# Injurious Wildlife Species; Listing Three Python Species and One Anaconda Species as Injurious Reptiles

> Briefs, arguments, decisions, and more.

URL: https://www.frixlaw.com/law-library/documents/fr%3A2012-1155

## Record

- **Collection:** Federal Register
- **Document type:** Rule
- **Published:** January 23, 2012
- **Citation:** 77 FR 3330

## Text

DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 16
RIN 1018-AV68
[FWS-R9-FHC-2008-0015; FXFR13360900000N5-123-FF09F14000]
Injurious Wildlife Species; Listing Three Python Species and One Anaconda Species as Injurious Reptiles

AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Final rule.

SUMMARY:

The U.S. Fish and Wildlife Service (Service) is amending its regulations under the Lacey Act to add
Python molurus
(which includes Burmese python
Python molurus bivittatus
and Indian python
Python molurus molurus
), Northern African python (
Python sebae
), Southern African python (
Python natalensis
), and yellow anaconda (
Eunectes notaeus
) to the list of injurious reptiles. By this action, the importation into the United States and interstate transportation between States, the District of Columbia, the Commonwealth of Puerto Rico, or any territory or possession of the United States of any live animal, gamete, viable egg, or hybrid of these four constrictor snakes is prohibited, except by permit for zoological, education, medical, or scientific purposes (in accordance with permit regulation) or by Federal agencies without a permit solely for their own use. The best available information indicates that this action is necessary to protect the interests of human beings, agriculture, wildlife, and wildlife resources from the purposeful or accidental introduction and subsequent establishment of these large nonnative constrictor snake populations into ecosystems of the United States.

DATES:

This rule becomes effective on March 23, 2012.

ADDRESSES:

This final rule and the associated final economic analysis, regulatory flexibility analysis, and environmental assessment are available on the Internet at
http://www.regulations.gov
under Docket No. FWS-R9-FHC-2008-0015. Comments and materials received, as well as supporting documentation used in preparing this final rule, are available on the Internet at
http://www.regulations.gov
under Docket No.

FWS-R9-FHC-2008-0015; they are also available for public inspection, by appointment, during normal business hours, at the South Florida Ecological Services Office, U.S. Fish and Wildlife Service, 1339 20th Street, Vero Beach, FL 32960-3559; telephone (772) 562-3909 ext. 256; facsimile (772) 562-4288.

FOR FURTHER INFORMATION CONTACT:

Supervisor, South Florida Ecological Services Office, U.S. Fish and Wildlife Service, 1339 20th Street, Vero Beach, FL 32960-3559; telephone (772) 562-3909 ext. 256
.
If you use a telecommunications device for the deaf (TDD), please call the Federal Information Relay Service (FIRS) at (800) 877-8339.

SUPPLEMENTARY INFORMATION:

Previous Federal Action

On June 23, 2006, the Service received a petition from the South Florida Water Management District (District) requesting that Burmese pythons be considered for inclusion in the injurious wildlife regulations under the Lacey Act (18 U.S.C. 42, as amended; the Act). The District was concerned about the number of Burmese pythons (
Python molurus bivittatus
) found in Florida, particularly in Everglades National Park and on the District's widespread property in South Florida.

The Service published a notice of inquiry in the
Federal Register
(73 FR 5784; January 31, 2008) soliciting available biological, economic, and other information and data on the
Python, Boa,
and
Eunectes
genera for possible addition to the list of injurious wildlife under the Act and provided a 90-day public comment period. The Service received 1,528 comments during the public comment period that closed April 30, 2008. We reviewed all comments received for substantive issues and information regarding the injurious nature of species in the
Python, Boa,
and
Eunectes
genera. Of the 1,528 comments, 115 provided economic, ecological, and other data responsive to the 10 specific questions in the notice of inquiry. Most individuals submitting comments responded to the notice of inquiry as though it was a proposed rule to list constrictor snakes in the
Python, Boa,
and
Eunectes
genera as injurious under the Act. As a result, most comments expressed either opposition or support for listing the large constrictor snakes species and did not provide substantive information. We considered the information provided in the 115 applicable comments in the preparation of the draft environmental assessment, draft economic analysis, and the proposed rule.

On March 12, 2010, we published a proposed rule in the
Federal Register
(75 FR 11808) to list
Python molurus
(which includes Burmese and Indian pythons), reticulated python (
Broghammerus reticulatus
or
Python reticulatus
), Northern African python (
Python sebae
), Southern African python (
Python natalensis
), boa constrictor (
Boa constrictor
), yellow anaconda (
Eunectes notaeus
), DeSchauensee's anaconda (
Eunectes deschauenseei
), green anaconda (
Eunectes murinus
), and Beni anaconda (
Eunectes beniensis
) as injurious reptiles under the Act. The proposed rule established a 60-day comment period ending on May 11, 2010, and announced the availability of the draft economic analysis and the draft environmental assessment of the proposed rule. At the request of the public, we reopened the comment period for an additional 30 days ending on August 2, 2010 (75 FR 38069; July 1, 2010).

For the injurious wildlife evaluation in this final rule, in addition to information used for the proposed rule, we considered a wide range of information, including: (1) Substantive comments from two public comment periods for the proposed rule, (2) comments from five peer reviewers, and (3) new information acquired by the Service. From this information, we determined that four of the nine proposed species warrant listing as injurious at this time. In addition, we made improvements to the supplementary information to support and explain this decision.

We present a summary of the peer review comments and the public comments following the Lacey Act Evaluation Criteria section for four of the nine proposed species. The explanations in the sections on biology and evaluation of the four species will make many of the answers to the comments self-evident.

A major source of biological, management, and invasion risk information that we used for the proposed rule and this final rule was derived from the United States Geological Survey's (USGS) “Giant Constrictors: Biological and Management Profiles and an Establishment Risk Assessment for Nine Large Species of Pythons, Anacondas, and the Boa Constrictor” hereafter referred to as “Reed and Rodda 2009.” This document was prepared at the request of the Service and the National Park Service; it can be viewed at the following Internet sites:
http://www.regulations.gov
under Docket No. FWS-R9-FHC-2008-0015 and

http://www.fort.usgs.gov/Products/

Publications/pub_abstract.asp?PubID=22691

.

After full consideration of public comments and relevant factors, the Service is moving forward with publication of a final rule for the four species (Burmese python [including Indian python], Northern African python, Southern African python, and yellow anaconda. Five additional species (reticulated python, DeSchauensee's anaconda, green anaconda, Beni anaconda, and boa constrictor) are not being listed at this time and remain under consideration.

Background

Purpose of Listing as Injurious

The purpose of listing the Burmese python and its conspecifics (that is, belonging to the same species; hereafter referred to collectively as Burmese pythons unless otherwise noted),

Northern African python (
Python sebae
), Southern African python (
Python natalensis
), and yellow anaconda (
Eunectes notaeus
) (hereafter, collectively the four large constrictor snakes) as injurious wildlife is to prevent the accidental or intentional introduction of and the possible subsequent establishment of populations of these snakes in the wild in the United States.

Why the Four Species Were Selected for Consideration as Injurious Species

The Service has had the authority to list species as injurious under the Act since the 1940s. However, we have been criticized for not listing species before they became a problem (Fowler
et al.
2007). The Burmese python-the subject of the original petition here-is one example of a species that may not have become so invasive in Florida if it had been listed before it had become established. With this final rule, we are attempting to prevent the further spread of the Burmese python and the specified other large constrictor snakes into other vulnerable areas of the United States.

Furthermore, we have the authority under the Act to list wild mammals, wild birds, reptiles, amphibians, fish, mollusks, and crustaceans that are injurious even if they are not currently in trade or known to exist in the United States. Thus, we can be proactive and not wait until a species is already established. As noted in the National Invasive Species Management Plan (National Invasive Species Council 2008), “prevention is the first line of defense” and “can be the most cost-effective approach because once a species becomes widespread, controlling it may require significant and sustained expenditures.” This is why we are listing one species that is not yet found in the United States but which has the requisite injurious traits.

Two of the four largest snakes in the world (with maximum lengths well exceeding 6 m [20 ft]) are the Burmese python and Northern African python; both are present in international trade (although imports of the Burmese python are higher than those of the Northern African python). The Burmese python and the Northern African python are established in south Florida. The Northern and Southern African pythons are closely related and have similar appearances. While the Northern African python is documented on import records as being imported and the Southern African python is not, we believe that some snakes reported as Northern African pythons may have actually been Southern, and that importers may want to switch to the next most similar species (Southern) if the Northern African python became listed as injurious. Thus, we evaluated the Southern African python on its own traits.

None of the four species is native to the United States. The Service is striving to prevent the introduction and establishment of all four species into new areas of the United States, due to concerns about the injurious effects of all four species, consistent with 18 U.S.C. 42.

All four species were evaluated and found to be injurious because there is a suitable climate match in parts of the United States to support them; they are likely to escape captivity; they are likely to prey on and compete with native species (including threatened and endangered species); it would be difficult to prevent, eradicate, or reduce large populations; and other factors that are explained in the sections Factors That Contribute to Injuriousness for Burmese Python and for the other three species. All four species were placed in the highest category of overall risk in Reed and Rodda's report (2009) evaluating the risks of the nine proposed species.

Need for the Final Rule

Under the Lacey Act, the Secretary of the Interior is authorized to prescribe by regulation those wild mammals, wild birds, fish, mollusks, crustaceans, amphibians, reptiles, and the offspring or eggs of any of the foregoing that are injurious to human beings, to the interests of agriculture, horticulture, or forestry, or to the wildlife or wildlife resources of the United States, including the District of Columbia, the Commonwealth of Puerto Rico, or any territory or possession. We have determined that these four species of large constrictor snakes are injurious.

Thousands of Burmese pythons are now established in the Everglades and preying on many imperiled species and other wildlife. In addition, Northern African pythons are known to be established and breeding in South Florida. Yellow anacondas have also been reported in the wild in Florida. Burmese pythons, African pythons, and yellow anacondas have been reported in the wild in Puerto Rico. The Southern African python exhibits many of the same biological characteristics as the Northern African python that poses a risk of establishment and negative effects in the United States. The threat posed by the Burmese python and the three other large constrictor snakes will be explained in detail below under Factors That Contribute to Injuriousness for Burmese Python and each of the other species.

The USGS risk assessment used a method called “climate matching” to estimate those areas of the United States exhibiting climates similar to those experienced by the species in their respective native ranges (Reed and Rodda 2009). Considerable uncertainties exist about the native range limits of many of the giant constrictors, and a myriad of factors other than climate can influence whether a species could establish a population in a particular location. Nonetheless, this method represents the most accurate means to predict and anticipate where a nonnative species would be able to survive and establish populations within the United States.

Some interested parties, including other scientists such as Pyron
et al.
(2008), criticized Reed and Rodda's (2009) climate-matching method. In response, the authors published a clarification of how they used the model (Rodda
et al.
2011). This paper more clearly explained Reed and Rodda's (2009) method and compared that method to Pyron
et al.'
s (2008) method for analyzing potential invasiveness for the Burmese python. We mention a few of Rodda
et al.'
s (2011) findings here:

• Pyron
et al.
(2008) incorrectly rejected many sites that are suitable for Burmese python invasion because their use of an excessive number of parameters actually ended up acting as filters. Using too many filters means that too many sites that are truly at risk of python introduction get filtered out.

• Additionally, in the new paper the authors eliminated four data points of blood pythons (a different species than Burmese pythons) that Pyron
et al.
(2008) used erroneously. This

significantly changed the area that Burmese pythons could invade, even using the MaxEnt computer program as Pyron
et al.
(2008) used it.

• Information theory suggests 10 parameters as the appropriate number to use in a study like this; the Pyron
et al.
(2008) model, however, used 60. With this number the parameters essentially become constraints, and skew the accuracy of the data so that the resulting model is not scientifically sound.

• The new USGS paper highlights the statistical dangers inherent in indiscriminately searching for correlations among a large number of possible parameters.

• Factors other than climate may limit a species' native distribution, including the existence of predators, diseases, and other local factors (such as major terrain barriers), which may not be present when a species is released in a new country. Therefore, the areas at risk of invasion often span a climate range greater than that extracted mechanically from the native range boundaries, as was done by Pyron
et al.
(2008).

The new paper does not change the previous USGS risk assessment, or the Service's interpretation of the USGS risk assessment, that Burmese pythons could find suitable climatic conditions in roughly a third of the United States.

While we acknowledge that uncertainty exists, these tools also serve as a useful predictor to identify vulnerable ecosystems at risk from injurious wildlife prior to the species actually becoming established (Lodge
et al.
2006). Based on climate alone, many species of large constrictors are likely to be limited to the warmest areas of the United States, including parts of Florida, extreme south Texas, Hawaii, and insular territories. For a few species, larger areas of the southern United States appear to have suitable climatic conditions according to Reed and Rodda's (2009) climate-matching method.

The record cold temperatures in South Florida during January of 2010 produced the coldest 12-day period since at least 1940, according to the National Weather Service in Miami (NOAA 2010). A record low was set for 12 consecutive days with the temperature at or below 45 °F (7.2 °C) in West Palm Beach and Naples. Other minimum temperatures were broken in Moorehaven, tied in Fort Lauderdale, and the coldest in Miami since 1940. Despite the record cold, we know that many pythons survived in Florida. Large constrictors of several species continue to be present and to breed in south Florida. If thermoregulatory behavior or tolerance to cold is genetically based, we would expect large constrictor snake populations to persist, rebound, and possibly increase their genetic fitness and temperature tolerance as a result of natural selection pressures resulting from cold weather conditions such as those that occurred in south Florida in January 2010 (Dorcas
et al.
2011).

Two studies by scientists from several research institutions, including the University of Florida, studied the effects of the 2010 winter cold weather on Burmese pythons. In Mazzotti
et al.
2010, the authors noted that all populations of large-bodied pythons and boa constrictors inhabiting areas with cool winters, including northern populations of Burmese pythons in their native range, appeared to rely on use of refugia (safe locations) to escape winter temperatures. Pythons can seek such refugia as underground burrows, deep water in canals, or similar microhabitats to escape the cold temperatures. Those snakes that survived in Florida were apparently able to maintain body temperatures using microhabitat features of the landscape (Mazzotti
et al.
2010).

Dorcas
et al.
(2011) studied the cold tolerance of Burmese pythons taken directly from the Everglades and placed in enclosures in South Carolina. While all of the snakes in this study died, the Service finds the risk to more temperate regions still of concern and a listing of this species as an injurious species is still warranted. The authors state that their results suggest that Burmese pythons from the population currently established in Florida are capable of withstanding conditions substantially cooler that those typically experienced in southern Florida, but may not be able to survive severe winters in regions as temperate as central South Carolina. They noted that some snakes currently inhabiting Florida could survive typical winters in areas of the southeastern United States more temperate than the region currently inhabited by pythons. The authors also noted that, if thermoregulatory behavior is heritable, selection for appropriate thermoregulatory behavior will be strong as pythons expand their range northward through the Florida peninsula. Consequently, future generations of pythons may be better equipped to invade temperate regions than those currently inhabiting southern Florida, particularly given the climate flexibility exhibited by the Burmese python in its native range (as analyzed through USGS' climate-matching predictions in the United States).

The Service and Everglades National Park asked USGS to assess the risk of invasion of nine species of snakes to assist in the Service's determination of injuriousness. Of the nine large constrictor snakes assessed by Reed and Rodda (2009) (Burmese python (which the authors refer to as Indian python), reticulated python, Northern African python, Southern African python, boa constrictor, yellow anaconda, DeSchauensee's anaconda, green anaconda, and Beni anaconda), five were shown to pose a high risk to the health of the ecosystem, including the Burmese python, Northern African python, Southern African python, yellow anaconda, and boa constrictor. The remaining four large constrictors—the reticulated python, green anaconda, Beni anaconda, and DeSchauensee's anaconda—were shown to pose a medium risk. None of the large constrictors that the USGS assessed was classified as low overall risk. A rating of low overall risk is considered as acceptable risk and the organism(s) of little concern (ANSTF 1996). See Lacey Act Evaluation Criteria below for an explanation how USGS assessed risk.

There is a high probability that the four large constrictors evaluated in this final rule, if released or escaped into the wild, will establish populations within their respective thermal and precipitation limits due to common life-history traits that make them successful invaders. These traits include being habitat generalists (able to utilize a wide variety of habitats) that are tolerant of urbanization and capacity to hunt and eat a wide range of size-appropriate vertebrates (reptiles, mammals, birds, amphibians, and fish; Reed and Rodda 2009). These large constrictors are highly adaptable to new environments and opportunistic in expanding their geographic range. Furthermore, since they are a novel (new to the system) predator at the top of the food chain, they can threaten the stability of native ecosystems by altering the ecosystem's form, function, and structure.

These four species are cryptically marked, which makes them difficult to detect in the field, complicating efforts to identify the range of populations or deplete populations through visual searching and removal of individuals. There are currently no tools available that would appear adequate for eradication of an established population of giant snakes once they have spread over a large area. Therefore, preventing the introduction into the United States and dispersal to new areas of these invasive species is of critical importance to the health and welfare of native wildlife.

For the purposes of this rule, a hybrid is any progeny from any cross involving parents of one or more species from the four constrictor snakes evaluated in this rule. Such progeny are likely to possess the same biological characteristics of the parent species that, through our analysis, leads us to find that they are injurious to humans and to wildlife and wildlife resources of the United States. Anderson and Stebbins (1954) stated that hybrids may have caused the rapid evolution of plants and animals under domestication, and that, in the presence of new or greatly disturbed habitats, some hybrid derivates would have been at a selective advantage. Facon
et al.
(2005) stated that invasions may bring into contact related taxa that have been isolated for a long time. Facon
et al.
(2005) also stated that hybridization between two invasive taxa has been documented, and that in all these cases, hybrids outcompeted their parental taxa. Ellstrand and Schierenbeck (2000) concluded that dispersal of organisms and habitat disturbance by humans both act to accelerate the process of hybridization and increase the opportunities for hybrid lineages to take hold.

Furthermore, snakes in general have been found to harbor ticks (such as the nonnative African tortoise tick) that cause heartwater disease (from the bacterium
Cowdria ruminantium
). Heartwater disease, although harmless to its reptilian hosts, can be fatal to livestock and related wild hoofed mammals, such as white-tailed deer. According to the USDA (March 2000), “Heartwater disease is an acute, infectious disease of ruminants, including cattle, sheep, goats, white-tailed deer, and antelope. This disease has a 60 percent or greater mortality rate in livestock and a 90 percent or greater mortality rate in white-tailed deer.” The ticks have been found in Florida. Agricultural agencies are trying to stop the spread of the ticks as a way of stopping the deadly disease. This rule will help to stop the spread into and around the United States of the ticks and other disease vectors that may be carried by these four species of nonnative constrictor snakes.

Listing Process

The regulations contained in 50 CFR part 16 implement the Act. Under the terms of the Act, the Secretary of the Interior is authorized to prescribe by regulation those wild mammals, wild birds, fish, mollusks, crustaceans, amphibians, reptiles, and the offspring or eggs of any of the foregoing that are injurious to human beings, to the interests of agriculture, horticulture, or forestry, or to the wildlife or wildlife resources of the United States. The lists of injurious wildlife species are found at 50 CFR 16.11-16.15.

In this final rule, we evaluated each of the four species of constrictor snake species individually and determined each species to be injurious. As of the effective date of the listing, therefore, their importation into, or transportation between, the States, the District of Columbia, the Commonwealth of Puerto Rico, or any territory or possession of the United States by any means whatsoever is prohibited, except by permit for zoological, educational, medical, or scientific purposes (in accordance with permit regulations at 50 CFR 16.22), or by Federal agencies without a permit solely for their own use, upon filing a written declaration with the District Director of Customs and the U.S. Fish and Wildlife Service Inspector at the port of entry. This rule does not prohibit intrastate (within State boundaries) transport of the listed constrictor snake species. Any regulations pertaining to the transport or use of these species within a particular State will continue to be the responsibility of that State.

We used the Lacey Act Evaluation Criteria as a guide to evaluate whether a species does or does not qualify as injurious under the Act. The analysis developed using the criteria serves as a basis for the Service's regulatory decision regarding injurious wildlife species listings. A species does not have to be established, currently imported, or present in the wild in the United States for the Service to list it as injurious. The objective of such a listing would be to prevent that species' importation and likely establishment in the wild, thereby preventing injurious effects consistent with 18 U.S.C. 42.

Introduction Pathways for Large Constrictor Snakes

For the four constrictor snakes analyzed in this final rule, the primary pathway for the entry into the United States is the commercial pet trade. In the last few decades, most introductions of large constrictor snakes have been associated with the international trade in reptiles as pets. This trade includes wild-caught snakes, captive-bred, or captive-hatched juveniles from areas within their native countries. In their native ranges, a species may be captured in the wild and directly exported to the United States or other destination country, or wild-caught snakes may be kept in the country of origin to breed for export of subsequent generations. The main ports of entry for constrictor snakes are Miami, Los Angeles, Dallas-Ft. Worth, Baltimore, Detroit, Chicago, San Francisco, and Houston. From there, many of the live snakes are transported to animal dealers, who then transport the snakes to pet retailers. Large constrictor snakes are also bred in the United States and sold within the country.

A typical pathway of a large constrictor snake includes a pet store. Often, a person will purchase a hatchling snake (0.55 meters (m) [(22 inches (in)]) at a pet store or reptile show for as little as $25. The hatchling grows rapidly, even when fed conservatively, so a strong escape-proof enclosure is necessary. All snakes are adept at escaping, and constrictors are especially powerful when it comes to breaking out of cages. In captivity, they are most frequently fed pre-killed mice, rats, rabbits, and chickens. A tub of fresh water is needed for the snake to drink and soak in. As the snake grows too big for a tub in its enclosure, the snake will need to soak in increasingly larger containers, such as a bathtub. Under captive conditions, pythons will grow very fast. After 1 year, a python may be 2 m (7 ft) and after 5 years it could be 7.6 m (25 ft), depending on how often it is fed and other aspects of husbandry. A Burmese python, for example, will grow to more than 6 m (20 ft) long, weigh 90 kilograms (kg; 200 pounds (lbs)), live more than 25 years, and must be fed rabbits and the like.

Owning a giant snake is a difficult, long-term, and somewhat expensive responsibility. This is one reason that some snakes are released by their owners into the wild when they can no longer care for them. Other snakes may escape from inadequate enclosures. This is a common pathway for large constrictor snakes to enter the ecosystem (Fujisaki
et al.
2009). The trade in constrictor snakes is international as well as domestic. From 1999 to 2010, more than 1.9 million live constrictor snakes of 12 species were imported into the United States (U.S. Fish and Wildlife Service 2011). Besides the species proposed for listing, these included ball python (
Python regius
), a blood python (
P. curtus
), another blood python (
P. brongersmai
), Borneo python (
P. breitensteini
), Timor python (
P. timoriensis
), and Angolan python (
P. anchietae
), none of which have been proposed for listing as injurious. From 1999 to 2010, approximately 96,000 large constrictor snakes of four species listed by this rule were imported into the United States (Service's final economic analysis 2012). Of all the constrictor snake species imported into the United States, the selection of nine constrictor snakes for evaluation as

injurious wildlife in the proposed rule was based on concern over the giant size of these particular snakes combined with their quantity in international trade or their potential for trade. The world's four largest species of snakes (Burmese python, Northern African python, reticulated python, and green anaconda) were selected, as well as similar and closely related species and the boa constrictor. These large constrictor snakes constitute a high risk of injuriousness in relation to those taxa with lower trade volumes; are massive, with maximum lengths exceeding 6 m (20 ft; except for boas up to 4 m (13 ft)); and have a high likelihood of establishment in various habitats of the United States. The Southern African python and yellow anaconda exhibit many of the same biological characteristics associated with a risk of establishment and negative effects in the United States.

The strongest factor influencing the chances of these large constrictors establishing in the wild are the number of release events and the numbers of individuals released (Bomford
et al.
2009; 2005). A release event is when a nonnative species is either intentionally or unintentionally let loose in the wild. With a sufficient number of either intentional or unintentional release events, these species will likely become established in ecosystems with suitable conditions for survival and reproduction. For nonnative species to cause economic or ecological harm, they must first be transported out of their native range and released within a novel locality, establish a self-sustaining population in this new location, and expand their geographical range beyond the point of initial establishment. Releases of large numbers of individuals should enable the incipient (newly forming), nonnative population to withstand the inevitable decreases in survival or reproduction caused by the environment or demographic accidents. The release of many individuals into one location essentially functions as a source pool of immigrants, thus sustaining an incipient population even if the initial release was of insufficient size (or badly timed) to facilitate long-term establishment. Natural disasters, such as Hurricane Andrew in 1992, may have provided a mechanism for the accidental release of snakes, especially in light of large numbers of juvenile pythons frequently held by breeders and importers prior to sale and distribution (Willson
et al.
2010).

Large or consistent releases of individuals into one location should enable the incipient population to overcome behavioral limitations or other problems associated with small population sizes. This is likely the case at Everglades National Park, where the core nonnative Burmese python population in Florida is now located. Therefore, allowing unregulated importation and interstate transport of these nonnative species will increase the risk of these new species becoming established through increased opportunities for release. The release of large constrictor snakes at different times and locations improves the chance of their successful establishment.

Released snakes may be single snakes that eventually find other snakes of the same or opposite sex. As a first step in understanding the ecology of these snakes and their potential impact on the Everglades ecosystem, the National Park Service began tracking pythons using radio-telemetry in the fall of 2005. The radio-tagged pythons have since demonstrated that female pythons make few long-distance movements throughout the year, while males roam widely in search of females during the breeding season (December-April). These results indicate an ability to move long distances in search of prey and mates. Pythons have a “homing” ability: after being released far from where they were captured, they returned long distances (up to 78 kilometers (km); 48 miles (mi)) in only a few months. These findings suggest that pythons searching for a suitable home range have the potential to colonize areas far from where they were released (Snow 2008; Harvey
et al.
2008).

A second factor that is strongly and consistently associated with the success of an invasive species' establishment is a history of the species successfully establishing elsewhere outside its native range. Burmese pythons have already become established in the United States (see
Current Nonnative Occurrences
for Burmese python below). Therefore, we know that Burmese pythons can become established outside of their native range. The Northern African python is established west of Miami, Florida, in the vicinity known as the Bird Drive Basin Recharge Area (see
Current Nonnative Occurrences
for Northern African python below). Therefore, we know that Northern African pythons can also establish outside of their native range.

A third factor strongly associated with establishment success is having a good climate or habitat match between where the species naturally occurs and where it is introduced. Exotic (nonnative) reptiles and amphibians have a greater chance of establishing if they are introduced to an area with a climate that closely matches that of their original range. Species that have a large range over several climatic zones are predicted to be strong future invaders. The suitability of a country's climate for the establishment of a species can be quantified on a broad scale by measuring the climate match between that country and the geographic range of a species. Climate matching only sets the broad parameters for determining if an area is suitable for a nonnative large constrictor snake to establish. These three factors have all been consistently demonstrated to increase the chances of establishment by all invasive vertebrate taxa, including the four large constrictor snakes in this final rule (Bomford 2008, 2009).

However, as stated above, a species does not have to be established, currently imported, or present in the wild in the United States for the Service to determine that it is injurious. The objective of such a listing is to prevent that species' importation and likely establishment in the wild, thereby preventing injurious effects consistent with 18 U.S.C. 42.

Species Information

Burmese Python (Python molurus, Including Indian Python)

Native Range

Before laying out the native range of the Burmese python, we need to clarify our position on the taxonomy and nomenclature of this species. The taxonomy has been debated for almost 100 years, some scientists arguing for full species status for the Burmese python and some placing it as a subspecies of the Indian python. Reed and Rodda (2009) stated that, at times,
Python molurus
has been divided into subspecies recognizable primarily by color. Please see our response to Peer Review comment 3 (
PR3
) below for a detailed explanation of the taxonomic debate and our rationale for using
Python molurus
to include Burmese and Indian pythons. For the reasons stated in that response, we have no basis to assume that the ecological behavior of Burmese python
P. m. bivittatus
is independent of that of Indian python
P. m. molurus.
Furthermore, even a finding of ecological independence of
P. m. bivittatus
would not appreciably alter either the likelihood of its establishment in the United States or the cold tolerance of the whole species
Python molurus,
which was the taxon analyzed in the risk assessment (Reed and Rodda 2009; G. Rodda, pers. comm. 2009). Therefore, for the purposes of this rulemaking, the Service has determined that the Burmese python

should be able to survive in relatively similar conditions as the Indian python.

The nomenclature of
Python molurus
varies somewhat as well. The most widely used common name for the entire species
P. molurus
is Indian python, with
P. molurus bivittatus
routinely distinguished as the Burmese python. Other common names include Indian rock python, Asian rock python, and rock python. Because the pet trade is composed almost entirely of
P. m. bivittatus,
most popular references simply use Burmese python. In addition, the subspecies
Python m. molurus
is listed as endangered in its native lands under the Endangered Species Act of 1973, as amended (16 U.S.C. 1531
et seq.
) under the common name of Indian python.
Python m. molurus
is also listed by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) under Appendix I (which “lists species that are the most endangered among CITES-listed animals and plants”) but uses no common name. Except for
Python m. molurus,
which, as just stated, is listed in Appendix I, all species and subspecies of
Pythonidae
are listed in CITES Appendix II (which “lists species that are not necessarily now threatened with extinction but that may become so unless trade is closely controlled”). This rule lists all members of
Python molurus
as injurious under the Lacey Act. However, hereafter in this rule, we refer to the species as a whole under the common name of Burmese python (unless specifically noted as Indian), because of its occurrence in trade.

Python molurus
ranges widely over southern and southeastern Asia (Reed and Rodda 2009). In its native range, the Burmese python occurs in virtually every habitat from lowland tropical rainforest (Indonesia and southeastern Asia) to thorn-scrub desert (Pakistan) and grasslands (Sumbawa, India) to warm, temperate, montane forests (Nepal and China) (Reed and Rodda 2009). This species inhabits an extraordinary range of climates, including both temperate and tropical, as well as both very wet and very dry environments (Reed and Rodda 2009).

Biology

The Burmese python's life history is fairly representative of large constrictors because juveniles are relatively small when they hatch, but nevertheless are independent from birth, grow rapidly, and mature in a few years. Mature males search for mates, and the females wait for males to find them during the mating season, then lay eggs to repeat the cycle. Female Burmese pythons do not need to copulate with males to fertilize their eggs. Instead, a female apparently can fertilize her own eggs with her own genetic material, though it is not known how often this occurs in the wild. Several studies of captives reported viable eggs from females kept for many years in isolation (Reed and Rodda 2009).

Like all pythons, the Burmese python is oviparous (lays eggs). In a sample of eight clutches discovered in southern Florida (one nest and seven gravid females), the average clutch size was 36 eggs, but pythons have been known to lay as many as 107 eggs in one clutch. Adult females from recent captures in Everglades National Park have been found to be carrying more than 85 eggs (Harvey
et al.
2008).

The Burmese python is one of the largest snakes in the world, considering overall mass and length; it reaches lengths of up to 7 m (23 ft) and weights of over 90 kg (almost 200 lbs). Hatchlings range in length from 50 to 80 centimeters (cm) (19 to 31 inches (in)) and can more than double in size within the first year (Harvey
et al.
2008). As with all snakes, pythons grow throughout their lives (Reed and Rodda 2009). Reed and Rodda (2009) cite Bowler (1977) for two records of captive Burmese pythons living more than 28 years (up to 34 years, 2 months for one snake that was already an adult when acquired).

Like all of the large constrictors, Burmese pythons are extremely cryptic in coloration. They are silent hunters that lie in wait along pathways used by their prey and then ambush them; they kill by wrapping their muscular bodies around their victims, squeezing tighter as the prey exhales until the victims suffocate. The snakes blend into their surroundings so well that observers have released marked snakes for research purposes and lost sight of them 5 feet away (A. Roybal, pers. comm. 2010).

With only a few reported exceptions, Burmese pythons eat a wide variety of terrestrial vertebrates (lizards, frogs, crocodilians, snakes, birds, and mammals). All constrictor snake species (especially the smaller-sized individuals) are capable of climbing trees to access roosting birds and bats. Many birds nest or feed on the ground, and these are easy prey for constrictor snakes. Special attention has been paid to the large maximum size of prey taken from python stomachs, both in their native range in Asia and in the United States. The most well-known large prey items include alligators, antelopes, dogs, deer, jackals, goats, porcupines, wild boars, pangolins, bobcats, pea fowl, frigate birds, great blue herons, langurs, and flying foxes; a leopard has even been reported as prey (Reed and Rodda 2009). To accommodate the large size of prey, Burmese pythons have the ability to grow stomach tissue quickly to digest a large meal (Reed and Rodda 2009). The methods of predation used by the Burmese python (whether sit-and-wait or actively hunting, or whether diurnal or nocturnal), as well as the other three species of large constrictor snakes in this final rule, work as well in their native ranges as in the United States.

Ectoparasites (including ticks of the genus
Amblyomma)
were collected from wild-caught, free-ranging exotic reptiles examined in Florida from 2003 to 2008 (Corn
et al.
2011). This was the first report of collections of neotropical ticks from wild-caught Burmese pythons. From limited wild-caught, free-ranging exotic reptiles in Florida (including ball and Burmese pythons), ticks and mites were native to North America, Latin America, and Africa from reptiles native to Asia, Africa, and Central and South America. This study suggests the diversity of reptile ectoparasites introduced and established in Florida and the new host-parasite relationships that have developed among exotic and native ectoparasites and established exotic reptiles. Several studies (Burridge
et al.
2000, Kenny
et al.
2004, Reeves
et al.
2006) have shown disease agents in the ticks that travel internationally on reptiles, which may serve in the introduction of disease agents that could impact the health of local wildlife, domestic animals, and humans (Corn
et al.
2011).

Northern African Python (Python sebae)

Native Range

Python sebae
and
Python natalensis
are closely related, large-bodied pythons of similar appearance found in sub-Saharan Africa (Reed and Rodda 2009). The most common English name for this species complex has been African rock python. After
P. sebae
was split from
P. natalensis,
some authors added “Northern” or “Southern” as a prefix to this common name. Reed and Rodda (2009) adopted Broadley's (1999) recommendations and refer to these snakes as the Northern and Southern African pythons; hereafter, we refer to them as Northern and Southern African pythons, or occasionally as African pythons or African rock pythons.

Northern African pythons range from the coasts of Kenya and Tanzania across much of central Africa to Mali and Mauritania, as well as north to Ethiopia and perhaps Eritrea; in arid zones, their range is apparently limited to the

vicinity of permanent water (Reed and Rodda 2009). In Nigeria, Northern African pythons are reported from suburban, forest, pond and stream, and swamp habitats, including extensive use of Nigerian mangrove habitats. In the arid northern parts of its range, Northern African pythons appear to be limited to wetlands, including the headwaters of the Nile, isolated wetlands in the Sahel of Mauritania and Senegal, and the Shabelle and Jubba Rivers of Somalia (Reed and Rodda 2009). The Northern African python inhabits regions with some of the highest mean monthly air temperatures identified for any of the large constrictors, with means of greater than 35 °C (95 °F) in arid northern localities (Reed and Rodda 2009).

Biology

Northern African pythons are primarily ambush foragers, lying in wait for prey in burrows, along animal trails, and in water. Northern African pythons are oviparous. Branch (1988) reports that an “average” female of 3 to 4 m (10 to 13 ft) total length would be expected to lay 30 to 40 eggs, while others report an average clutch of 46 eggs, individual clutches from 20 to “about 100,” and clutch size increasing correspondingly in relation to the body length of the female (Pope 1961). In captivity, Northern African pythons have lived for 27 years (Snider and Bowler 1992). As with most of the large constrictors, adult African pythons primarily eat endothermic (warm-blooded) prey (mammals and birds) from a wide variety of taxa. African pythons have consumed such animals as goats, dogs, and domestic turkeys.

Southern African Python (
Python natalensis
)

Native Range

The Southern African python is found from Kenya southwest to Angola and south through parts of Namibia and much of eastern South Africa. Distribution of the species overlaps somewhat with Northern African pythons, although the southern species tends to inhabit higher elevations in regions where both species occur (Reed and Rodda 2009).

Biology

Python sebae
and
Python natalensis
are closely related, large-bodied pythons of similar appearance. In fact, taxonomists have lumped and split the species together several times since
Python natalensis
was described (Reed and Rodda 2009); see “
Native Range”
section above under “Northern African Python (
Python sebae
)” for further explanation of the nomenclature.

Little is known about Southern African pythons, although we know that they are oviparous. As with most of the large constrictors, adult African pythons primarily eat endothermic prey from a wide variety of taxa. The Southern African pythons consume a variety of prey types that includes those listed for Northern African pythons.

Yellow Anaconda (
Eunectes notaeus
)

Native Range

The yellow anaconda (
Eunectes notaeus
) has a larger distribution in subtropical and temperate areas of South America than the DeSchauensee's anaconda and has received more scientific attention. The yellow anaconda appears to be restricted to swampy, seasonally flooded, or riverine habitats throughout its range. The primarily nocturnal anaconda species tends to spend most of its life in or around water. The yellow anaconda exhibits a fairly temperate climate range, including localities with cold-season monthly mean temperatures around 10 °C (50 °F) and no localities with monthly means exceeding 30 °C (86 °F) in the warm season (Reed and Rodda 2009).

Biology

The yellow anaconda bears live young (ovoviviparous). The recorded number of yellow anaconda offspring usually range from 10 to 37, with a known maximum of 56. In captivity, yellow anacondas have lived for more than 20 years. These anacondas are considerably smaller than the closely related green anaconda. Female yellow anacondas from Argentina measured a maximum length of 3.8 m (12.5 ft) and maximum weight of 29 kg (69.9 lbs); males reached 2.93 m (9.6 ft) and 10.5 kg (23.1 lbs) (Reed and Rodda 2009). The largest yellow anacondas found in the wild were about 4 m (13.1 ft). They have been reported to exceed those measurements in captivity.

Yellow anacondas appear to be generalist predators (able to prey on a wide variety of vertebrates). The anacondas in general, including this species, exhibit among the broadest diet range of any snake, including ectotherms (cold-blooded animals: lizards, crocodilians, turtles, snakes, fish) and endotherms (birds, mammals).

Summary of the Presence of the Four Constrictor Snakes in the United States

Of the four constrictor snake species that we are listing as injurious, three have been reported in the wild in the United States and two have been confirmed as reproducing in the wild in the United States (see
Current Nonnative Occurrences
below); three have been imported commercially into the United States during the period 1999 to 2010 (Table 1). Species “reported in the wild” are ones that have been found in the wild but without proof to date that they have reproduced in the wild. The greatest opportunity for preventing a species from becoming injurious is to stop a species from entering the wild; the second greatest opportunity is before a species becomes established in the wild (reported but not reproducing); and the smallest opportunity is when a species has become established (reproducing in the wild).

Table 1—Four Species of Large Constrictor Snakes and Whether They Have Been Reported in the Wild in the United States, Are Known To Be Reproducing in the Wild in the United States, or Have Been Imported for Trade (1999 to 2010)

Species
Reported in the wild in U.S.?
Reproducing in the wild in U.S.?
Imported into U.S. for trade?*

Burmese python
Yes
Yes
Yes.

Northern African python
Yes
Yes ***
Yes.

Southern African python
No
No
Unknown.**

Yellow anaconda
Yes
No
Yes.

* Data from Law Enforcement Management Information System (LEMIS; USFWS 2011).
** It is possible that this species has been imported into the United States incorrectly identified as one of the other species listed by this rule; however none have been reported.

*** Reed
et al.
2010.

Lacey Act Evaluation Criteria

We use the criteria below to evaluate whether a species does or does not qualify as injurious under the Lacey Act, 18 U.S.C. 42. The analysis that is developed using these criteria serves as a general basis for the Service's regulatory decision regarding injurious wildlife species listings (not just for the four snake species being listed by this final rule). Biologists within the Service who are knowledgeable about a species being evaluated assess both the factors that contribute to and the factors that reduce the likelihood of injuriousness.

(1) Factors that contribute to being considered injurious:

• The likelihood of release or escape;

• Potential to survive, become established, and spread;

• Impacts on wildlife resources or ecosystems through hybridization and competition for food and habitats, habitat degradation and destruction, predation, and pathogen transfer;

• Impact to threatened and endangered species and their habitats;

• Impacts to human beings, forestry, horticulture, and agriculture; and

• Wildlife or habitat damages that may occur from control measures.

(2) Factors that reduce the likelihood of the species being considered as injurious:

• Ability to prevent escape and establishment;

• Potential to eradicate or manage established populations (for example, making organisms sterile);

• Ability to rehabilitate disturbed ecosystems;

• Ability to prevent or control the spread of pathogens or parasites; and

• Any potential ecological benefits to introduction.

To obtain some of the information for the above criteria, we referred to Reed and Rodda (2009). Reed and Rodda (2009) developed the Organism Risk Potential scores for each species using a widely utilized risk assessment procedure that was published by the Aquatic Nuisance Species Task Force, called “Generic nonindigenous aquatic organisms risk analysis review process (for estimating risk associated with the introduction of nonindigenous aquatic organisms and how to manage that risk)” (ANSTF 1996). The Aquatic Nuisance Species Task Force was created under the Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990 (NANPCA). Congress enacted NANPCA to provide a way for government agencies to develop a national program to reduce the risk of unintentional introductions, ensure prompt detection and response, and control established species.

The ANSTF (1996) procedure incorporates four factors associated with probability of establishment and three factors associated with consequences of establishment, with the combination of these factors resulting in an overall Organism Risk Potential (ORP) for each species. For the four constrictor snakes, the risk of establishment was high.

For the four constrictor snakes, the consequences of establishment range from medium (yellow anaconda) to high (Burmese python, Northern African python, and Southern African python). The overall ORP, which is derived from an algorithm of both probability of establishment and consequences of establishment, was found to be high for all four species.

Certainties were highly variable within each of the seven elements or factors of the risk assessment mentioned above, varying from very uncertain to very certain. In general, the highest certainties were associated with species unequivocally established in Florida (such as Burmese python and Northern African python) because of enhanced ecological information on these species from studies in both their native range and in Florida. The way in which these subscores are obtained and combined is set forth in an algorithm created by the ANSTF (Table 2).

Table 2—The Algorithm That the ANSTF (1996) Defined for Combining the Two Primary Subscores
[Reed and Rodda 2009].

Probability of establishment
Consequences of establishment
Organism Risk Potential (ORP)

High
High
High.

Medium
High
High.

Low
High
Medium.

High
Medium
High.

Medium
Medium
Medium.

Low
Medium
Medium.

High
Low
Medium.

Medium
Low
Medium.

Low
Low
Low.

Similar algorithms are used for deriving the primary subscores from the secondary subscores. However, the scores are fundamentally qualitative, in the sense that there is no unequivocal threshold that is given in advance to determine when a given risk passes from being low to medium, and so forth. Therefore, we viewed the process as one of providing relative ranks for each species. Thus, a high ORP score indicates that such a species would likely entail greater consequences or greater probability of establishment than would a species whose ORP was medium or low (that is, high > medium > low). High-risk species include the four species being designated as injurious by this rulemaking: Burmese pythons, Northern and Southern African pythons, and yellow anacondas. High-risk species, if established in this country, would put larger portions of the U.S. mainland and insular territories at risk, constitute a greater ecological threat, or are more common in trade and commerce.

Factors That Contribute to Injuriousness for Burmese Python

Current Nonnative Occurrences

The Burmese python has been captured in many areas in Florida (see Figure 5 in the final environmental assessment). In South Florida, more than 1,300 live and dead Burmese pythons, including gravid females, have been removed from in and around Everglades National Park in the last 11 years by authorized agents, park staff, and park partners, indicating that they are already established (National Park Service 2010). In the Commonwealth of Puerto Rico, the Burmese python has been collected or reported (eight individuals collected, including a 3-m (10-ft) albino) from the municipality of Adjuntas, the northern region of the island (Arecibo), the eastern region of the island (Humacao), and southeastern region of the island (Guayama) (A. Atienza, pers. comm. 2010; J. Saliva, pers. comm. 2009; USGS 2007).

Newspaper accounts from 1980 to 2010 report that numerous Burmese pythons have escaped captivity or were spotted in the wild in the following States (HSUS 2009; 2010): Arkansas, California, Georgia, Idaho, Illinois, Louisiana, Maryland, Michigan, Mississippi, Missouri, Montana, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, Tennessee, Utah, and Virginia. This illustrates that the potential for release or escape is not confined to Florida and Puerto Rico but could occur in many States. See the section “Introduction Pathways for Large Constrictor Snakes” for the explanation of how release events are relevant to the potential establishment of Burmese pythons.

Potential Introduction and Spread

The likelihood of release or escape from captivity of Burmese python is high as evidenced by the number of reports from Florida and Puerto Rico (National Park Service 2010; J. Saliva, pers. comm. 2009; HSUS 2010; USGS 2007). When Burmese pythons escape captivity or are released into the wild, many have survived and are likely to

continue to survive and become established with or without reproducing. For example, in the past 11 years, more than 1,300 Burmese pythons have been removed from just Everglades National Park and vicinity (National Park Service 2010), and others have been captured from other natural areas on the west side of South Florida, the Florida Keys (Higgins, pers. comm. 2009), and farther north on the peninsula, including Sarasota and Indian River County (M. Lowman, pers. comm. 2009; B. Dangerfield, pers. comm. 2010).

Moreover, released Burmese pythons would likely disperse to areas of the United States with a suitable climate. See “Introduction Pathways for Large Constrictor Snakes” section above for the explanation of how the snakes would spread. These areas were determined in the risk assessment (Reed and Rodda 2009) for all four constrictor snakes by comparing the type of climate the species inhabited in their native ranges to areas of similar climate in the United States (climate matching). Due to the wide rainfall tolerance and extensive semi-temperate range of Burmese python, large areas of the southern United States mainland appear to have a climate suitable for survival of this species. Areas of the United States that are climatically matched at present include along the coasts and across the south from Delaware to Oregon, as well as most of California, Texas, Oklahoma, Arkansas, Louisiana, Mississippi, Alabama, Florida, Georgia, and South and North Carolina. In addition to these areas of the U.S. mainland, the territories of Guam, Northern Mariana Islands, American Samoa, Virgin Islands, and Puerto Rico appear to have suitable climates. Areas of the State of Hawaii with elevations under about 2,500 m (8,202 ft) would also appear to be climatically suitable. Burmese pythons are highly likely to spread and become established in the wild due to common traits shared by the giant constrictors: Rapid growth to a large size with production of many offspring; ability to survive under a range of habitat types and conditions (habitat generalist); behaviors that allow escape from freezing temperatures; ability to adapt to live in urban and suburban areas; ability to disperse long distances (Harvey
et al.
2008); and tendency to be well-concealed ambush predators.

Potential Impacts to Native Species (Including Threatened and Endangered Species)

As discussed above under
Biology,
the Burmese python grows to lengths greater than 7 m (23 ft) and can weigh up to 90 kg (200 lbs). This is longer than any native terrestrial predator (including bears) in the United States and its territories and heavier than most native predators (including black bears). Burmese pythons can be so large that they can prey on alligators, which are among the largest native predators in the Southeast (Harvey
et al.
2008, Reed and Rodda 2009, National Geographic 2006).

In comparison with the Burmese python, the largest snake native to the continental United States is much smaller. The largest native snake is the indigo snake (
Drymarchon corais
),

attaining a maximum length of about 2.5 m (8 ft) (Monroe and Monroe 1968). The endangered Puerto Rican boa's (
Epicrates inornatus
) maximum size is approximately 2 m (6.5 ft) (U.S. Fish and Wildlife Service 1986). A subspecies of the indigo snake is the eastern indigo snake (
D. corais couperi
), which grows to a similar maximum length. The eastern indigo snake inhabits Georgia and Florida and is listed as federally threatened by the Service.

Unlike prey species in the Burmese python's native range, none of our native species has evolved defenses to avoid predation by such a large snake. Thus, native wildlife anywhere in the United States would be very likely to fall prey to Burmese pythons (or any of the other six constrictor snakes). At all life stages, Burmese pythons can and will compete for food with native species; in other words, baby pythons will eat small prey, and the size of their prey will increase as they grow. Based on an analysis of their diets in Florida, Burmese pythons, once they are introduced and established, may outcompete native predators (such as the federally listed Florida panther, eastern indigo snake, native boas, hawks), feeding on the same prey and thereby reducing the supply of prey for the native predators.

Burmese pythons are generalist predators that consume a wide variety of mammal and bird species, as well as reptiles, amphibians, and occasionally fish. This constrictor can easily adapt to prey on novel wildlife (species that they are not familiar with), and they need no special adaptations to hunt, capture, and consume them. Pythons in Florida have consumed prey as large as white-tailed deer and adult American alligators. Three federally endangered Key Largo woodrats (
Neotoma floridana smalli
) were eaten by a Burmese python in the wild in the Florida Keys in 2007. The extremely small number of remaining Key Largo woodrats suggests that the current status of the species is precarious (U.S. Fish and Wildlife Service 2008); this means that a new predator that has been confirmed to prey on the endangered woodrats is a serious threat to the continued existence of the species. Dove
et al.
(2011) found 25 species of birds representing 9 avian orders from remains in digestive tracts of 85 Burmese pythons (
Python molurus bivittatus
) collected in Everglades National Park; this included the federally endangered wood stork and 4 species of State concern.

The United States, particularly the Southeast, has a diverse faunal community that is potentially vulnerable to predation by the Burmese python. Juveniles of these large constrictors will climb trees and rocks to remove prey from bird nests and capture perching or sleeping birds. Most of the South has suitable climate and habitat for Burmese pythons. The greatest biological impact of an introduced predator, such as the Burmese python, is the likely loss of imperiled native species. Based on the food habits and habitat preferences of the Burmese python in its native range, the species is likely to invade the habitat, prey on, and further threaten most of the federally threatened or endangered fauna in climate-suitable areas of the United States.

Burmese pythons are also likely to decrease the populations of numerous potential candidates for Federal protection by hunting and eating them. Candidate species are plants and animals for which the Service has sufficient information on their biological status and threats to propose them as endangered or threatened under the Endangered Species Act, but for which development of a proposed listing regulation is precluded by other higher priority listing activities.

The final environmental assessment includes lists of species that are federally or State threatened or endangered in some climate-suitable States and territories: Florida, Hawaii, Guam, Puerto Rico, and the Virgin Islands. Other States have federally or State threatened or endangered species that would be suitable prey for large constrictor snakes, including the Burmese python. These lists include only the species of the sizes and types that would be expected to be directly affected by predation by Burmese pythons and the other large constrictors. For example, plants and marine species are excluded. In Florida, 14 bird species, 15 mammals, and 2 reptiles that are threatened or endangered could be preyed upon by Burmese pythons or be outcompeted by them for prey. Hawaii has 34 bird species and 1 mammal that

are threatened or endangered that would be at risk of predation. Puerto Rico has eight bird species and eight reptile species that are threatened or endangered that would be at risk of predation. The Virgin Islands has one bird species and three reptiles that are threatened or endangered that would be at risk of predation. Guam has six bird species and two mammals that are threatened or endangered that would be at risk of predation.

Due to the wide rainfall tolerance and extensive semi-temperate native range of
P. molurus,
large areas of the southern U.S. mainland appear to have a climate suitable for survival of this species. Please refer to the Final Environmental Assessment for the climate suitability maps for each large constrictor snake species. U.S. areas climatically matched at present ranged up the east and west coasts and across the interior south from Virginia to California, and throughout most of California, Texas, Oklahoma, Arkansas, Louisiana, Mississippi, Alabama, Florida, Georgia, and South and North Carolina. In addition to the mapped areas of the United States mainland, the territories of Guam, Northern Mariana Islands, American Samoa, Virgin Islands, and Puerto Rico appear to have suitable climate. Areas of the State of Hawaii with elevations under about 2,500 m (8,202 ft) also appear to be climatically suitable. While we did not itemize the federally threatened and endangered species from California, Texas, and other States, there are likely several hundred species in those and other States that would be at risk from Burmese pythons. According to the climate suitability maps (Reed and Rodda 2009), threatened and endangered species from all of Florida, most of Hawaii, and all of Puerto Rico would be at risk from the establishment of Burmese pythons. In addition, Guam, the U.S. Virgin Islands, and other territories would have suitable habitat and climate to support Burmese pythons, and these also have federally threatened and endangered species that would be at risk if Burmese pythons became established.

The likelihood and magnitude of the effect on threatened and endangered species is high. Burmese pythons are thus highly likely to negatively affect threatened and endangered birds and mammals, as well as unlisted native species. Consistent with the language of the Lacey Act authorizing the listing of “species” and with prior administrative practice of listing only species or higher taxonomic units, we evaluated the species
Python molurus
as a whole, instead of evaluating the subspecies
Python molurus bivittatus
(Burmese python), which was the taxon originally petitioned for listing by the South Florida Water Management District. We determined that the species should be listed. As stated above under “
Native Range,”
the cold tolerance for both subspecies is similar, so the climate match (one of the evaluation criteria) determined in Reed and Rodda (2009) (also G. Rodda, pers. comm. 2009) is as applicable to each subspecies as it is to the species as a whole.

Potential Impacts to Humans

The introduction or establishment of Burmese pythons may have negative impacts on humans primarily from the loss of native wildlife biodiversity, as discussed above. These losses would affect the aesthetic, recreational, educational, and economic values currently provided by native wildlife and healthy ecosystems.

Human fatalities from nonvenomous snakes in the wild are rare, probably only a few per year worldwide (Reed and Rodda 2009). Although attacks on people by Burmese pythons are improbable, they are possible given the large size that some individual snakes can reach. However, the only human deaths in the United States from Burmese pythons that we are aware of were from captive snakes (in Colorado, Florida, Missouri, and Pennsylvania; HSUS 2010).

Ectoparasites (including ticks in the genus
Amblyomma
) were collected from wild-caught, free-ranging exotic reptiles examined in Florida from 2003 to 2008 (Corn
et al.
2011). This was the first report of collections of Neotropical ticks from wild-caught Burmese pythons,
Python molurus bivittatus.
The only known vectors capable of transmitting
Cowdria ruminantium
(which causes heartwater disease) are 13 species of ticks in the genus
Amblyomma
(Deem 1998). Heartwater disease is a devastating disease of livestock (including cattle, sheep, and goats) in Africa (Deem 1998). From limited wild-caught, free-ranging exotic reptiles in Florida (including ball and Burmese pythons), ticks and mites were native to North America, Latin America, and Africa from reptiles native to Asia, Africa, and Central and South America. These reports suggest the diversity of reptile ectoparasites introduced and established in Florida and the new host-parasite relationships that have developed among exotic and native ectoparasites and established exotic reptiles. Several studies (Burridge
et al.
2000, Kenny
et al.
2004, Reeves
et al.
2006) have shown disease agents in the ticks that travel internationally on reptiles, which may serve in the introduction of disease agents that could impact the health of local wildlife, domestic animals, and humans (Corn
et al.
2011). A potentially devastating impact to the nation's agriculture could occur if the deadly cattle disease heartwater or some other tick-borne disease were to become established in the United States and be transmissible through reptile ticks (Reed and Rodda 2009). African tick species that use pythons as hosts may be vectors of heartwater, and these ticks have been observed to transfer to other hosts, including other giant constrictors, other reptiles, and dogs. Because multiple python species are held captive together in the commercial trade, such transmission provides opportunities to occur prior to retail sales (Reed and Rodda 2009).

Factors That Reduce or Remove Injuriousness for Burmese Python

Control

No effective tools are currently available to detect and remove large constrictor populations. Traps with drift fences or barriers are the best option, but their use on a large scale is prohibitively expensive, largely because of the labor cost of baiting, checking, and maintaining the traps daily. Additionally, some areas cannot be effectively trapped due to the expanse of the area and type of terrain, the distribution of the target species, and the effects on any nontarget species (that is, they trap native wildlife as well). While the Department of the Interior, the U.S. Department of Agriculture's (USDA) Animal and Plant Health Inspection Service (APHIS), and State of Florida entities have conducted some research on control tools, there are currently no such tools available that would be adequate for eradication of an established population of large constrictor snakes, such as the Burmese python, once they have spread over a large area.

Efforts to eradicate the Burmese python in Florida have become increasingly intense as the species is reported in new locations across the State with “python catch” training sessions scheduled in locations necessary to keep the expansion to a minimum. Natural resource management agencies are expending scarce resources to devise methods to capture or otherwise control any large constrictor snake species. These agencies recognize that control of large constrictor snakes (as major predators) on lands that they manage is necessary to prevent the likely adverse impacts to

the ecosystems occupied by the invasive snakes.

The final economic analysis was prepared for the constrictor snakes (USFWS January 2012) and provides the following information about the expenditures for research and eradication in Florida, primarily for Burmese pythons, which provides some indication of the efforts to date. The Service spent about $600,000 over a 3-year period (2007 to 2009) on python trap design, deployment, and education in the Florida Keys to prevent the potential extinction of the endangered Key Largo woodrat (
Neotoma floridana smalli
) at Crocodile Lake National Wildlife Refuge. The South Florida Water Management District spent $334,000 between 2005 and 2009 and anticipates spending an additional $156,600 on research, salaries, and vehicles in the next several years. An additional $300,000 will go for the assistance of USDA, Wildlife Services (part of USDA Animal and Plant Health Inspection Service). The USDA Wildlife Research Center (Gainesville, Florida, Field Station) has spent $15,800 from 2008 to 2009 on salaries, travel, and supplies. The USGS, in conjunction with the University of Florida, has spent more than $1.5 million on research, radio telemetry, and the development, testing, and implementation of constrictor snake traps. Miami-Dade County Parks and Recreation Department, Natural Areas Management and Department of Environmental Resources Management have spent $60,875 annually on constrictor snake issues. The National Park Service has spent $317,000 annually on various programs related to constrictor snake issues in Everglades National Park. All these expenditures total $5.7 million from 2005 to approximately 2012, or roughly an average of $720,000 per year. Despite this investment, all of these efforts have failed to provide a method for eradicating large constrictor snakes in Florida.

Kraus (2009) exhaustively reviewed the literature on invasive herpetofauna. While he found a few examples of local populations of amphibians that had been successfully eradicated, he found no such examples for reptiles. He also states that, “Should an invasive [nonnative] species be allowed to spread widely, it is usually impossible—or at best very expensive—to eradicate it.” The Burmese python is unlikely to be one of those species that could be eradicated.

Eradication will almost certainly be unachievable for a species that is hard to detect and remove at low densities, which is the case with all of the four large constrictor snakes. They are well-camouflaged and stealthy, and, therefore, nearly impossible to see in the wild. Most of the protective measures available to prevent the escape of Burmese pythons are currently (and expected to remain) cost-prohibitive and labor-intensive. Even with protective measures in place, the risks of accidental escape are not likely to be eliminated. Since effective measures to prevent the establishment in new locations or eradicate, manage, or control the spread of established populations of the Burmese python are not currently available, the ability to rehabilitate or recover ecosystems disturbed by the species is low.

Potential Ecological Benefits for Introduction

While the introduction of a faunal biomass could potentially provide a food source for some native carnivores, species native to the United States are unlikely to possess the ability to hunt such large, camouflaged snakes and would not likely turn to large constrictor snakes as a food source. The risks to native wildlife greatly outweigh this unlikely benefit; however, juvenile constrictor snakes could fall prey to native wildlife such as alligators, raccoons, coyotes, and birds of prey (hawks, owls, eagles). In addition, a large constrictor snake could prey on other invasive, nonnative species, such as green iguanas, feral hogs, and black rats. However, the effect on the populations of these feral hogs, rats, and other such nonnative species is likely to be negligible. Conversely, the effect of predation on rare species is greater, because any decrease in populations of rare species makes it less likely for the population to rebound. Therefore, the small possible benefits of having large constrictor snakes as predators in the United States do not warrant encouraging their establishment.

There are no other potential ecological benefits for the introduction of Burmese pythons into the United States.

Conclusion

The Burmese python is one of the largest snakes in the world, reaching lengths of up to 7 m (23 ft) and weights of over 90 kg (almost 200 lbs). This is longer than any native, terrestrial animal in the United States, including alligators, and three times longer than the longest native snake species. Native fauna have no experience defending against this type of novel, giant predator. Hatchling Burmese pythons are about the size of average adult native snakes and can more than double in size within the first year. In addition, Burmese pythons reportedly can fertilize their own eggs and have viable eggs after several years in isolation. Even one female Burmese python that escapes captivity could produce dozens of large young at one time (average clutch size is 36, with a known clutch of 107). Furthermore, a healthy individual is likely to live for 20 to 30 years. Even a small number of pythons in a small area, such as one of the Florida Keys or insular islands, could cause unacceptable effects on federally threatened or endangered species. There are currently no effective control methods for Burmese pythons, nor are any anticipated in the near future.

Therefore, because Burmese pythons have already established populations in some areas of the United States; are likely to spread from their current established range to new natural areas in the United States; are likely to become established in disjunct areas of the United States with suitable climate and habitat if released there; are likely to prey on and compete with native species (including threatened and endangered species); are likely to be disease vectors for livestock or native wildlife; cannot be easily eradicated, prevented from establishing, or reduced from large populations or new locations; and are likely to disturb ecosystems beyond the point of recoverability, the Service finds the Burmese python and its conspecifics to be injurious to humans, agricultural interests, and to wildlife and wildlife resources of the United States.

Factors That Contribute to Injuriousness for Northern African Python

Current Nonnative Occurrences

Several Northern African pythons have been found in Florida and elsewhere in the United States—most of these are assumed to be escaped or released pets (Reed and Rodda 2009). From 2005 to 2009, adults and hatchlings have been captured, confirming the presence of a population of Northern African pythons along the western border of Miami, adjacent to the Everglades (Reed
et al.
2010). From May 2009 to January 2010, four specimens were found by herpetologists and the Miami-Dade County Anti-Venom Response Unit, including hatchlings and adults collected from an area of about 2 km (1.6 mi) in diameter known as the Bird Drive Recharge Basin (Miami-Dade County) (Reed
et al.
2010). In 2009, evidence pointed to the presence of a breeding population of Northern African pythons along the

western border of Miami adjacent to the Everglades. Recently, observations and removals of multiple adults, a gravid female, and hatchlings suggest the presence of a reproducing population of Northern African pythons (Reed
et al.
2010). One Northern African python has also been collected on State Road 72 approximately 6.43 km (4 mi) east of Myakka River State Park, Sarasota County, Florida (K. Krysko, pers. comm. 2010).

In the Commonwealth of Puerto Rico, Northern African pythons have been found in the western region of the island (Mayaguez), the San Juan metro area, and the southern region of the island (Guayama) (J. Saliva, pers. comm. 2009).

Potential Introduction and Spread

Northern African pythons have escaped captivity or been released into the wild in Florida and Puerto Rico and are likely to continue to escape and be released into the wild. Based on Reed and Rodda (2009), extrapolation of climate matching from the native range of Northern African pythons and then mapped to the United States includes a large portion of peninsular Florida, extreme south Texas, most of Hawaii, and Puerto Rico. Northern African pythons are highly likely to spread and become established in the wild due to common traits shared by the giant constrictors, including rapid growth to a large size with production of many offspring; ability to survive under a range of habitat types and conditions (habitat generalist); behaviors that allow them to escape freezing temperatures; ability to live in urban and suburban areas; ability to disperse long distances; and ability to conceal themselves and ambush prey.

Potential Impacts to Native Species (Including Threatened and Endangered Species)

Northern African pythons are highly likely to prey on native species, including threatened and endangered species. As with most of the giant constrictors, adult African pythons primarily eat endothermic prey from a wide variety of taxa. Adverse effects of Northern African pythons on selected threatened and endangered species are likely to be moderate to high.

Please see
Potential Impacts to Native Species (Including Threatened and Endangered Species)
under Factors that Contribute to the Injuriousness for Burmese Python for a description of the impacts that Northern African pythons would have on native species. These impacts are applicable to Northern African pythons by comparing their prey type with the suitable climate areas and the listed species found in those areas; suitable climate areas and the listed species can be found in the final environmental assessment.

According to the climate suitability maps (Reed and Rodda 2009), threatened and endangered species and other native species from parts of Florida, most of Hawaii, and all of Puerto Rico would be at risk from the establishment of Northern African pythons. In addition, we assume that Guam, the U.S. Virgin Islands, and other territories would have suitable habitat and climate to support Northern African pythons, and these also have federally threatened and endangered species that would be at risk if Northern African pythons became established.

Potential Impacts to Humans

The introduction or establishment of Northern African pythons may have negative impacts on humans primarily from the loss of native wildlife biodiversity, as discussed above. These losses would affect the aesthetic, recreational, and economic values currently provided by native wildlife and healthy ecosystems. Educational values would also be diminished through the loss of biodiversity and ecosystem health. African pythons (both wild and captive-bred) are noted for their bad temperament and readiness to bite if harassed by people. Although African pythons can easily kill an adult person, attacks on humans are uncommon (Reed and Rodda 2009). We do not have any confirmed human fatalities in the United States from Northern African pythons.

Diseases borne by ticks could potentially impact U.S. agricultural industries. One serious possibility is heartwater disease, a potentially catastrophic disease of hoofed animals (including cattle) that is vectored by ticks found on African pythons (such as
Python sebae
), but the ticks are capable of transferring to other species of the genus
Python
in captivity (Reed and Rodda 2009). Northern and Southern African pythons are known hosts of some of these ticks, including
Amblyomma nuttalli, Amblyomma marmoreum,

Amblyomma sparsum, Aponomma exornatum,

Aponomma flavomaculatum,
and
Aponomma latum
(Burridge 2001).

Factors That Reduce or Remove Injuriousness for Northern African Python

Control

As with the other giant constrictors, once introduced into the wild, eradication, management, or control of the spread of Northern African pythons will be highly unlikely. Please see the
Control
section for the Burmese python for reasons why the Northern African pythons would be difficult to control, all of which apply to this large constrictor.

Potential Ecological Benefits for Introduction

While the introduction of a faunal biomass could potentially provide a food source for some native carnivores, species native to the United States are unlikely to possess the hunting ability for such large, camouflaged snakes and would not likely turn to large constrictor snakes as a food source. The risks to native wildlife greatly outweigh this unlikely benefit; however, juvenile snakes could fall prey to native wildlife such as alligators, raccoons, coyotes, and birds of prey (hawks, owls, eagles). In addition, a large constrictor snake could prey on other nonnative species such as green iguanas, feral hogs, and black rats. There are no other potential ecological benefits from the introduction into the United States or establishment in the United States of Northern African pythons.

Conclusion

Northern African pythons are long-lived (some have lived in captivity for 27 years). The species feeds primarily on warm-blooded prey (mammals and birds). Northern African pythons have been found to be reproducing in Florida. Therefore, they pose a risk to native wildlife, including threatened and endangered species. African pythons (both wild and captive-bred) are noted for their bad temperament and have reportedly also attacked humans.

Because Northern African pythons are likely to escape or be released into the wild if imported to the United States; are likely to spread from their current established range to new natural areas in the United States with suitable habitats; are likely to prey on native species (including threatened and endangered species); are likely to be disease vectors for livestock; and because it would be difficult to eradicate or reduce large populations, or recover ecosystems disturbed by the species, the Service finds the Northern African python to be injurious to humans, agricultural interests, and to wildlife and wildlife resources of the United States.

Factors that Contribute to Injuriousness of the Southern African Python

Current Nonnative Occurrences

Occurrences of the Southern African python in the United States are unknown.

Potential Introduction and Spread

Southern African pythons are large-bodied constrictors that are closely related to Northern African pythons. Because they are so similar to Northern African pythons, they possess the same traits that enable them to be likely to escape or be released into the wild if imported into the United States. Southern African pythons may be substituted for Northern African pythons in the pet trade because of these similarities.

The Southern African python climate match extends slightly farther to the north in Florida than the Northern African python and also includes Texas from the Big Bend region to the southeasternmost extent of the State, as well as parts of Puerto Rico and Hawaii. If Southern African pythons escape or are intentionally released, they are likely to survive or become established within their respective thermal and precipitation limits. Within these limits, Southern African pythons are highly likely to spread and become established in the wild due to common traits shared by the giant constrictors, including rapid growth to a large size with production of many offspring; are capable of surviving under a range of habitat types and conditions (habitat generalist); have behaviors that allow them to escape freezing temperatures; can live in urban and suburban areas; can disperse long distances; and are well-concealed ambush predators.

Potential Impacts to Native Species (Including Threatened and Endangered Species)

Southern African pythons are highly likely to prey on native species, including threatened and endangered species. As with most of the giant constrictors, adult African pythons primarily eat endothermic prey from a wide variety of taxa. Adverse effects of Southern African pythons on selected threatened and endangered species are likely to be moderate to high.

Please see
Potential Impacts to Native Species (Including Threatened and Endangered Species)
under Factors that Contribute to the Injuriousness for Burmese Python for a description of the impacts that Southern African pythons would have on native species. These impacts are applicable to Southern African pythons by comparing their prey type with the suitable climate areas and the listed species found in those areas; suitable climate areas and the listed species can be found in the final environmental assessment.

According to the climate suitability maps (Reed and Rodda 2009), threatened and endangered species and other native species from parts of Florida, Texas, Hawaii, and Puerto Rico would be at risk from the establishment of Southern African pythons. In addition, we assume that Guam, the U.S. Virgin Islands, and other territories would have suitable habitat and climate to support Southern African pythons, and these also have federally threatened and endangered species that would be at risk if Southern African pythons became established.

Potential Impacts to Humans

The introduction or establishment of Southern African pythons may have negative impacts on humans primarily from the loss of native wildlife biodiversity, as discussed above. These losses would affect the aesthetic, recreational, and economic values currently provided by native wildlife and healthy ecosystems. Educational values would also be diminished through the loss of biodiversity and ecosystem health.

African pythons (both wild and captive-bred) are noted for their bad temperament and readiness to bite if harassed by people. Although African pythons can easily kill an adult person, attacks on humans are uncommon (Reed and Rodda 2009).

Diseases borne by ticks could potentially impact U.S. agricultural industry. One serious possibility is heartwater disease, a potentially catastrophic disease of hoofed animals (including cattle) that is vectored by ticks found on African pythons (such as
Python sebae
), but the ticks are capable of transferring to other species of the genus
Python
in captivity (Reed and Rodda 2009). Northern and Southern African pythons are known hosts of some of these ticks, including
Amblyomma nuttalli, Amblyomma marmoreum,

Amblyomma sparsum, Aponomma exornatum,

Aponomma flavomaculatum,
and
Aponomma latum
(Burridge 2001).

Factors That Reduce or Remove Injuriousness for Southern African Python

Control

As with the other giant constrictors, once introduced into the wild, the eradication, management, or control of the spread of Southern African pythons will be highly unlikely. Please see the
Control
section for the Burmese python for reasons why the Southern African pythons would be difficult to control, all of which apply to these large constrictors.

Potential Ecological Benefits for Introduction

While the introduction of a faunal biomass could potentially provide a food source for some native carnivores, species native to the United States are unlikely to possess the hunting ability for such large, camouflaged snakes and would not likely turn to large constrictor snakes as a food source. The risks to native wildlife greatly outweigh this unlikely benefit; however, juvenile snakes could fall prey to native wildlife such as alligators, raccoons, coyotes, and birds of prey (hawks, owls, eagles). In addition, a large constrictor snake could prey on other nonnative species such as green iguanas, feral hogs, and black rats. There are no other potential ecological benefits from the introduction into the United States or establishment in the United States of Southern African pythons.

Conclusion

Southern African pythons are long-lived. This species feeds primarily on warm-blooded prey (mammals and birds). Therefore, they pose a risk to native wildlife, including threatened and endangered species. Their climate match extends slightly farther to the north in Florida than the Northern African python and also includes portions of Texas from the Big Bend region to the southeasternmost extent of the State. Because Southern African pythons are likely to escape or be released into the wild if imported to the United States; are likely to survive, become established, and spread if escaped or released in suitable habitats; are likely to prey on and compete with native species for food and habitat (including threatened and endangered species); are likely to be disease vectors for livestock; cannot be easily eradicated, prevented from establishing, or reduced from large populations or new locations; and are likely to disturb ecosystems beyond the point of recoverability, the Service finds the Southern African python to be injurious to humans, to agricultural interests, and to the wildlife and wildlife resources of the United States.

Factors That Contribute to Injuriousness for Yellow Anaconda

Current Nonnative Occurrences

An adult yellow anaconda was collected from Big Cypress National Reserve in southern Florida in January 2007, and another individual was photographed basking along a canal about 25 km (15.5 mi) north of that location in January 2008 (EDDMapS 2011). In 2008, an unnamed observer reportedly captured two anacondas that most closely fit the description of the yellow anaconda farther to the east near the Palm Beach, Florida, county line (EDDMapS 2011). In Puerto Rico, a few individuals of the yellow anaconda have been reported in the central region of the island (Villalba area). In Arkansas, two yellow anacondas were found in Wapanocca National Wildlife Refuge (P. Fuller, pers. comm. 2011).

Potential Introduction and Spread

Yellow anacondas have escaped or been released into the wild in Florida, Arkansas, and Puerto Rico, and are likely to escape or be released into the wild elsewhere. Yellow anacondas are highly likely to survive in subtropical areas of natural ecosystems of the United States. The yellow anaconda has a native-range distribution that includes highly seasonal and fairly temperate regions in South America. When projected to the United States, the climate space occupied by yellow anaconda translates to a fairly large area, including virtually all of peninsular Florida and a corner of southeastern Georgia (to about the latitude of Brunswick), as well as parts of southern and eastern Texas and a very small portion of southern California. Large areas of Hawaii and Puerto Rico appear to exhibit suitable climates, and additional insular United States possessions (Guam, Northern Marianas, American Samoa, and so on) would probably be suitable as well. Within the areas deemed suitable, however, the yellow anaconda would be expected to occupy only habitats with permanent surface water. If yellow anacondas are released into areas with suitable permanent surface water, they would likely disperse because of their propensity for rapid growth to a large size; high reproductive rate; ability to survive under a range of habitat types and conditions (habitat generalist); behaviors that allow them to escape freezing temperatures; ability to live in urban and suburban areas; ability to disperse long distances; and well-concealed, ambush-type of predatory behavior.

Potential Impacts to Native Species (Including Threatened and Endangered Species)

Yellow anacondas are highly likely to prey on native species, including select threatened and endangered species. The prey list suggests that yellow anacondas employ both “ambush predation” and “wide-foraging” strategies (Reed and Rodda 2009). The snakes forage predominately in open, flooded habitats, in relatively shallow water; wading birds are their most common prey. They have also been known to prey on fish, turtles, small caimans, lizards, birds, eggs, small mammals, and fish carrion (Reed and Rodda). Threatened and endangered species occupying flooded areas, such as the Everglades, would be at risk.

Please see
Potential Impacts to Native Species (Including Threatened and Endangered Species)
under Factors that Contribute to the Injuriousness for Burmese Python for a description of the impacts that yellow anacondas would have on native species. These impacts are applicable to yellow anacondas by comparing their prey type with the suitable climate areas and the listed species found in those areas; suitable climate areas and the listed species can be found in the final environmental assessment.

While we did not itemize the federally threatened and endangered species from southern California, Texas, southeast Georgia, and other States, there are likely several hundred species in those and other States that would be at risk from yellow anaconda. According to the climate suitability maps (Reed and Rodda 2009), threatened and endangered species from parts of Florida, Hawaii, and Puerto Rico would be at risk from the establishment of yellow anacondas. In addition, Guam, the U.S. Virgin Islands, and other territories would have suitable habitat and climate to support yellow anacondas, and these also have federally threatened and endangered species that would be at risk if yellow anacondas became established.

Potential Impacts to Humans

The introduction or establishment of yellow anacondas may have negative impacts on humans primarily from the loss of native wildlife biodiversity, as discussed above. These losses would affect the aesthetic, recreational, and economic values currently provided by native wildlife and healthy ecosystems. Educational values would also be diminished through the loss of biodiversity and ecosystem health.

Factors That Reduce or Remove Injuriousness for Yellow Anaconda

Control

Once introduced into the wild, the eradication, management, or control of the spread of yellow anacondas will be highly unlikely. Please see the “
Control”
section for the Burmese python for reasons why yellow anacondas would be difficult to control, all of which apply to this large constrictor.

Potential Ecological Benefits for Introduction

While the introduction of a faunal biomass could potentially provide a food source for some native carnivores, species native to the United States are unlikely to possess the hunting ability for such large, camouflaged snakes and would not likely turn to large constrictor snakes as a food source. The risks to native wildlife greatly outweigh this unlikely benefit; however, juvenile snakes could fall prey to native wildlife such as alligators, raccoons, coyotes, and birds of prey (hawks, owls, eagles). In addition, a large constrictor snake could prey on other nonnative species such as green iguanas, feral hogs, and black rats. There are no other potential ecological benefits from the introduction into the United States or establishment in the United States of yellow anacondas.

Conclusion

Yellow anacondas are highly likely to survive in the appropriate natural ecosystems of the United States. The species has a native-range distribution that includes highly seasonal and fairly temperate regions in South America. When projected to the United States, the climate space occupied by yellow anaconda maps to a fairly large area, including virtually all of peninsular Florida and a corner of southeastern Georgia (to about the latitude of Brunswick), as well as large parts of southern and eastern Texas and a small portion of southern California. Large areas of Hawaii and Puerto Rico appear to exhibit suitable climates, and additional insular U.S. possessions (such as Guam, Northern Marianas, American Samoa) would probably be suitable as well. Yellow anacondas are highly likely to spread to suitable permanent surface water areas because of their large size, high reproductive potential, early maturation, rapid growth, longevity, and generalist-surprise attack predation.

Because the yellow anacondas are likely to escape captivity or be released into the wild if imported to the United

States (note that the yellow anaconda has already been found in the wild in Florida and Arkansas); are likely to survive, become established, and spread if escaped or released; are likely to prey on and compete with native species for food and habitat (including threatened and endangered species); cannot be easily eradicated, prevented from establishing, or reduced from large populations or new locations; and are likely to disturb ecosystems beyond the point of recoverability, the Service finds the yellow anaconda to be injurious to humans and to the wildlife and wildlife resources of the United States.

Conclusions for the Four Constrictor Snakes

Burmese Python

The Burmese python is one of the largest snakes in the world, reaching lengths of up to 7 m (23 ft) and weights of over 90 kilograms (kg) (almost 200 pounds (lbs)). This is longer than any native, terrestrial animal in the United States, including alligators, and three times longer than the longest native snake species. Native fauna have no experience defending against this type of novel, giant predator. Hatchling pythons are about the size of average adult native snakes and can more than double in size within the first year. In addition, Burmese pythons reportedly can fertilize their own eggs and have viable eggs after several years in isolation; therefore, it is possible that a population of Burmese pythons could be established with only a small number of females. Burmese pythons are long-lived, with a life expectancy of 20 to 30 years. Thus, even a single python (especially a female) in a small area, such as one of the Florida Keys or insular islands, can devastate the population of a federally threatened or endangered species. There are currently no effective control methods for Burmese pythons, nor are any anticipated in the near future.

Therefore, because Burmese pythons have already established populations in some areas of the United States; are likely to spread from their current established range to new natural areas in the United States; are likely to become established in disjunct areas of the United States with suitable climate and habitat if released there; are likely to prey on and compete with native species (including threatened and endangered species); are likely to be disease vectors for livestock or native wildlife; are likely to damage ecosystems that would be difficult or impossible to recover; and are difficult or impossible to eradicate or control once established, the Service finds the Burmese python to be injurious to humans, agricultural interests, and to wildlife and wildlife resources of the United States. We have evaluated the species
Python molurus
as a whole (including Burmese and Indian pythons), and we have determined that it should be listed as injurious. Moreover, we note that each of its subspecies share the traits that make this species injurious.

Northern African Python

Northern African pythons are long-lived (some have lived in captivity for 27 years). The species feeds primarily on warm-blooded prey (mammals and birds). Northern African pythons now have an established self-sustaining breeding population west of Miami, Florida. This area is within the known distribution of Burmese pythons in Florida, and hybridization between these species is known in captivity. The likelihood of hybridization among introduced Florida populations is unknown, as are the implications of genetic admixture for control purposes (Reed and Rodda 2009). Therefore, they pose a risk to native wildlife, including threatened and endangered species. African pythons (both wild and captive-bred) are noted for their bad temperament and have reportedly also attacked humans.

Because Northern African pythons are likely to escape or be released into the wild if imported to or transported within the United States; are likely to survive, become established, and spread from their current established range to new natural areas in the United States with suitable habitats; are likely to prey on and compete with native species (including threatened and endangered species); and because it would be difficult to prevent, eradicate, or reduce large populations; control the spread to new locations; or to recover ecosystems disturbed by the species, the Service finds the Northern African python to be injurious to humans and to wildlife and wildlife resources of the United States.

Southern African Python

Southern African pythons are long-lived. This species feeds primarily on warm-blooded prey (mammals and birds). Therefore, they pose a risk to native wildlife, including threatened and endangered species. Their climate match extends slightly farther to the north in Florida than the Northern African python and also includes Texas from the Big Bend region to the southeasternmost extent of the State as well as parts of Puerto Rico and Hawaii.

Because Southern African pythons are likely to escape or be released into the wild if imported to or transported within the United States; are likely to survive, become established, and spread if escaped or released in suitable habitats; are likely to prey on and compete with native species for food and habitat (including threatened and endangered species); and because it would be difficult to prevent, eradicate, or reduce large populations; control spread to new locations; or recover ecosystems disturbed by the species, the Service finds the Southern African python to be injurious to humans and to the wildlife and wildlife resources of the United States.

Yellow Anaconda

Yellow anacondas are highly likely to survive in the appropriate natural ecosystems of the United States. The species has a native-range distribution that includes highly seasonal and fairly temperate regions in South America. When projected to the United States, the climate space occupied by yellow anaconda maps to a fairly large area, including virtually all of peninsular Florida and a corner of southeastern Georgia (to about the latitude of Brunswick), as well as large parts of southern and eastern Texas. Large areas of Hawaii and Puerto Rico appear to exhibit suitable climates, and additional insular U.S. possessions (such as Guam, Northern Marianas, American Samoa) would probably be suitable as well. Yellow anacondas are highly likely to spread to suitable permanent-surface-water areas because of their large size, high reproductive potential, early maturation, rapid growth, longevity, and generalist surprise-attack predation.

Because the yellow anacondas are likely to escape captivity or be released into the wild if imported to or transported within the United States (note that the yellow anaconda has already been found in the wild in Florida); are likely to survive, become established, and spread if escaped or released; are likely to prey on and compete with native species for food and habitat (including threatened and endangered species); and because it would be difficult to prevent, eradicate, or reduce large populations; control spread to new locations; or to recover ecosystems disturbed by the species, the Service finds the yellow anaconda to be injurious to humans and to wildlife and wildlife resources of the United States.

Summary of Risk Potentials

Reed and Rodda (2009) found that all of the four constrictor snakes pose high risks to the interests of human beings,

agriculture, wildlife, and wildlife resources of the United States. These risk potentials utilize the criteria for evaluating species as described by ANSTF (1996) (see Lacey Act Evaluation Criteria above). Based on the risks determined by Reed and Rodda (2009), substantive information submitted during the public comment periods and from the peer reviewers, along with the latest findings regarding the large constrictor snakes (in Florida, Puerto Rico, and elsewhere), the Service concludes that the four constrictor species should be added to the list of injurious reptiles under the Lacey Act.

Comments Received on the Proposed Rule

During the two public comment periods for the proposed rule, we received approximately 56,500 comments, including form letters, petitions, and post cards. We received comments from Federal agencies, State agencies, local governments, commercial and trade organizations, conservation organizations, nongovernmental organizations, and private citizens; all were in English with the exception of a few in Dutch, French, German, and Italian. The comments provided a range of views on the proposed listing as follows: (1) Unequivocal support for the listing with no additional information included; (2) unequivocal support for the listing with additional information provided; (3) equivocal support for the listing with or without additional information included; (4) unequivocal opposition to the listing with no additional information included; and (5) unequivocal opposition to the listing with additional information included.

To accurately review and incorporate the publicly provided comments in our final determination, we worked with researchers in the Qualitative Data Analysis Program at the University of Massachusetts Amherst and the University of Pittsburgh—developers of the
Public Comment Analysis Toolkit (PCAT)
analytical software. The PCAT enhanced our ability to review large numbers of comments, including large numbers of similar comments on our proposed listing, allowing us to identify similar comments as well as individual ideas, data, recommendations, or suggestions on the proposed listing. We are also responding to some comments that are out of the purview of this rule in a concerted effort to explain our rationale to the public.

Peer Review of the Proposed Rule

In accordance with peer review guidance of the Office of Management and Budget “Final Information Quality Bulletin for Peer Review,” released December 16, 2004, and Service guidance, we solicited expert opinion on information contained in the proposed rule (which was for nine species) from five knowledgeable individuals selected from specialists in the relevant taxonomic group and ecologists with scientific expertise that includes familiarity with alien herpetological introductions and invasions, predictive tools for risk assessment, and invasion biology. We posted our peer review plan on the Service's Region 4 Web site (
http://www.fws.gov/southeast/informationquality
), explaining the peer review process and providing the public with an opportunity to comment on the peer review plan. No comments were received regarding the peer review plan. The Service solicited independent scientific reviewers who submitted individual comments in written form. We avoided using individuals who had already expressed strong support for or opposition to the petition and individuals who were likely to experience personal gain or loss (financial, prestige,
etc.
) as a result of the Service's decision. Department of the Interior employees were not utilized as peer reviewers.

We received responses from five peer reviewers. Two peer reviewers found that, in general, the proposed rule represented a comprehensive and up-to-date compilation of the best scientific information known about the nine constrictor snake species and conclusions drawn from both published and unpublished sources were scientifically robust, and justified the proposed rule. Two peer reviewers expressed concern with the climate-matching methods and assumptions.

In addition, all peer reviewers stated that the background material on the biology, invasive potential, and potential tools for control of each snake species represented a solid compilation of available information. They further stated that the information as presented justified the conclusion that the snake species should be listed as injurious. All five peer reviewers concluded that the data and analyses we used in the proposed rule were appropriate and the conclusions we drew were logical and reasonable. Several peer reviewers provided additional insights to clarify points in the proposed rule, or references to recently published studies that update material in the rule.

Peer Review Comments

We reviewed all comments received from peer reviewers for substantive issues and new information regarding the proposed rule. We consolidated the comments and responses into key issues in this section. We refer to them as PR (Peer Reviewer) 1 through 5. We revised the final rule to reflect peer reviewer comments, where appropriate, and the most current scientific information, including the results of the new USGS climate match publication (Rodda
et al.
2011), plus a number of new peer-reviewed journal articles. We have taken our best effort to identify the limitations and uncertainties of the climate-matching models and their projections used in the proposed rule. We have also taken our best effort to correct any grammatical or biological errors and clarify certain ambiguous statements.

Comment PR1:
In regard to the USGS publication “Giant Constrictors: Biological and Management Profiles and an Establishment Risk Assessment for Nine Large Species of Pythons, Anacondas, and the Boa Constrictor,” which includes management profiles discussing colonization potentials with climate matching maps, there are very few details or data presented in the manuscript that would allow an independent test of the model, predictions, or assumptions. At a minimum, the threshold values that were used in the climate space model should be explicitly stated for each species. This would allow reviewers to evaluate the data and the assumptions used in the construction of the model.

Response PR1:
This general critique is incorrect; all of the species-specific information used to assess risks is presented in the document mentioned. That this procedure cannot be reduced to mathematical certainty is the reason a risk assessment (rather than a calculation) was conducted. This specific critique is also incorrect. The requested threshold values are provided graphically for each of the species in Reed and Rodda (2009). For example, the
Python molurus
values are in Figure 4.3 (page 51) (heavy and dashed black lines), the
P. sebae
and
P. natalensis
values are in Figures 6.4 (page 118) and 6.5 (page 119), respectively (heavy black lines), and so forth.

For readers who want to duplicate the climate match results, the USGS has published a data series report with data used for modeling and the equations corresponding to these lines (
http://pubs.usgs.gov/ds/579/
) (Jarnevich
et al.
2011), but the graphical representations in Reed and Rodda (2009) provide the same information with the precision that is appropriate for the use of these values. Use of these values with greater precision would not be appropriate given the conceptual and scientific

uncertainties that attend state-of-the-art implementation of climate matching.

Comment PR2:
The data used for the risk assessment seems fair. This reviewer, however, was not convinced that the assignment of low, medium, and high establishment and consequence scores was sufficiently objective or transparent. There appear to be high levels of uncertainty involved in the process (pp. 253, 259: Reed and Rodda 2009). Though there is not really an alternative with the amount of data available, the approach would be more acceptable if it was transparent (what constitutes each level of certainty and how one decides on high, medium, or low for each contributing factor).

Response PR2:
The risk assessment process allows for analyzing, identifying, and estimating the dimension, characteristics, and type of risk. By applying analytical methods while acknowledging the assumptions and uncertainties involved, the process allows the assessors to utilize qualitative and quantitative data in a systematic and consistent fashion. The assessment strives for theoretical accuracy while remaining comprehensible and manageable, and the scientific and other data compiled for each snake species in the bio-profiles is organized and recorded in a formal and systematic manner. The assessment provides a reasonable estimation of the overall risk. The authors were careful to ensure that the process clearly explained the uncertainties inherent in the process and to avoid design and implementation of a process that reflected a predetermined result. Quantitative and qualitative risk assessments should always be buffered with careful professional judgment. If every statement was certain, we would not need a risk assessment. The need to balance risks with uncertainty can lead assessors to concentrate more on the uncertainty than on known facts that may affect impact potential. Risks identified for nonnative invasive large constrictor species (and other nonnative invasive species besides large constrictors) in other regions often provide the justification in applying management measures to reduce risks in regions where the species have not yet been introduced. Thus, risk assessments should concentrate on evaluating potential risk.

Uncertainty, as it relates to the individual risk assessment, can be divided into three distinct types: (a) Uncertainty of the process—(method); (b) uncertainty of the assessor(s)—(human error); and (c) uncertainty about the organism—(biological and environmental unknowns). All three types of uncertainty will continue to exist regardless of future developments. The inferential estimation of organism risk can be rated using high, medium, or low. The biological and other information assembled under each element will drive the process. This forces the assessor to use the biological information as the basis for his or her decision. Thus, the process remains transparent for peer review. The high, medium, and low ratings of the individual elements contributing to the probability of organism establishment (such as organism with pathway, entry potential, colonization potential, and spread potential) cannot be defined or measured—they have to remain judgmental. This is because the values of the elements contained under “Probability of Establishment” are not independent of the rating of the “Consequences of Establishment.” Specific traits or biological characteristics were assessed for each snake species to arrive at each high, medium, or low rating. The strength of the analysis is not in the element-rating but in the detailed biological and other relevant information that supports them. Reed and Rodda (2009) followed the ANSTF 1996 (see Lacey Act Evaluation Criteria section above for explanation of this method) guidelines for combining scores and noting that certainty levels for each component of the process were followed by the risk assessors. The logic that was applied to develop every step of the risk assessment analysis can be found in Chapter Ten of Reed and Rodda (2009).

Comment PR3:
Jacobs
et al.
(2009) elevated the Burmese python back to full species rank (that is, the form was historically described as
Python bivittatus,
then lumped with
P. molurus,
and then upon recent reevaluation, elevated back to full species rank). Climate data for
P. molurus
should, therefore, not have been used to project the area potentially suitable for
P. bivittatus,
a different species.

Response PR3:
Jacobs
et al.
(2009) presented one side of an argument that has been debated for almost 100 years; they argued for full species status, but did not have the authority to declare their preference to be

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2012-1155. Public record. Not legal advice.