Endangered and Threatened Wildlife and Plants; Notice of Determination To Retain the Threatened Status for the Coastal California Gnatcatcher Under the Endangered Species Act

DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

Endangered and Threatened Wildlife and Plants; Notice of

Determination To Retain the Threatened Status for the Coastal

California Gnatcatcher Under the Endangered Species Act

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of determination.

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SUMMARY: The Fish and Wildlife Service (Service), announces a

determination affirming its earlier conclusion (March 30, 1993; 58 FR

16742) that the coastal California gnatcatcher (Polioptila californica

californica), a small, insectivorous songbird, is a distinct subspecies

and, thus, meets the definition of a ``species'' pursuant to the

Endangered Species Act of 1973, as amended (Act). In addition, the

Service affirms its earlier conclusion (58 FR 16742) that the southern

limit of this subspecies extends to about 30 deg. north latitude near

the vicinity of El Rosario, Baja California, Mexico. Based on these

determinations, the Service concludes that its March 30, 1993, decision

that the coastal California gnatcatcher is a threatened species was

correct. Federal protection for the coastal California gnatcatcher is

thus continued.

EFFECTIVE DATE: March 23, 1995.

ADDRESSES: The complete administrative records and files for this

determination and all related rule promulgations and notices are

available for inspection, by appointment, during normal business hours

at the Fish and Wildlife Service Carlsbad Field Office, 2730 Loker

Avenue West, Carlsbad, California 92008.

FOR FURTHER INFORMATION CONTACT: Mr. Gail C. Kobetich, Field

Supervisor, at the above address (telephone 619/431-9440).

SUPPLEMENTARY INFORMATION:

Background

The coastal California gnatcatcher (Polioptila californica

californica), a subspecies of the California gnatcatcher, is a small,

long-tailed member of the thrush family Muscicapidae. The subspecies is

restricted to California and Baja California, Mexico, and is an

obligate resident of coastal sage scrub, which is one of the most

depleted habitat types in the United States (58 FR 16742). The plumage

color of the species is dark blue-gray above and grayish-white below.

The tail is mostly black above and below. This subspecies is

distinguished from the other subspecies by its darker body plumage,

less extensive white on tail feathers (rectrices 5 and 6), and longer

tail (Atwood 1991). The male has a distinctive black cap that is absent

during the winter. Both sexes have a distinctive white eye-ring.

Vocalizations of this species include a call consisting of a rising and

falling series of three kitten-like mew notes (National Geographic

Society 1983).

The California gnatcatcher was originally described as a distinct

species (Polioptila californica) by Brewster (1881) based on specimens

collected by Stephens in 1878. Later taxonomic treatments (e.g., Coues

1903 and Chapman 1903) reflected Brewster's (1881) conclusions.

Grinnell (1926), however, later concluded that the species was a form

of the black-tailed gnatcatcher (Polioptila melanura), which inhabits

the Sonoran and Chihuahuan Deserts of the southwestern United States

and northwestern Mexico. Subsequent scientific publications (American

Ornithologists' Union 1931, Grinnell and Miller 1944, Friedmann 1957,

American Ornithologists' Union 1957) adhered to the species limits as

defined by Grinnell (1926). Three subspecies of the black-tailed

gnatcatcher were recognized for southwestern California and western

Baja California, Mexico: P. m. californica (ranging from Los Angeles

County, California (formerly northward to Ventura County), south to

about 30 deg. north latitude in Baja California, Mexico), P. m.

pontilis (resident in central Baja California), and P. m. margaritae

(ranging from about 27 deg. north latitude south to the Cape region of

Baja California) (American Ornithologists' Union 1957).

Based on identified differences in ecology and behavior that were

elucidated as a result of specimen study and statistical analysis,

Atwood (1988) proposed that Polioptila californica was specifically

distinct from P. melanura. This finding was subsequently formally

adopted by the American Ornithologists' Union Committee on

Classification and Nomenclature (American Ornithologists' Union 1989),

thus affirming Brewster's (1881) original taxonomic placement with

respect to species. The American Ornithologists' Union 1989 publication

did not address subspecies other than to refer the reader to the

American Ornithologists' Union 1957 checklist of North American birds.

The coastal California gnatcatcher, Polioptila californica

(=melanura) californica, has been recognized as a distinct race or

subspecies since Grinnell's (1926) publication (e.g., American

Ornithologists' Union 1931, Grinnell and Miller 1944, Friedmann 1957,

American Ornithologists' Union 1957, Garrett and Dunn 1981, Unitt 1984,

Phillips 1991, Atwood 1991). As indicated above, this subspecies occurs

from Los Angeles County (and, formerly, Ventura County) south to about

30 deg. north latitude in Baja California, Mexico. Although Atwood

(1988) proposed merging P. californica californica with a more

southerly subspecies of P. californica, he later (1991) retracted this

conclusion.

On March 30, 1993, the Service published a final rule determining

the coastal California gnatcatcher (Polioptila californica californica)

to be a threatened species (58 FR 16741). In making this determination,

the Service relied, in part, on taxonomic studies conducted by Dr.

Jonathan Atwood of the Manomet Bird Observatory. As is standard

practice in the scientific community, the Service did not request, nor

was it offered, the data collected and utilized by Atwood in reaching

his conclusions. Instead, the Service cited the conclusions presented

by Atwood in a peer reviewed, published scientific article pertaining

to the subspecific taxonomy of the California gnatcatcher (Atwood

1991).

The Endangered Species Committee of the Building Industry

Association of Southern California and other plaintiffs subsequently

filed a suit challenging the listing on several grounds. In a

Memorandum Opinion and Order filed in the United States District Court

for the District of Columbia on May 2, 1994, the Court vacated the

listing determination, holding that the [[Page 15694]] Secretary of

Interior (Secretary) should have made available the underlying data

that formed the basis of the Atwood (1988) report in light of the

controversy surrounding inconsistent conclusions reached by Atwood in

his 1988 and 1991 studies.

Following the Court's decision, Atwood released his data to the

Service. These data were, in turn, made available to the public for

review and comment on June 2, 1994 (59 FR 28508). By order of June 16,

1994, the Court reinstated threatened status for the coastal California

gnatcatcher pending a determination by the Secretary whether the

listing should be revised or revoked in light of his review of the

subject data and public comments received during public comment

periods. This notice constitutes the Service's determination in

response to the Court's June 16, 1994, order.

Summary of Comments and Recommendations

A proposed rule to list the gnatcatcher as endangered was published

on September 17, 1991 (56 FR 47053). Public comments were solicited and

two public hearings were held on the proposed rule. Notification of the

hearings was published in the Federal Register on February 7, 1992 (57

FR 4747). A legal notice announcing the hearings and inviting general

public comment on the proposal was also published on February 7, 1992

in the Los Angeles Daily News, Los Angeles Times, Riverside Press-

Enterprise, and the San Diego Union-Tribune. Public hearings were

conducted in Anaheim, California, on February 25, 1992, and in San

Diego, California, on February 27, 1992. A notice of extension and

reopening of the comment period for 30 days to obtain additional

information on gnatcatcher taxonomy was published on September 22, 1992

(57 FR 43688). On February 11, 1993, the Service published a notice

announcing the reopening of the public comment period on the proposed

rule for 20 days and the availability of a report prepared by Service

taxonomists on the taxonomic validity of P. c. californica (58 FR

8032). On March 30, 1993, the Service published a final rule

determining the coastal California gnatcatcher to be a threatened

species (58 FR 16741). That same day, a proposed special rule pursuant

to section 4(d) of the Act was published (58 FR 16758). The final

special rule was published on December 10, 1993 (58 FR 65088).

Following the Court's Order of May 2, 1994, and receipt of Atwood's

data, the Service announced the availability of these data and the

opening of a public comment period on June 2, 1994 (58 FR 28508).

Atwood's data were sent to 15 parties upon request. With the approval

of the Court, the public comment period was extended to December 1,

1994 (59 FR 53628), to allow the public additional time to receive and

then comment upon the raw data and methodology utilized by Atwood.

During this 6-month public comment period, Dr. William Link and Mr.

Grey Pendleton of the National Biological Service, Department of the

Interior (Department), conducted a new and independent analysis of

Atwood's data (Link and Pendleton in litt. 1994). To assure that the

Service utilizes the best scientific information available in the

implementing the Act, it is policy (59 FR 34270) to seek independent

review of the scientific basis for listing and recovery actions.

Consistent with this policy, the Service solicited comments on the

National Biological Service document and all other public comments

received by December 1, 1994, from the general public, including

scientists with an expertise in avian taxonomy. A new 30-day public

comment period (59 FR 66509) was opened on December 27, 1994, to allow

the public to review and comment on these documents. This final comment

period closed on January 26, 1995.

A total of 31 comments pertaining to either (1) Atwood's data,

methodology, or results, or (2) the taxonomy of the gnatcatcher was

received during the final two comment periods. This total includes 21

comments received prior to December 1, 1994, and an additional 10

comments received during the final comment period. Included among the

comments were three new, independent analyses of Atwood's data. After a

review and consideration of all such comments, five relevant issues

have been identified and are discussed below. The five issues encompass

all substantive comments pertaining specifically to Atwood's data,

analyses, and conclusions regarding the taxonomy and geographic range

of the coastal California gnatcatcher.

Issue 1: Several commenters noted that Atwood's apparent discarding

of raw data precludes an appropriate analysis of his conclusions. One

commenter in particular was disturbed that ``Atwood no longer has the

raw data used in his original analyses.'' Another commenter noted that

Atwood admitted to discarding computer programs used in the analysis of

the data subsequently analyzed and reported in his 1991 publication.

Some stated that differences existed between the data sets used in

Atwood (1988), Atwood (1991) and that provided to the Service and the

public (Atwood in litt. 1994a).

Service Response: Atwood (in litt. 1994b) has stated that the

measurements provided to the general public following the May 2, 1994,

Court Order ``represent the total and unmodified data set that formed

the basis for my 1988 and 1991 publications on gnatcatcher

morphology.'' Atwood (in litt. 1994b) also indicated that only one

difference existed between the computer file data set transmitted to

the public and the data on the original paper forms that he discarded

after entering the data into a computer file, the sex of a single

specimen from sample area SI29 was corrected. Atwood (in litt. 1994b)

further indicated that he verified (in 1985) the data on the computer

by comparing it with the hand-written information on the paper forms.

The Service concludes that there is no reason to doubt the veracity of

Atwood in this regard.

Because data on paper forms cannot readily be subjected to

statistical analysis, the data transferred to a computer or computer

disk are, in essence, the raw data at issue. The Service, therefore,

rejects the contention that Atwood discarded his raw data, thereby

precluding reanalysis of the data.

After providing his data, Atwood realized that discrepancies in

sample size existed between data reported in his dissertation, his

monograph (Atwood 1988), his subspecies paper (Atwood 1991), and data

provided to the Service. He noted that for site SI29 there was a

discrepancy with respect to one female and one male specimen and

concluded that he had corrected the sex for one individual. His

dissertation revealed 14 specimens for sites PP28 and MA30, whereas the

Service data includes 13 specimens for site PP28 and 15 for site MA30.

Atwood believes that this discrepancy was the result of correctly

placing one specimen in site MA30 rather than PP28. These two

corrections resulted in apparent discrepancies. Atwood was unable to

explain an additional discrepancy, in his dissertation he reported 19

female specimens for site SD24, whereas the data provided to the

Service indicates 20 female specimens for site SD24; Atwood suggested

that a typographical error had occurred.

Atwood discovered numerous discrepancies between the sample sizes

for his monograph (Atwood 1988) and the data given to the Service

(amounting to 15 more male specimens and 7 fewer female specimens

reported in the Service data set). Atwood could not conclusively

explain these [[Page 15695]] discrepancies, but suspected that they

were associated with the differing lengths of data set lines that may

have caused the SAS program to skip lines or combine lines of data. He

suggested that this problem may also have affected his analyses of the

data presented in the 1988 monograph. He indicated that because of

these potential problems, he felt that it is inappropriate to rely upon

the 1988 monograph with respect to subspecific conclusions, although

the conclusions with respect to species were unaffected, and are valid.

However, programming errors would not have affected the original data

set.

Atwood (in litt. 1994a,b) has acknowledged that one of the 213

samples in the data set provided to the public was not used in his 1991

study or in his previous, unpublished status review of the gnatcatcher.

Atwood (in litt. 1994b) believes that the excluded specimen was that

designated YP2717, an aberrant specimen (possibly a black-tailed

gnatcatcher or interspecies hybrid) collected in 1885. In Atwood's

subsequent reanalysis of the original data set, specimen YP2717 was

excluded from the data set because it differed from its sample area

mean by more than 3 standard deviations (Atwood in litt. 1994b).

The sample size discrepancies for all reports, except the 1988

monograph, are very minor, and would not have affected the overall

conclusions of the authors. Atwood (1994b) has characterized the

analysis of his 1988 monograph as being ``seriously flawed'' with

respect to data processing. The sample size discrepancies between

Atwood's other reports, and the 1988 monograph are likely due to these

data processing problems, and not the result of changes made to the

data set. The Service, therefore, concludes that the data set provided

by Atwood to the Service adequately duplicates the data originally

written on paper forms.

Issue 2: One commenter noted that two of Atwood's publications

(1988 and 1991) were contradictory in that they proposed different

geographic ranges for the taxon of California gnatcatchers occurring in

the United States. This same commenter suggested that Atwood's (1991)

retraction of his original (1988) conclusions pertaining to the

subspecies taxonomy of the California gnatcatcher was prompted by his

desire to affect the listing of the species.

Service Response: While the record indicates that Atwood believes

that the listing of the coastal California gnatcatcher is warranted,

the record also indicates that Dr. Atwood's revised conclusion about

the subspecific geographic limits of Polioptila californica californica

resulted from his 1991 reanalysis of the data cited in his 1988

monograph. The (1988) monograph had received peer review critical of

its findings.

The Service receives dozens of petitions to list or delist species

each year. The Act requires the Service to conduct an independent

review of each of these petitions, and to make final decisions on the

basis of the best scientific data available. The motives of the

petitioners, as with commenters, are not relevant to the Service's

decisions on these issues.

Issue 3: Several commenters alleged fundamental flaws in the data

used by Atwood (1991) in generating his conclusions. In particular,

commenters suggested or concluded that the data appeared to be

incomplete, or non-random (i.e., ``censored''). Several commenters were

concerned that the variables were ``confounded'' (i.e., the effects of

two or more factors on a response variable could not be separated) due

to the age or condition of certain specimens. These commenters

indicated that for the northern sites nearly all specimens were

collected prior to 1940, and none of the specimens from the remaining

sites were collected prior to 1920. One commenter noted that a

potential exists for serious bias in the data due to specimen

``foxing'' (i.e., browning with age). Another commenter noted, citing

relevant published scientific literature, that body size and plumage

brilliance and iridescence can reflect variation in specimen condition.

Some of these commenters suggested that differences in characters among

sites may be the result of the age of the collection, and not the site

from which they were collected.

Service Response: On behalf of the Service, the National Biological

Service independently conducted a new analysis of Atwood's data (Link

and Pendleton in litt. 1994). Three additional independent analyses of

the data were also submitted during the comment period.

In response to one commenter's concern that the data appeared to be

a non-random sample of California gnatcatchers, the National Biological

Service (Newton, in litt. 1995) replied that although these are valid

concerns, they are not proof, as acknowledged by the commenter, that

Atwood's data are not representative. One commenting ornithologist who

was largely critical of Atwood's (1991) analyses nevertheless concluded

that ``[t]he data set gathered by Atwood was quite comprehensive and

included measurements from a large number of specimens throughout the

range of the species.'' In the Memorandum Opinion and Order filed May

2, 1994, the Court declared, citing the declaration of this

ornithologist, that ``it is not disputed that Atwood's means of

collecting data were proper.''

After noting the possible problem of the age of the specimen being

confounded with the collection site, the authors attempted to adjust

the data for year or month the data was collected. McDonald et al. (in

litt. 1994) removed specimens collected from May to September and thus

avoided problems associated with feather wear. Link and Pendleton (in

litt. 1994) adjusted several characters for month and year based on the

results of regression analyses. Messer (in litt. 1994) conducted two of

her analyses by limiting the specimens to those collected between 1920

and 1940, and 1980 to 1984. Link and Pendleton (in litt. 1994) were

cautious and indicated that they may not have removed all of the

confounding effects; however, they also indicated that they may have

over adjusted the data and removed differences due to sites.

After adjusting the data for year and month of collection, Link and

Pendleton (in litt. 1994) obtained results similar to the unadjusted

data. Messer (in litt. 1994) was able to classify the northern birds

from the southern birds using specimens collected from 1980 to 1984

correctly in 84 percent of the cases, and using birds collected from

1920 to 1940 in 94 percent of the cases. The results of McDonald et al.

(in litt. 1994) also yielded weak evidence of a break at 30 deg. north

latitude, even though they had removed birds collected during certain

months of the year. Atwood (in litt. 1994b) also had similar results

before and after he excluded the variable brightness of breast plumage

(a variable that would have changed as a specimen aged) from his

analysis.

Given the above considerations and results, the Service finds no

justification or cause for concluding that Atwood's data were

incomplete, censored, or otherwise inadequate. Further, the Service

concludes that the available information does not support the

hypothesis that the confounding of variables is responsible for

erroneous conclusions regarding perceived breaks in the morphology of

the coastal California gnatcatcher. The Service concludes that the

analysts took adequate care to remove the possible effects of

confounding of age of specimen and collection area.

Issue 4: The Service received four significant analyses and a

number of critiques of each of the analyses of Atwood's data. Each

commenter [[Page 15696]] attempted to answer a different question, and

consequently, each of the analyses used somewhat different statistical

techniques, and drew somewhat different conclusions. Some of the

commenters concluded that the clinal nature of the data would argue

against subspecies; or that a primary break occurs further south and

would argue that if there are subspecies, the boundary line should be

drawn further south in Baja California. Others argued that the data are

clumped (consistent with a subspecific break); or that the birds north

of 30 deg. north latitude are different from the birds south of 30 deg.

north latitude. The Service analyzed these reports to draw a conclusion

regarding whether the data support Atwood's 1991 conclusions.

Service Response: Several commenters produced new analyses of the

data provided by Atwood. Atwood (in litt. 1994b) also provided an

additional taxonomic analysis of the data. With the exception of Atwood

(in litt. 1994b), all of the authors (Messer in litt. 1994, Link and

Pendleton in litt. 1994, and McDonald et al. in litt. 1994) explicitly

stated that their expertise is in statistics, and that taxonomic

conclusions should be left to taxonomists. The Service has carefully

reviewed each of these analyses and critiques to examine the strengths

and the weaknesses of each approach. A summary of these analyses

follows.

Atwood (in litt. 1994b) presented a reanalysis of his data using

log10 transformations of 6 variables (bill length, tarsus length,

wing length, tail length, length of white spot on a tail feather

(retrix 6), and brightness of breast plumage). In one analysis, he

excluded the variable ``brightness of breast plumage'' because Mellink

and Rea (1994) found readings inconsistent, even when resampling a

single specimen. Atwood used a Tukey-Kramer method to conduct pairwise

comparisons of the sample area means. He also conducted a principal

components analysis (a method of determining how the data are

intercorrelated, and reducing intercorrelated data to a principal

component score) of the data and performed a cluster analysis on the

first two principal component scores as well as on the original

variables. Tail length, tail spot length, and brightness of breast

plumage varied significantly among sample areas (all P2 test was used to test the significance

of the results. Cluster analysis and discriminant coordinates were

computed on the individual specimens to see how the data was clumped.

Finally, they attempted to adjust the data for time effects (see issue

3 above).

Link and Pendleton (in litt. 1994) obtained similar results in each

of these tests. They concluded that the changes in the characters are

more representative of groupings than of gradual change. They

determined that, at least one break occurs north of site 5 (mean

latitude of site 5 is 29.5 deg. north latitude) and at least one break

occurs south of site 5. The use of MANOVA would reduce the likelihood

of Type 1 error (reporting differences that do not exist) that would

occur if you looked at each variable separately. The AIC is not prone

to overfitting, and can be used to determine the model that best fits

the data. The AIC does not have an associated statistical test for

significance, and therefore, the groups identified in this manner may

not represent actual groupings (Newton in litt. 1995). Though Newton

(in litt. 1995) also indicated that Atwood's (in litt. 1994b) cluster

analysis would have been more useful if he had used individual

specimens rather than group means, Link and Pendleton's (in litt. 1994)

cluster analysis did use individual specimens and yielded groups

similar to their MANOVA results, creating a stronger basis for their

conclusions.

Messer (in litt. 1994) examined whether the birds north of 30 deg.

north latitude can be distinguished from the birds south of 30 deg.

north latitude. She used multivariate discriminant analysis to classify

birds into northern and southern subgroups with the boundary set at

30 deg. north latitude. Discriminant analysis is used when one is

examining a categorical dependent variable (e.g., north or south of

30 deg. north or one of 9 sites) and metric independent variables

(e.g., measurements of gnatcatcher characteristics). Discriminant

analysis would test whether the means among groups are equal. Using

several subsets of the data (e.g., limiting years of collection to

remove time effects, or in developing a model with one set of data and

another to test the model), Messer (in litt. 1994) concluded that one

could correctly classify the birds as being from the northern or

southern areas with 86 to 92 percent accuracy.

McDonald et al. (in litt. 1994) conducted their analyses using

individual specimens, and estimated the latitude based upon the

locality description given by Atwood in his original data set. They

removed specimens collected from May through September to avoid data

problems due to feather wear and molting, and attempted to adjust some

data for year of collection. To examine how the data are

intercorrelated, they conducted principal components analysis on size,

color, and pattern variables separately. McDonald et al. (in litt.

1994) conducted Gabriel's sum of squares simultaneous test procedure on

the first principal component scores and on the original variables.

McDonald et al. (in litt. 1994) conducted an intervention analysis to

look for steps or breaks in the trends in means. In addition, they

conducted a discriminant function analysis to determine whether birds

could be correctly classified at various latitudes.

The results from the Gabriel's test indicated that there were

significant differences in means of the first principal component at

24 deg. north latitude, and that for some of the size variables there

was weak evidence for a trend in means at 28 deg. north latitude or

27 deg. north latitude. There was weak evidence for difference in the

means at 30.5 deg. north latitude for the first principal component for

color variables. The intervention analysis revealed a significant rate

of change for 4 of the 16 individual size variables (page 6) at 30 deg.

north latitude (P2 on the groupings identified in

their MANOVA analysis to determine if the means could be separated.

McDonald et al. (in litt. 1994) used Gabriel's method to determine

differences in means at selected latitudes. Each of these approaches

was successful in separating means among groups of gnatcatchers.

The investigators next examined whether there might be steps in

these changes, or whether one could correctly classify (or place) the

birds within these groups. Messer (in litt. 1994) conducted a

multivariate discriminant analysis and found that the birds could be

classified into a groups north and south of 30 deg. north latitude with

an error rate of about 10 percent. Link and Pendleton (in litt. 1994)

conducted a clustering analysis to group individual specimens into

clusters and examined the overlap between the clusters and the

groupings identified in the MANOVA. McDonald et al. (in litt. 1994)

conducted a discriminant function analysis to identify latitudes that

separate the range of the bird into 2 groups with minimal

misclassification rates. Each of these approaches showed a break in the

characters at 30 deg. north latitude, and was supportive of Atwood's

(1991) conclusions.

In a statistically pure sense, these methods are exploratory in

nature and were useful in identifying hypotheses that could be tested

with respect to the gnatcatcher. To formally test these hypotheses, an

investigator would need to make similar measurements on newly gathered

gnatcatcher specimens. Issue 5 below discusses the Service's response

to this point. However, it is important to understand that statistics

are a tool used to assist an investigator in drawing conclusions in

that they can help quantify uncertainties with respect to those

conclusions (Newton pers. comm. 1995). The investigator still needs to

evaluate the practical significance of results, and should not focus

exclusively on statistical significance (Abbott et al. 1985, Hair et

al. 1995, Mayr et al. 1953). Statistics do not remove or supplant the

need to make informed decisions with respect to any data set. Messer

(in litt 1994), Link and Pendleton (in litt. 1994), and McDonald et al.

(in litt. 1994) all explicitly recognized that taxonomic decisions

should be made by taxonomists.

The misclassification rates identified by Messer (in litt. 1994)

and McDonald et al. (in litt. 1994), and the overlap in many of the

characters show that these [[Page 15698]] groupings of gnatcatchers are

not entirely discrete. Abbott et al. (1985) noted that taxonomists

expect ``variation within species to involve either a continuum or at

least some continuity or overlapping between forms.'' If the groupings

of California gnatcatcher were entirely discrete, avian taxonomists

likely would have assigned these groupings to separate species. Mayr

(1970) defined subspecies as ``an aggregate of phenotypically similar

populations of a species inhabiting a geographic subdivision of the

range of a species and differing taxonomically from other populations

of the species.'' Mayr (1970) concluded that the magnitude of taxonomic

difference necessary to appropriately decide when subspecies should be

delimited ``can be determined only by agreement among working

taxonomists.''

Grinnell (1926), Phillips (1991), and Atwood (1991) identified

30 deg. north latitude as a boundary between Polioptila californica

(=melanura) subspecies. Recent work suggests that the southern boundary

of P. c. californica may be further north, near the international

boundary between the United States and Mexico (Mellink and Rea 1994).

Mellink and Rea (1994) placed the birds between the international

border and 30 deg. north latitude in a new subspecies. Atwood

identified another subspecific break south of 30 deg. north. McDonald

et al. (in litt. 1994) and Link and Pendleton (in litt. 1994) also

noted a break south of 30 deg. north latitude, consistent with Atwood's

(1991) conclusion of an additional subspecific break. The consensus

among working taxonomists supports recognition of P. c. californica,

albeit its range may be more restricted than that proposed by Atwood

(1991). Therefore, the Service concludes that a finding that 30 deg.

north latitude as the southern specific boundary of P. c. californica

is supported by the available scientific evidence. Until additional

taxonomic work is published and accepted by the ornithological

community, the Service will recognize 30 deg. north latitude as the

southern subspecific boundary of P. c. californica.

Issue 5: Several commenters stated that analyses of a newly

collected independent data sets should be done to clarify gnatcatcher

taxonomy or resolve differences of opinion among the various

commenters. One commenter urged the Service to ``dismiss the subspecies

issue for gnatcatchers (pending further study) and focus on the

management of U.S. populations.'' Another commenter concluded that ``a

rigorous analysis of both morphometric, reflectance, genetic, and other

chemical data are required to address the problem in the clearest

possible manner.'' Other commenters added that the gnatcatcher should

not be listed until the perceived taxonomic controversy is resolved.

Service Response: The Service fully endorses and encourages efforts

to assess and refine the taxonomic status of all species, including the

coastal California gnatcatcher, provided that any collection of

specimens associated with such efforts does not result in unacceptable

mortality or other impacts. However, in making listing determinations,

section 4(b) of the Act requires the Service to make its listing

decisions within set timeframes and requires the Service to base its

listing decisions on the best scientific and commercial data available

at the time of the decision. The Service is not authorized to delay

listing decisions until all studies of arguable utility are completed,

until scientific debate is exhausted, or until complete consensus

occurs. The Service cannot await the ``next study,'' which may or may

not occur and which may or may not be affirmed by the scientific

community through the appropriate peer review process.

Efforts to conduct further analysis on the taxonomy and subspecific

limits of the California gnatcatcher would be costly and time

consuming. One could seek additional museum records not analyzed by

Atwood, or could collect new specimens. Collecting new specimens could

result in unacceptably high mortality. Moreover, collecting new field

specimens prior to making a final decision on this issue is not

practical. Alternatively, investigators could capture birds in mist

nets and obtain these measurements from live individuals, which would

then be released. However, additional researchers would be unable to

verify the results by visiting a museum and repeating the measurements.

As stated above under issue 4, the Service was charged with evaluating

whether Atwood's data supported his conclusions, and not with carrying

out additional studies to remove any and all controversy surrounding

the taxonomy of the Polioptila californica subspecies.

Conclusion

The Service has been charged with scrutinizing data and conclusions

rendered by Atwood, and determining if his data support his

conclusions. The Act provides that the Service must render its

determination on the basis of the best scientific and commercial data

available. The Service has made a concerted effort to obtain and

accurately assess the best scientific and best commercial information

available regarding the taxonomy and range of the coastal California

gnatcatcher. As an integral part of this process, the Service's

statutory mandates and standard scientific protocol require that we

recognize and act in accordance with the concepts, conventions, and

practices of the scientific method. To this end, the Service must seek

and seriously consider (1) data and analysis published in peer

reviewed, scientific journals, (2) the opinions of recognized experts

in given scientific disciplines, and (3) the input of the interested

public.

In this effort the Service has reviewed the analyses of the data

used by Atwood in his 1988 and 1991 papers. The Service finds that the

conclusions reached by Atwood (1991) are reasonable, and are generally

supported by the additional analyses received.

Under any circumstances that pertain to the taxonomy of North

American bird species, the Service actively seeks the publications,

input and expert opinion of the American Ornithologists' Union (AOU)

and its constituent Committee on Classification and Nomenclature

(Committee). The Committee and its publication (Check-list of North

American Birds) are recognized by the Service, scientists, and

scientific organizations throughout the world as authorities on avian

taxonomy in North America. Although the AOU has formally published its

positions on the taxonomy of the California gnatcatcher and coastal

California gnatcatcher (American Ornithologists' Union 1957, American

Ornithologists' Union 1989), the Service, nonetheless, made a concerted

effort to solicit and receive the recent, unequivocal, expert opinion

of the Committee and its members. During a past, prescribed public

comment period, the Service received responses from four members of the

Committee (including the Committee chair). The Committee members were

unanimous in acknowledging that Polioptila californica californica is

currently accepted as a distinct subspecies and that its southern

distributional limit occurs at 30 deg. north latitude.

In addition to independently seeking and reviewing the best

scientific information available from expert sources pertaining to the

taxonomic status of coastal California gnatcatcher, the Service also

repeatedly solicited comments or suggestions from the public, other

concerned governmental agencies, the scientific community, industry,

and any other party interested in gnatcatcher taxonomy and all other

aspects of the listing decision. In [[Page 15699]] response to these

requests for comments, the Service received a wide variety of public

comments and opinions, which are discussed earlier in this notice.

The Service has carefully considered all public comments received,

separate and independent analyses of Atwood's data, the National

Biological Service's (Link and Pendleton in litt. 1994) analysis of the

data, subsequent review of all technical submittals from the National

Biological Service (Newton in litt. 1995) and other interested parties,

the existing scientific literature, and the information presented in

the final listing rule designating the gnatcatcher as threatened (58 FR

16742). As a result, the Service concludes that the taxonomy and

geographic limits of the coastal California gnatcatcher are as provided

by Grinnell (1926, 1928) van Rossem (1931), American Ornithologists'

Union (1931), Grinnell and Miller (1944), Friedmann (1957), American

Ornithologists' Union (1957), Paynter (1964), Garrett and Dunn (1981),

Atwood (1991), and Phillips (1991). All of these scientific, peer

reviewed, publications present conclusions or affirmations that the

gnatcatcher (Polioptila californica californica) is restricted to

coastal southern California and northwestern Baja California, Mexico,

from Los Angeles County (and formerly Ventura County) south to the

vicinity of El Rosario at about 30 deg. north latitude.

The Service determines that the coastal California gnatcatcher is a

distinct taxon and that its geographic range is that described and

considered in the final listing rule for the coastal California

gnatcatcher (58 FR 16742). Therefore, the coastal California

gnatcatcher shall remain classified as a threatened species for reasons

that are stated in the final rule to list the species (58 FR 16742).

References Cited

A complete list of all references cited herein is available upon

request from the U.S. Fish and Wildlife Service, Carlsbad Field Office

(see ADDRESSES above).

List of Subjects in 50 CFR Part 17

Endangered and threatened species, Exports, Imports, Reporting and

recordkeeping requirements, and Transportation.

Authority: The authority for this action is the Endangered

Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).

Authors

The primary authors of this notice are Loren R. Hays of the

Carlsbad Field Office (see ADDRESSES section), and Karla J. Kramer of

the U.S. Fish and Wildlife Service, Portland Regional Office, 911

Northeast 11th Ave., Portland, Oregon 97232-4181 (telephone 503/231-

6131).

Dated: March 22, 1995.

Mollie H. Beattie,

Director, U.S. Fish and Wildlife Service.

[FR Doc. 95-7549 Filed 3-23-95; 10:39 am]

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