p. 304; Eyes et al. 2017, p. 383). Thus, many researchers advocate for the use of ecologically beneficial fire to help sustain California spotted owl habitat and report that low to moderate severity fire minimizes the effects of future high-severity wildfire (Stephens et al. 2019, pp. 395-396; Stephens et al. 2020, entire; Stephens et al. 2021, p. 5; Taylor et al. 2022, p. 4).

In contrast, large-scale, high-severity fires have a detrimental effect on both the California spotted owl and its habitat. Large-scale high-severity fire (often referred to as a megafire) is generally defined as over 10,000 ha (24,711 ac) of area burned with 75-100 percent canopy mortality (Jones et al. 2016a, p. 300; Linley et al. 2022, pp. 6, 8). Megafires can degrade or destroy California spotted owl habitat, completely incinerating large trees and canopy cover (Eyes 2014, p. ii; Roberts et al. 2015, pp. 112-115; Jones et al. 2016a, pp. 300-305). Habitat suitability for northern spotted owls decreased postfire and depended on fire severity (higher fire severity resulted in greater declines of habitat suitability) (Wan et al. 2020, p. 7); thus, megafires have a greater potential to alter the availability of suitable habitat.

The loss of habitat from large-scale, high-severity fires also results in direct impacts to California spotted owl individuals and populations. As megafires alter the number of large trees (including nest trees), multi-layered high canopy cover, habitat heterogeneity, and patch size, California spotted owl dispersal, fecundity, and occupancy are subsequently reduced. It has been observed that large patches of high-severity fire significantly reduce colonization (dispersal), occupancy, and habitat use across the California spotted owl's range (Eyes 2014, p. 42; Tempel et al. 2014b, p. 2089; Jones et al. 2016a, pp. 300, 303-305; Eyes et al. 2017, pp. 381, 384; Jones et al. 2019, p. 26; Jones et al. 2020, entire; Schofield et al. 2020, pp. 5-6; Jones et al. 2021a, p. 5; Tempel et al. 2022, p. 13) and for other subspecies (Rockweit et al. 2017, entire; Lesmeister et al. 2019, p. 13; Duchac et al. 2021, p. 12). Fires may cause direct mortality to eggs and juveniles during the nesting season, and fast-moving fires also have the potential to cause direct mortality to adult California spotted owl individuals (Jones et al. 2016a, p. 305). No data are available on how many California spotted owls are killed annually by direct impacts of large-scale, high-severity fire. Although most birds are able to move to escape direct morality from fires, smoke from fires can impact birds by damaging their lungs (Verstappen and Dorrestein 2005, p. 139). While many species have existed with frequent fire over evolutionary time, megafires and extreme smoke events are novel influences that may act as an additional selective pressure on certain species (Nimmo et al. 2021, p. 5689). There is limited research on the effects of wildfire smoke on wildlife in general, but there is clear evidence that smoke can have both acute and chronic health impacts on a variety of taxa, which may ultimately affect demographic rates (Sanderfoot et al. 2021, p. 13).

As discussed above, high-severity fire has negative effects on individual California spotted owls and their habitat, ranging from reduced occupancy to direct mortality of individuals. However, several publications conclude that spotted owls will continue to use areas burned at high-severity and, therefore, there are no negative effects of high-severity fire for California spotted owls (Lee and Bond 2015, entire; Hanson et al. 2018, entire; Hanson et al. 2021, entire; Lee 2018, entire). We have reviewed these publications and acknowledge this disagreement in the literature. However, our review of all the best available science, including those sources that conclude no negative effects, has led us to agree with the vast majority of science, which concludes that overall spotted owls avoid large patches of high-severity fire and that high-severity fire is increasing throughout California and the western United States. For more analysis on the conflicting results of these studies and our analysis, please see the SSA report (Service 2022, pp. 27-28).

Current conditions in the California spotted owl's range may contribute to ongoing fire risk, and depending on the portion of the range and the land manager, fire management activities may vary. Decades of fire suppression have led to overall higher canopy cover from small and medium trees, higher dead biomass density, and more surface fuels in forests of the western United States (Verner et al. 1992, pp. 247-248; Agee and Skinner 2005, p. 83). The historical fire return interval for the Sierra Nevada was around 11-16 years, but fire suppression over the last 100 years has led to a change in fire behavior of larger, more severe fires in recent years (Safford and Stevens 2017, pp. v-vi). The multi-layered high canopy cover and biomass provide important habitat for California spotted owls but also tend to increase the vulnerability of forests to high-severity fire (Verner et al. 1992, pp. 251-258; Agee and Skinner 2005, p. 83) in present day fire-suppressed forests. The higher fuel loads, particularly large, dead wood (like snags and logs), tend to burn at higher severity as densities increase (Lydersen et al. 2019, p. 7). In a recent megafire, dead biomass directly contributed to the fire effects observed, as areas with high amounts of dead biomass pre-fire burned at high severity (Stephens et al. 2022, p. 8).

On top of the higher fuel loads, extended droughts and longer wildfire seasons have led to larger and more severe fires in the California spotted owl's range and throughout western North America (Miller and Safford 2012, p. 41; Mallek et al. 2013, p. 1; Nigro and Molinari 2019, p. 20; Parks and Abatzoglou 2020, p. 4; Safford et al. 2022, p. 12). In 2020 and 2021, more than 1 million ha (2.4 million ac) burned in California, resulting in more area burned over these 2 years than in the past 7 years of all California fires

combined (Safford et al. 2022, p. 5). An increase in high-severity fire changes how fire interacts with important habitat features for California spotted owls. For example, fire often killed, but left standing, trees that would subsequently serve as locations for California spotted owl nests. However, large patches of high-severity fire burn hotter and can end up entirely consuming the features important to California spotted owls. Between the years of 2000 and 2014, 7 percent of suitable California spotted owl nesting habitat (a total of 85,046 ha (210,153 ac) out of 1,166,560 ha (2,882,633 ac)) was burned either partially at moderate severity (typically 25-50 percent tree basal area mortality) or entirely at high severity (typically >75 percent tree basal area mortality), causing ≥50 percent tree basal area mortality and reducing canopy cover to <25 percent (Stephens et al. 2016, pp. 1, 9).

The size and severity of a fire determines how much it will impact California spotted owls at the population level. If a high-severity fire occurs in a large enough area, it can eliminate entire territories or home ranges of California spotted owls, displacing individuals that may or may not establish a new territory (Jones et al. 2016a, pp. 300-305). Site occupancy by California spotted owls after wildfire appears to be a function of the amount of suitable habitat remaining after the fire (Gutiérrez et al. 2017, p. xxiii). If habitat becomes unsuitable, it takes decades for large trees to reestablish on the landscape. Based on fire activity and anticipated trends over the next 75 years, the cumulative amount of nesting habitat burned at ≥50 percent tree basal area mortality will exceed the total existing habitat in the Sierra Nevada (Stephens et al. 2016, pp. 1, 12). In other words, the loss of suitable California spotted owl habitat would exceed the rate of new forest growing post-fire (Stephens et al. 2016, pp. 11-13). Thus, future habitat persistence for California spotted owls is concerning given that high-severity fire appears to be increasing across all lands (both public and private) occupied by California spotted owls and throughout the western United States (Parks and Abatzoglou 2020, pp. 4-5). When private lands are considered separately, the odds of high severity fire occurring on industrially managed forests and adjacent lands were 1.8 and 1.4 times higher, raising some concern over California spotted owl persistence on private lands (Levine et al. 2022, p. 4).

In the Sierra Nevada, the proportion of high severity fire throughout the California spotted owl's range has dramatically increased in recent years. The proportion of high-severity fire in California montane forests in 2020 was on average 43-76 percent higher than the combined average between 1984 and 2008, and was three to six times higher than the estimates of pre-Euroamerican settlement (Safford et al. 2022, p. 17). Between 1984-2019, 1,084,171 ha (2,679,044 ac; 55.7 percent) burned throughout the California spotted owl range in the Sierra Nevada with 317,605 ha (784,820 ac; 46.6 percent) burned at high severity (Keane in litt. 2022, p. 3). In contrast, between 2020 and 2021, 862,625 ha (2,131,593 ac; 44.3 percent) burned throughout the California spotted owl's range with almost 363,812 ha (899,000 ac; 53.4 percent) of that at high severity (Keane in litt. 2022, p. 3). This comparison illustrates how megafires in 2020 and 2021 burned more habitat at high severity in 2 years than fires over the past three and a half decades. In addition, between 1984 and 2021, 50 percent of California spotted owl PAC acres have been impacted by wildfire, with 56 percent of that total burned in 2020 and 2021. Further, of the 56 percent that burned between 2020 and 2021, 65 percent burned at high severity (Keane in litt. 2022, p. 5). Because California spotted owls are displaced from areas where the entire PAC or majority of the PAC has burned at high severity, it is unlikely the species will continue to persist in these areas until the habitat can recover, which can take decades.

We conducted a fire severity analysis within the entire California spotted owl's range; details of the methodology used in this analysis are available in the SSA report (Service 2022, pp. 29-30). Of the California spotted owl's range, approximately 47 percent burned between 1984 and 2021, with 15 percent at high severity. Most of the area burned at high severity occurred in 2020 and 2021, with 2 percent and 4 percent, respectively (Service 2022, table 3). Additionally, based on an existing dataset from the California Department of Forestry and Fire Protection of the potential threat of future wildfire in California, the majority of the California spotted owl's range occurs within the very high wildfire threat category (Service 2022, figure 8). Much of the coastal-southern California population of the California spotted owl falls within the extreme fire risk. This dataset contains fire information through 2014, and so does not consider how the recent fires from 2014 to 2021 affect future fire threat. Overall, we expect that the pattern of both area burned and wildfire severity will continue or increase into the future due to the effects of climate change.

Some regulatory mechanisms and conservation measures can reduce the potential severity or scale of wildfires. Wildfire fuel reduction treatments, such as prescribed fire and mechanical thinning, can reduce the amount or degree of spotted owl habitat loss from a high-severity fire, and a balanced approach to fuel reduction treatments may ensure suitable California spotted owl habitat is maintained (Jones et al. 2016a, p. 305; Service 2017, pp. 24-25; Chiono et al. 2017, p. 1; Jones et al. 2021a, entire). The 2004 USFS Sierra Nevada Forest Plan Amendment has a goal of actively restoring fire-adapted ecosystems by reducing unnaturally dense conditions, and there are also measures in place in the framework to avoid disturbance within California spotted owl PACs to the greatest extent possible (USFS 2004, pp. 34-35). Fuel reduction treatments are actively taking place on USFS land, but special considerations, including the timing of treatments to avoid the breeding season and the methods that are used, are evaluated to avoid impacts to owls within PACs. In 2017 and in 2020, an MOU was signed by Sierra Pacific Industries, California Department of Forestry and Fire Protection, National Fish and Wildlife Foundation, and the USFS to coordinate on certain actions that may contribute to forest fuel reductions and California spotted owl conservation. The purpose of the MOU is to try to minimize the threat of large-scale, high-severity fire while still providing quality habitat for California spotted owls. However, large-scale, high-severity fire cannot be completely addressed by regulatory mechanisms. Fuel reduction treatments may not prevent catastrophic damage in an extreme fire event; however, when fire is a part of the fuel reduction treatment, future fire severity can be reduced and more fire treatments should be included to achieve fuels reduction goals, including areas surrounding spotted owl nests and riparian corridors (North et al. 2021, pp. 527, 529; Taylor et al. 2022, p. 4).

High-severity fire is likely to continue to be a threat into the future for California spotted owls. Although some individuals could be harmed or killed by large fires, the primary impact of this threat is habitat-based. These habitat changes also affect demographic parameters: following high severity fires, colonization declines and territory extinction increases, leading to overall declines in occupancy (Tempel et al. 2022, pp. 13-16). Overall, large-scale, high-severity fire is currently and will

likely continue to be a threat throughout the range of the California spotted owl, including for both the Sierra Nevada and the coastal-southern California populations.

Tree Mortality

Widespread increases in tree mortality have been occurring in California due to drought, disease, and bark beetles above historical levels of mortality (van Mantgem et al. 2009, pp. 521-523; Asner et al. 2015, p. 249; McIntyre et al. 2015, p. 1458; Preisler et al. 2017, p. 166). When tree stand densities are too high compared to available resources (water, light, nutrients), trees become stressed due to competition for resources and thus are more vulnerable to mortality (USFS 2017, p. 9). Large trees are often especially prone to drought, disease, and beetle-related mortality (Smith et al. 2005, p. 266; Mueller et al. 2005, p. 1085; Allen et al. 2010, p. 668; McIntyre et al. 2015, p. 1458). Increased tree mortality may be contributing to loss of California spotted owl habitat (Gutiérrez et al. 2017, p. 137), but the magnitude of the impacts on California spotted owls is uncertain. Large-scale tree mortality reduces the availability of canopy cover and large trees, potentially resulting in California spotted owl population declines because of reduced habitat available for dispersal and occupancy. However, some tree mortality events can have some positive effects on California spotted owl habitat, as these events contribute to habitat heterogeneity and the availability of coarse woody debris for prey species.

Between 2010 and 2016, an estimated 102 million trees died across about 3,106,367 ha (7,676,000 ac) throughout California (Tree Mortality Task Force 2017, p. 2). By February 2019, total tree mortality in California increased to an estimated 147 million dead trees (Cal Fire and USFS 2019, p. 1). The latest estimate shows that between 2010 and 2021, the drought combined with subsequent beetle attacks resulted in approximately 173 million dead trees in California with approximately 3.3 percent of the surveyed forest area in 2021 showing signs of elevated mortality (USFS 2021, p. 5). The tree mortality events are particularly severe in the southern Sierra Nevada area. Most of the tree mortality observed is due to effects from the 2012-2016 drought, with less mortality occurring from 2018-2021; however, another drought period started in 2020 (USFS 2021, p. 5).

In 2015, the Governor of California declared a state of emergency due to the unprecedented number of dead and dying trees in the State. In response, the California Tree Mortality Task Force, which is now the Forest Mortality Working Group within the California Wildfire and Forest Resilience Task Force, was created to coordinate emergency protective actions and monitor ongoing conditions. The group collects and manages the tree mortality data, provides recommendations to land managers, presents grants for research funding, and provides public outreach. The task force will likely continue to provide the services listed into the future due to the ongoing and large-scale nature of the tree mortality events in California.

Regulatory mechanisms and management actions could provide some protection from the effects of tree mortality. Efforts to restore historical forest conditions and reduce stand densities through fuels reduction treatments (mechanical thinning, prescribed fire, etc.) may indirectly contribute to reducing future tree mortality by reducing competition. Further, the goal should be to eliminate the excessive levels of tree mortality currently being observed in the landscape and not limit all tree mortality, as tree mortality is a natural part of the forest ecosystem and ultimately creates features important to California spotted owls (snags, tree cavities). Tree mortality is likely to continue throughout the range of the California spotted owl due to predicted increases in drought conditions that will likely continue to weaken trees and make them susceptible to bark beetles and disease (Millar and Stephenson 2015, pp. 823-826; Young et al. 2017, pp. 78, 85). Excessive tree mortality is likely to continue to be a threat into the future for the California spotted owl.

Drought

California has experienced extreme drought conditions in 2007-2009 and 2012-2016 (Williams et al. 2015, pp. 6823-6824; CDWR 2021, p. 4), and as of May 2022, a majority of the California spotted owl's range is considered in severe to moderate drought (CDWR 2022, entire). Anthropogenic warming likely contributed to more recent drought anomalies and increases the overall likelihood of extreme droughts in California into the future (Williams et al. 2015, pp. 6819, 6826; CDWR 2022, entire).

Drought conditions can negatively impact the California spotted owl's ecological needs. As described above, drought conditions contribute to tree mortality, which reduces canopy cover, likely leading to a decline in occupancy. Further, drought conditions likely reduce the availability of prey species (Franklin et al. 2000, p. 589; Glenn et al. 2010, p. 2549; Glenn et al. 2011, p. 174). Drought and hot temperatures in the previous summer are linked to lower reproductive success in California spotted owls (LaHaye et al. 2004, p. 1066) and lower survival and recruitment in northern spotted owls in the next breeding season (Glenn et al. 2011, pp. 159, 174). Inversely, increases in precipitation either before or after the nesting season are linked to increased survival and fecundity in all three subspecies of spotted owls (Seamans et al. 2002, p. 321; LaHaye et al. 2004, pp. 1056, 1064; Glenn et al. 2011, pp. 159, 174). Thus, drought likely negatively impacts the California spotted owl's habitat components, and its demographic needs of dispersal, survival, fecundity, and occupancy. No regulatory mechanisms or conservation measures in place ameliorate the direct impacts of drought. It is likely that drought conditions will continue to be a threat into the future across the California spotted owl's range and will likely worsen due to the effects of climate change.

Climate Change

Scientific measurements spanning several decades demonstrate that changes in climate are occurring and that the rate of change has been faster since the 1950s. There is strong scientific support for projections that warming will continue through the 21st century, and that the magnitude and rate of change will be influenced substantially by the extent of greenhouse gas emissions (Meehl et al. 2007, pp. 760-764, 797-811; Ganguly et al. 2009, pp. 15555-15558; Prinn et al. 2011, pp. 527, 529; IPCC 2013, pp. 19-23).

Projected changes in climate and related impacts can vary substantially across and within different regions of the world (IPCC 2013, pp. 15-16). Therefore, we used downscaled projections from California's Fourth Climate Change Assessment, including the following four regional assessments that cover the California spotted owl's range: Sierra Nevada (Dettinger et al. 2018, entire), the Central Coast Region (Langridge 2018, entire), Los Angeles (Hall et al. 2018, entire), and San Diego (Kalansky et al. 2018, entire). Ten global climate models were used for all four regional assessments, and each model considered two different emissions scenarios, one in which greenhouse gas emissions continue to increase into the next century (RCP 8.5) and one in which greenhouse gas emissions stabilize by mid-century and then decline to levels

seen in the 1990s by the end of the century (RCP 4.5) (Dettinger et al. 2018, pp. 15, 17; Hall et al. 2018, p. 9; Kalansky et al. 2018, p. 18; Langridge 2018, p. 12).

Under both emissions scenarios, projected annual average temperatures throughout the California spotted owl's range are projected to increase. The largest increases under both emissions scenarios and timeframes are projected for the eastern portions of the Sierra Nevada (Dettinger et al. 2018, p. 17, figure 2.3). Projected changes will result in greater temperatures than historically experienced in the Sierra Nevada, and this degree of temperature change will likely result in a shift in the rain to snow transition by 1,500-3,000 feet (Dettinger et al. 2018, pp. 17, 20). Projected temperature increases are more pronounced in the inland portions of the Central Coast Region, with the ocean acting as a buffer for coastal areas (Langridge 2018, p. 14, figure 4). In addition, the average number of extremely hot days (defined as days that exceed the 98th percentile of observed, historical (1961-1990) daily maximum temperatures between April 1 and October 31) are expected to increase throughout the Central Coast Region (Langridge 2018, pp. 14-15, table 4).

Regional assessments covering southern California include the Los Angeles and San Diego Regional Assessments (Hall et al. 2018, entire; Kalansky et al. 2018, entire). Projected annual average maximum temperatures throughout the Los Angeles Region increase under both emissions scenarios (Hall et al. 2018, p. 10, figure 2). For the San Diego Region, projected annual average maximum and minimum temperatures also increase under both emissions scenarios. Similar to the Central Coast Region, these changes will be more pronounced in the interior portions of the Los Angeles and San Diego Regions (Hall et al. 2018, p. 11, figure 3).

In addition to temperature projections, the regional assessments for California's Fourth Climate Change Assessment also considered future changes in precipitation, both the amount and the timing. Within the Sierra Nevada Region, changes in precipitation are projected to be relatively small and will vary depending on the area. In general, average annual precipitation in the southern portion of the Sierra Nevada Region is projected to stay similar or decrease by 5 percent, regardless of emission scenario. In other portions of the Sierra Nevada Region, particularly along the eastern side, the amount of precipitation is projected to increase by up to 10 percent. In addition to projections showing the northern portions of the range will receive more precipitation than southern portions, areas at higher elevations are also more likely to receive an increase in precipitation. Although the average change in precipitation is projected to be small, the models show there will be an increase in extreme conditions with more dry days overall interspersed with higher intensity precipitation events, when they do occur (Dettinger et al. 2018, p. 19). Further, in some areas more precipitation will fall as rain instead of snow, as the rain to snow transition is projected to shift by 457-914 m (1,500-3,000 ft) (Dettinger et al. 2018, pp. 17, 20).

Similar to the Sierra Nevada Region, interannual variability within the Central Coast Region is expected to increase with more dry days overall, but more precipitation when rain events do occur (Langridge 2018, p. 16). In southern California, the amount of precipitation in the Los Angeles and San Diego Regions is highly variable (Hall et al. 2018, p. 12, figure 5; Kalansky et al. 2018, p. 24). Similar to other regions, projections for the Los Angeles and San Diego Regions show an increase in extreme conditions such as high-intensity precipitation events, known as atmospheric rivers, and severe drought conditions (Hall et al. 2018, pp. 13-14, figure 6; Kalansky et al. 2018, pp. 24-25, figures 7 and 9).

Because the California spotted owl has a wide geographic range and the projected changes in climate vary across the range, the effects those changes will have on the species and its habitat will vary. Future climate projections of Sierra Nevada vegetation distribution indicate that low- and mid-elevation forests are vulnerable to conversion to unsuitable habitat for California spotted owls, such as shrublands and grasslands (Gutiérrez et al. 2017, p. 215). These changes in climate may also include potential shifts in forest communities upslope, which would have impacts on both the California spotted owl's habitat and prey habitat (Gutiérrez et al. 2017, pp. 132, 215, 288). This potential upslope shift in suitable habitat may mitigate some climate-induced habitat threats over ecological time, although it would require many decades for suitable large nest trees to develop in areas where they do not currently exist (Gutiérrez et al. 2017, p. 215). These differences in net habitat loss versus net habitat gained under future climate scenarios will likely depend not only on the rate of warming but also how individual plant and prey species respond (Seamans and Gutiérrez 2007a, p. 61).

Changing climatic conditions may have direct impacts on California spotted owl physiology, survival, reproduction, recruitment, or population growth. The thermal neutral zone (the range of temperatures tolerated by a warm-blooded animal) for California spotted owls is 18.2-35.2 °C (64.8-95.4 °F) (Weathers et al. 2001, p. 682). Above this zone, California spotted owls experience heat stress (Weathers et al. 2001, p. 678). The relatively low thermal neutral zone may make California spotted owls more susceptible to increased temperatures or cause behavioral or habitat shifts to cooler microclimates on the landscape. Behaviorally, California spotted owls can select cooler microclimates for roosting, especially within warmer forest stands (McGinn et al. in review, p. 2). Changing climatic conditions may also have indirect impacts including changes in habitat and prey distribution, abundance, and quality. California spotted owls must be able to adjust to the changing climate through behavioral changes, spatial shifts, or adaptation in order to persist. Under projected warming conditions in the future, cooler microclimate refugia are likely to be critically important for the persistence of California spotted owl individuals and populations (McGinn et al. in review, p. 3). It is likely that climate change will reduce the quantity and quality of California spotted owl habitat, which would likely result in population impacts, including a decrease in dispersal, fecundity, and occupancy. Both the habitat components and demographic factors of California spotted owls will likely be impacted by climate change, but the full extent of impacts climate change may have on California spotted owls is poorly understood (Wan et al. 2018, p. 690).

Climate modeling specific to the central Sierra Nevada portion of the California spotted owl's range has shown that maintaining high canopy cover, especially at higher elevations, will be important for California spotted owls to persist into the future, as high canopy cover helps maintain future refugia for individuals to select for cooler microclimates (Jones et al. 2016b, entire). Under both a low climate change prediction scenario (RCP 2.6) and a high climate change scenario (RCP 8.5), California spotted owl occupancy decreases in comparison to baseline climate conditions (Jones et al. 2016b, p. 901). However, this model did not consider projected increases in frequency and size of high-severity fires due to climate change, which would likely result in more significant declines

in occupancy than predicted by the model (Jones et al. 2016b, p. 903). Earlier modeling of spotted owl response to projected climate changes show that different subspecies and populations of spotted owls are anticipated to respond differently across their ranges (Peery et al. 2011, p. 14).

The climate change projections described above suggest increasing interannual climate variability throughout the range of the California spotted owl. Interannual climate variability is defined as when annual weather patterns differ from historical average climate, including prolonged drought conditions, heavy rain conditions, and higher or lower than average temperatures. Interannual climate variability has been shown to have impacts on the survival and reproductive success of California spotted owls. Drought conditions and hot temperatures during the summer have been found to reduce fecundity in California spotted owls during the next breeding season (LaHaye et al. 2004, p. 1056). Increases in precipitation either before or after the nesting season are linked to increased survival and fecundity, whereas increased precipitation during the nesting season reduces reproductive success (North et al. 2000, p. 804; LaHaye et al. 2004, pp. 1056, 1064). It is hypothesized that northern spotted owls exhibit a bet-hedging reproduction strategy and that an absence of reproduction is linked to environmental conditions (Franklin et al. 2000, pp. 539, 576). California spotted owls likely have a similar bet-hedging reproductive strategy (Stoelting et al. 2015, p. 46; Gutiérrez et al. 2017, pp. 14-15). California spotted owls are sensitive to warm temperatures and, therefore, may be physiologically sensitive to weather patterns with increased temperatures (Weathers et al. 2001, p. 684). Temperature, either too hot or too cold, may affect spotted owls directly by increasing energy demands (Gutiérrez et al. 2017, p. 20). This increase may have direct impacts on the physiology of spotted owls or on breeding if mates must bring more food to the nest for the female to survive. Increased interannual climate variability due to climate change will likely impact the California spotted owl throughout its range, which would result in lower fecundity.

Regulatory mechanisms and management actions that are or could potentially provide some protection from the effects of climate change include the Clean Air Act (42 U.S.C. 7401
et seq.
) and the California Global Warming Solutions Act. Both address climate change by reducing greenhouse gas emissions within the United States and California, respectively. There are no regulatory mechanisms or management actions that fully address the effects of the climate change.

The effects of climate change will continue to impact California spotted owls into the future by exacerbating the negative influencing factors described above, especially extreme weather events such as prolonged drought and severe storms. The loss or reduction of suitable habitat throughout the California spotted owl's range will likely reduce the subspecies' reproduction, occupancy, survival, recruitment, and population growth.

Fuels Reduction and Forest Management

Forest management has long been a controversial topic regarding species that require old growth forest habitat, including the spotted owl (Gutiérrez 2020, p. 337). With the increasing frequency and extent of high-severity fire in California in recent decades, fire mitigation has become a key issue for spotted owl management and conservation. The goal of fuels management is to reduce the buildup of fuels in forests that contribute to these large-scale, high-severity fires, which can effectively mitigate subsequent fire behavior and their effects, even under extreme weather (Hessburg et al. 2021, p. 7; Prichard et al. 2021, p. 9). The long-term benefits of properly managed fuel treatments for reducing the risk of severe wildfire are likely to outweigh the short-term negative impacts to spotted owl habitat (Ager et al. 2007, pp. 54-55; Roloff et al. 2012, p. 7; Jones et al. 2021b, pp. 4-5). These trade-offs are complex and ultimately depend on the extent that treatments have negative impacts to owl habitat and the magnitude of effects from subsequent wildfires (Jones et al. 2021b, p. 2). Fuels reductions and forest management practices vary throughout the California spotted owl's range. Below, we discuss clearcutting, mechanical thinning, salvage logging, and prescribed fire, and the positive and negative influences that these practices can have on the species.

Clearcutting, sometimes referred to as even-aged management, is defined as an even-age regeneration or harvest method that removes all trees in the stand, producing a fully exposed microclimate for the development of a new age class in one entry (Gutiérrez et al. 2017, p. 292). The natural range of variation for forest gaps in the Sierra Nevada has been found to range from 0.03-1.17 ha (0.07-2.89 ac) (Safford and Stevens 2017, p. 140), and within the SSA report and this proposed rule, clearcutting refers to complete removal greater than the natural range of variation.

Clearcutting is a mostly historical threat to California spotted owls, although it still occurs in some areas of the Sierra Nevada. By removing entire stands of trees, clearcutting reduces the amount of large trees, high canopy cover, and coarse woody debris available for California spotted owls. Commercial timber harvest no longer occurs within the California spotted owl's range on public lands in the Coastal-Southern California DPS (Gutiérrez et al. 2017, p. 254). Clearcutting also does not occur on USFS lands on the eastern side of the Sierra Nevada range (Boatner in litt. 2022). Clearcutting still occurs on private timber harvest lands but is limited to 8.1-ha (20-ac) parcels by California State forest practice rules (California Code of Regulations (CCR), title 14, article 3 (14 CCR 913
et seq.
)). Additionally, there must be at least 91.44 m (300 ft) of forested area between clearcuts, and adjacent lands cannot be cut for at least 5 years (14 CCR 913
et seq.
). Even with the reduction of clearcutting in recent history, it will take decades or centuries for large trees to grow back from the past removal practices; therefore, there are residual effects that may be impacting California spotted owl populations and the habitat that is available (Jones et al. 2018, p. 1). California spotted owls may use clearcut habitat, likely for foraging activities, but these areas are used significantly less than high canopy cover and large tree areas (Atuo et al. 2019, pp. 295, 301-302).

Mechanical thinning is a forest management strategy to thin trees either in even or uneven-aged stands by removing trees in rows, strips, or by using fixed pacing intervals, usually implemented to meet forest management objectives. It can be done for commercial harvest of trees or to reduce fuel loads to decrease the likelihood of large-scale, high-severity fires (Gutiérrez et al. 2017, p. 292). Within the SSA report and this proposed rule, we use “mechanical thinning” to include both individual tree selection (new age classes are created in uneven-aged stands by removing individual trees of all size classes more or less uniformly throughout the stand to achieve desired stand structure) and group tree selection (treatment involves salvage harvest in a stand where small groups of trees are harvested because of tree mortality due to windstorm, wildfire, insects, disease, or other animals).

Mechanical thinning is actively used to manage forests occupied by California

spotted owls and can have positive or negative impacts on the California s

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2023-03526. Public record. Not legal advice.