E6-15874. Endangered and Threatened Wildlife and Plants; 90-Day Finding on a Petition To List the Anacapa Deer Mouse as Threatened or Endangered

AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Notice of 90-day petition finding.

SUMMARY:

We, the U.S. Fish and Wildlife Service (Service), announce a 90-day finding on a petition to list the Anacapa deer mouse (Peromyscus maniculatus anacapae) as threatened or endangered under the Endangered Species Act of 1973, as amended. We find the petition does not present substantial information indicating that listing the Anacapa deer mouse may be warranted. Therefore, we are not initiating a status review in response to this petition. We ask the public to submit to us any new information that becomes available concerning the status of the subspecies or threats to it or its habitat at any time. This information will help us monitor and encourage the conservation of the subspecies.

DATES:

The finding announced in this document was made on September 28, 2006.

ADDRESSES:

The complete supporting file for this finding is available for public inspection, by appointment, during normal business hours at the Ventura Fish and Wildlife Office, U.S. Fish and Wildlife Service, 2493 Portola Road, Suite B, Ventura, California 93003. Submit new information, materials, comments, or questions concerning this subspecies to us at the above address.

FOR FURTHER INFORMATION CONTACT:

Diane Noda, Field Supervisor, Ventura Fish and Wildlife Office (see ADDRESSES section above), by telephone at 805/644-1766, or by facsimile at 805/644-3958.

SUPPLEMENTARY INFORMATION:

Background

Section 4(b)(3)(A) of the Endangered Species Act of 1973, as amended (Act) (16 U.S.C. 1531 et seq.), requires that we make a finding on whether a petition to list, delist, or reclassify a species presents substantial scientific or commercial information to indicate that the petitioned action may be warranted. We are to base this finding on information provided in the petition, supporting information submitted with the petition, and information otherwise available in our files at the time we make the determination. To the maximum extent practicable, we are to make this finding within 90 days of our receipt of the petition, and publish our notice of this finding promptly in the Federal Register.

Our standard for substantial information within the Code of Federal Regulations (CFR) with regard to a 90-day petition finding is “that amount of information that would lead a reasonable person to believe that the measure proposed in the petition may be warranted” (50 CFR 424.14(b)). If we find that substantial information was presented, we are required to promptly commence a review of the status of the species.

In making this finding, we relied on information provided by the petitioners and evaluated that information in accordance with 50 CFR 424.14(b). Our process of coming to a 90-day finding under section 4(b)(3)(A) of the Act and section 424.14(b) of our regulations is limited to a determination of whether the information in the petition meets the “substantial information” threshold.

On November 8, 2002, we received a formal petition, dated October 29, 2002, from the Channel Islands Animal Protection Association and The Fund for Animals. The petition requested that the Anacapa deer mouse (Peromyscus maniculatus anacapae) be emergency listed as threatened or endangered in accordance with section 4 of the Act. The petition clearly identified itself as such and contained the names, addresses, and signatures of the petitioning organizations' representatives. In response to the petitioner's requests, we sent a letter to the petitioners dated March 10, 2003, explaining that we would not be able to address their petition until fiscal year 2004. The reason for this delay was that responding to existing court orders and settlement agreements for other listing actions required nearly all of our listing funding. We also concluded in our March 10, 2003, letter that emergency listing of the Anacapa deer mouse was not indicated. Delays in responding to the petition continued due to the high priority of responding to court orders and settlement agreements, until funding recently became available to respond to this petition.

Subspecies Information

The deer mouse (Peromyscus maniculatus) is an abundant member of the rodent family Muridae and is widespread throughout much of North America except for the southeastern United States and some parts of Mexico. Adults range in size from 119 to 222 millimeters (5 to 9 inches) and weigh from 10 to 24 grams (0.4 to 0.8 ounces). Deer mice range from grayish to reddish-brown with white underparts, and the tail is covered with fine hairs and is sharply bicolored (dark above, white below) (Bunker 2001, pp. 1-6).

Deer mice may breed year-round, but breeding is more frequent during the warmer months when they may produce a litter every 3 to 4 weeks. Gestation ranges from 22 to 31 days depending on whether or not the female is lactating; typical litter size is 4 to 6. Deer mice are primarily nocturnal and have keen senses of vision, hearing, touch, and smell. Nests may be located in trees, stumps, wood piles, or buildings and may be constructed of leaves, grasses, shredded bark, moss, paper, cloth, or any other available material. The home ranges of deer mice vary from 242 to 3,000 square meters (0.06 to 0.74 acres (ac)). Home ranges of males are larger than females and show more overlap. Females defend their territories more than males; therefore their territories overlap less. Deer mice are omnivorous and eat a wide variety of plant and animal material including seeds, fruit, flowers, nuts, insects, and other invertebrates. Deer mice are themselves preyed upon by a variety of predators, including snakes, birds of prey, and mammalian predators.

Deer mice are found on all eight of the Channel Islands (from north to south: San Miguel, Santa Rosa, Santa Cruz, Anacapa, Santa Barbara, San Nicolas, Santa Catalina, and San Clemente), and are classified as separate subspecies on each island (Pergams and Ashley 2000, p. 278). Deer mice on the Channel Islands are generally darker and somewhat larger than those on the mainland, with the Anacapa deer mouse being one of the larger of the Channel Island deer mice (Pergams and Ashley 2000, p. 279). Channel Island deer mice have been variously described since 1897 (Mearns 1897, pp. 719-724), when they were first identified; however, von Bloeker (1940, pp. 172-174; 1941, pp. 161-162) first described those from Anacapa Island as a separate subspecies. As indicated by its name, the Anacapa deer mouse is the endemic subspecies to Anacapa Island.

Anacapa Island is one of the five islands that comprise the Channel Islands National Park and is the closest to the mainland, approximately 15 kilometers (km) (9 miles (mi)) from the nearest point along the coast. Anacapa Island is approximately 8 km (5 mi) long and is comprised of three islets, East Anacapa, Middle Anacapa, and West Anacapa. Anacapa deer mice are known to occur on all three of the islets. The three islets are in close proximity to each other (less than 150 meters (450 feet)), and the total area of the three islets combined is approximately 290 hectares (717 ac). The rugged terrain of the island is characterized by steep cliffs and canyons, which provide limited access to the island. Access is also limited by National Park Service (NPS) regulations and during the nesting season of the endangered brown pelican (Pelicanus occidentalis). Vegetation on the island consists of mainly grasslands and scrub vegetation and is heavily influenced by nonnative species, including several nonnative grasses and iceplant (Malephora crocea).

Although minor genetic differences occur between the deer mice on the three islets, all of them are classified as the same subspecies (Peromyscus maniculatus anacapae) based on both similar genetic and morphological characteristics (Pergams and Ashley 2000, p. 286). Pergams and Ashley (2000, p. 286) concluded that genetic similarities between the deer mice on the three islets indicates some migration between the islets occurs on a regular basis. As noted by Pergams and Ashley (2000, p. 286), deer mice were thought to be very rare on East Anacapa since 1966, and possibly extinct since about 1981; they were again found on East Anacapa in 1997. The genetic research of Pergams and Ashley (2000, p. 286) suggests either that the deer mice on East Anacapa were never completely extirpated or that East Anacapa was recolonized from one of the other islets.

Although not listed as either threatened or endangered by the State of California, the California Department of Fish and Game (CDFG) has listed the Anacapa deer mouse as a Species of Special Concern.

Threats Analysis

Section 4 of the Act and its implementing regulations (50 CFR part 424) set forth the procedures for adding species to the Federal List of Endangered and Threatened Wildlife and Plants. A species may be determined to be an endangered or threatened species due to one or more of the five factors described in section 4(a)(1) of the Act: (A) Present or threatened destruction, modification, or curtailment of habitat or range; (B) overutilization for commercial, recreational, scientific, or educational purposes; (C) disease or predation; (D) inadequacy of existing regulatory mechanisms; or (E) other natural or manmade factors affecting its continued existence. In making this finding, we evaluated whether threats to the Anacapa deer mouse presented in the petition and other information available in our files at the time of the petition review may pose a concern with respect to the subspecies' survival. Our evaluation of these threats is presented below. The petition did not address the five listing factors directly and did not organize potential threats to the Anacapa deer mouse by listing factor. In the discussion below, we have placed the threats listed in the petition under the most appropriate listing factor.

A. The Present or Threatened Destruction, Modification, or Curtailment of Its Habitat or Range

The petition did not list any threats to the habitat of the Anacapa deer mouse. We are not aware of any scientific or commercial information to indicate there are any present or future threats to the habitat of the Anacapa deer mouse.

B. Overutilization for Commercial, Recreational, Scientific, or Educational Purposes

The petition did not provide information or list any threats to the Anacapa deer mouse from overutilization for commercial, recreational, scientific, or educational purposes. We are not aware of any scientific or commercial information that would indicate there are any past, present, or future threats to the Anacapa deer mouse from overutilization for commercial, recreational, scientific, or educational purposes.

C. Disease and Predation

The petition did not list any threats to the Anacapa deer mouse from disease or predation. We are not aware of any scientific or commercial information that would indicate disease or predation poses a current threat to the Anacapa deer mouse. However, prior to the black rat (Rattus rattus) eradication program on Anacapa Island, information from the NPS (2003, p. 1) indicated that one of the most serious threats to the Anacapa deer mouse was the presence of the introduced black rat on the island. Black rats were likely first introduced to the island as a result of shipwrecks (NPS 2006, p. 1). Black rats are known to prey on Anacapa deer mice, and also compete with them for food and exclude them from certain habitats (NPS 2003, p. 1). Black rats may also have been responsible for the disappearance of deer mice on East Anacapa from at least 1981, until they were again found in 1997 (Pergrams and Ashley 2000, p. 286; NPS 2003, p. 1). As of post-eradication monitoring in 2005, black rats are no longer found on Anacapa Island (Howald et al. 2005, p. 305). Therefore, black rats are not a threat to the Anacapa deer mouse at the present time.

D. The Inadequacy of Existing Regulatory Mechanisms

Information Provided in the Petition

The petitioners were concerned that the NPS project to eradicate black rats from Anacapa Island with poison would result in the extinction of the Anacapa deer mouse, and that the NPS mitigation plan for the mouse was insufficient. Specifically, the petition states that, “The NPS project poisoning Anacapa Island represents the premeditated man-made destruction of a large percentage of an already jeopardized population. This demonstrates that the listing by California Fish and Game [as a Species of Special Concern] insufficiently protects the rare Anacapa Deer Mouse, and that Federal listing under the Endangered Species Act is necessary.”

Analysis of Information Provided in the Petition and Information Available to Us at the Time of Petition Review

The CDFG Species of Special Concern designation does not result in additional regulatory requirements with regard to Federal activities such as the NPS's black rat eradication activities, but is intended to result in special consideration for these animals by CDFG, land managers, consulting biologists, and others, and focus attention on the species to avert the need for listing under Federal and State endangered species laws. For example, the CDFG was one of the parties involved in formulating the basic plan for eradicating black rats from Anacapa Island and approving the funding for the Anacapa Island black rat eradication program (American Trader Trustee Council 2001, pp. 20-23). As a participant, the CDFG recognized both that the black rat was a threat to the Anacapa deer mouse (American Trader Trustee Council 2001, p. 21) and that eradicating black rats was likely to have a positive benefit to the Anacapa deer mouse in the long term (American Trader Trustee Council 2001, p. 22). However, it was also recognized that the poisoning of the rats would also poison other species, including the Anacapa deer mouse, but that the overall benefit to the island ecology would outweigh the short-term effects (American Trader Trustee Council 2001, p. 22). The importance of the Anacapa deer mouse was further recognized in that the NPS developed (NPS 2000, p. 17) and successfully carried out (Howald et al. 2005, p. 305) a plan for ensuring the protection of the mouse (for details see E. Other Natural or Manmade Factors Affecting Continued Existence below). Therefore, the status of the Anacapa deer mouse as a California Species of Special Concern played an important role in ensuring the protection of this subspecies during the planning stages of the black rat eradication process. We also note that the petition was prepared prior to the final black rat eradication activities that were completed in November 2002.

Several Federal laws pertaining to national parks act indirectly protect the Anacapa deer mouse as one of many sensitive park resources. As noted above, Anacapa Island is part of the Channel Islands National Park (CINP). CINP was established in 1980, by Public Law (Pub. L.) 96-199, “* * * to protect the nationally significant natural, scenic, wildlife, marine, ecological, archaeological, cultural, and scientific values of the Channel Islands in the State of California.” CINP is also affected by other laws pertaining to national parks. The NPS Organic Act of 1916 (16 U.S.C. 1) established the National Park Service and mandated that it “shall promote and regulate the use of the Federal areas known as national parks, monuments, and reservations * * * by such means and measures as conform to the fundamental purpose of the said parks, monuments, and reservations, which purpose is to conserve the scenery and the natural and historic objects and the wild life therein and to provide for the enjoyment of the same in such manner and by such means as will leave them unimpaired for the enjoyment of future generations.” Redwood National Park Expansion Act (Pub. L. 95-250) of 1978 directs that within the National Park System, “authorization of activities shall be construed and the protection, management, administration of these areas shall be conducted in light of the high public value and integrity of the National Park System and shall not be exercised in derogation of the values and purposes for which these various areas have been established.” National Parks Omnibus Management Act of 1998 (Pub. L. 105-391) directs “the National Park Service to provide state-of-the-art management, protection, and interpretation of and research on the resources of the National Park system.” This law also stipulates that “the trend in the condition of resources of the National Park System shall be a significant factor in the annual performance evaluation of each superintendent of a unit of the National Park System.”

The National Environmental Policy Act of 1969 (42 U.S.C. 4321 et seq.), as amended (NEPA), requires all Federal agencies to formally document and publicly disclose the environmental impacts of their actions and management decisions. NEPA documentation is provided in either an environmental impact statement (EIS), an environmental assessment, or a categorical exclusion, and may be subject to administrative or judicial appeal. The NPS considered the impacts of black rat eradication on the Anacapa deer mouse in their EIS on the Anacapa Island Restoration Project (NPS 2000, p. 1-139) and included a mitigation plan for the Anacapa deer mouse (NPS 2000, p. 17).

Therefore, the State and Federal regulations listed above acted to ensure that the future of the Anacapa deer mouse was considered and planned for during the black rat eradication project, and we find that the petition, supporting information, and information readily available to the Service does not present substantial information for this factor indicating that the petitioned action may be warranted.

E. Other Natural or Manmade Factors Affecting Continued Existence

Information Provided in the Petition

One of the concerns raised in the petition is the fact that the Anacapa deer mouse is restricted to a single island and therefore is vulnerable to extinction. However, the principal threat to the Anacapa deer mouse presented in the petition was the detrimental effects on the Anacapa deer mouse from the NPS project to eradicate black rats from the island. The eradication of black rats on Anacapa Island, which was initiated in 2001 as part of the Anacapa Island Restoration Project (NPS 2000, pp. 1-139), involved the aerial application of bait poisoned with the rodenticide brodifacoum. The petition stated that the application of brodifacoum to kill black rats would also kill all of the Anacapa deer mice on the island that had not been brought into captivity. Furthermore, the petitioners concluded that the NPS plan for ensuring the survival of the Anacapa deer mouse was insufficient to guarantee success. The petitioners believed that either the NPS would not capture enough mice to ensure that there would be a sufficient number available to repopulate the island or the mouse population would likely undergo a drastic crash while in captivity, which would again result in too few to repopulate the island. The petitioners stated that, although the geneticist for the NPS recommended 333 deer mice be captured on each of the three islets, the NPS only captured 175 on East Anacapa. The petitioners believed a crash in the captive population was likely to result from either the physical and psychological stresses of capture and confinement or from a rogue pathogen that would rapidly spread throughout the captive population or from a combination of these two reasons. Another issue the petitioners raised was the possibility that holding Anacapa deer mice in captivity could induce a genetic change that would alter the evolutionary process of the Anacapa deer mouse and that such a change could occur within just a few reproductive cycles. The petitioners believed that a genetic change in the captive Anacapa deer mice could result from the stress of captivity, limited breeding selection, radical environmental changes, or an unknown influence. They also believed that this genetic change could be detrimental to the survival of the Anacapa deer mice once they were released back to Anacapa Island. The petitioners also stated that the captive Anacapa deer mice must be released at a specific point in their population cycle to maximize chances of survival. Finally, the petitioners believed that the poison bait could remain in the environment for decades and threaten any Anacapa deer mice released.

Analysis of Information Provided in the Petition and Information Available to Us at the Time of Petition Review

We agree with the petitioners that species, such as the Anacapa deer mouse, that inhabit islands, especially small islands, are vulnerable to extinction. However, over the last several hundred years, most island extinctions have resulted from human-related threats, especially introduced species such as the black rat (for a review of island extinctions, see Chapter 20 in Bryant 2005, pp. 1-19). We do not base a decision to list a species as endangered or threatened because it is restricted to an island or is simply rare, but because its existence is threatened by one or more of the five listing factors. Recognizing the damage black rats were doing to nesting seabirds and the environment of Anacapa Island, the NPS developed and carried out a project to eliminate rats from the island as part of their goal to restore the ecology of the island (NPS 2000, pp. 1-139). Predation by black rats was probably the main cause for the long-term decline in the breeding populations of Xantus's murrelets (Synthliboramphus hypoleucus) and other seabirds observed on Anacapa Island (McChesney et al. 2000, p. 2). The NPS stated that maintaining the island as rat-free would improve seabird nesting habitat and aid in the recovery of crevice-nesting seabirds, such as the Xantus's murrelet and ashy storm-petrel (Oceanodroma homochra). The abundance of crevice-nesting habitat at Anacapa Island suggests a potential for Anacapa Island to support large populations of these species (NPS 2000, p. 6). The removal of black rats from Anacapa Island would provide a substantial increase in nesting habitat available to these seabird species in California (NPS 2000, p. 6). The removal of black rats would also benefit the Anacapa deer mouse in the long term. Rats may have been the cause of extirpation of deer mice from East Anacapa; deer mice were rediscovered there in 1997. If not eliminated, the black rats could lead to the extirpation of deer mice again, which could have serious implications for the birds of prey that rely on the deer mice as their primary prey base (NPS 2000, p. 53).

We concur with the petitioners that the use of poison bait to kill black rats would also kill Anacapa deer mice. This was also recognized by the NPS (2000, pp. 1-139), and during implementation of the black rat eradication program, the remaining free-ranging Anacapa deer mice were killed (Howald et. al. 2005, p. 305). To prevent the extermination of the Anacapa deer mouse along with the black rats, the NPS developed and followed a mitigation plan for the Anacapa deer mouse (NPS 2000, pp. 1-139; Howald et. al. 2005, p. 302). The mitigation plan included conducting the black rat poisoning over a 2-year period, which allowed for staggering of the poisoning between East Anacapa and the other islets so that there would be free-ranging mice at all times on at least one of the islets. The mitigation plan also called for using bait that would degrade rapidly, capturing sufficient Anacapa deer mice to ensure success, releasing mice back to each islet at the appropriate time, providing supplemental food to the newly released mice, and monitoring mouse populations over time (NPS 2000, pp. 17-18). The black rat eradication program began with the application of poisoned bait on East Anacapa in December 2001, followed by the release of the Anacapa deer mice held in captivity onto East Anacapa in spring 2002 (NPS 2003, p. 1), and the poisoning of rats on Middle and West Anacapa in November 2002 (Howald et. al. 2005, p. 301). Finally, Anacapa deer mice were released on Middle and West Anacapa in spring 2003 (NPS 2003, p. 1). Subsequent monitoring has shown that the eradication program successfully eliminated all black rats from the island (Howald et. al. 2005, p. 305).

Prior to the application of poison to the island, genetic research indicated that deer mice from the three Anacapa islets were all the same subspecies (Pergrams et al. 2000, p. 828). A population viability analysis was conducted on the Anacapa deer mouse that indicated a total of 1,000 mice would be required to successfully repopulate the island and maintain genetic diversity (Pergrams et al. 2000, p. 829). However, to ensure that the Anacapa deer mouse subspecies was protected and that healthy deer mouse populations could be restored to Anacapa Island (NPS 2003, p. 1), the NPS captured and released over 1,700 Anacapa deer mice (Howald et. al. 2005, p. 302). To further ensure the survival of the Anacapa deer mice released back to the island, the bait used for poisoning the rats was selected because it would break down in a matter of days (Howald et. al. 2005, p. 303), thereby eliminating the concern that captive Anacapa deer mice would be poisoned after being released back to the island. Many of the Anacapa deer mice were released in the early spring, which was considered the optimum time because it was the start of the breeding season and a time when natural food would be most abundant. Subsequent monitoring of the released population using marking and recapture techniques showed that the mice were reproducing in the wild and increasing in numbers (Faulkner 2003). By May 2003, the population of Anacapa deer mice on East Anacapa had increased to over 8,000 individuals (NPS 2003, p. 1). By August 2003, the estimated number of Anacapa deer mice had increased to at least 16,000 on East Anacapa and 2,600 on Middle Anacapa (Faulkner 2003). Finally, the NPS concluded monitoring Anacapa deer mouse populations in Fall 2004, when the population was about 13,500 on East Anacapa, 23,400 on Middle Anacapa, and 42,500 on West Anacapa for a combined total of over 79,000 mice (Gellerman 2005). The NPS did not conduct any type of genetic research on deer mice either while they were being held in captivity or after their release. Therefore, we cannot specifically address the possibility that genetic changes may have occurred in the captive deer mice. However, based on the rapid increase in numbers that occurred in the released deer mice, it is unlikely that any significant genetic change occurred during their captivity or if a change did occur, it was not detrimental to their recovery.

As a result, we find that the petition, supporting information, and information readily available to the Service does not present substantial information for this factor indicating that the petitioned action may be warranted.

Finding

We evaluated each of the five listing factors individually, and because the threats to the Anacapa deer mouse are not mutually exclusive, we also evaluated the collective effect of these threats. The petitioners raised a concern about the fact that the Anacapa deer mouse is restricted to a single island and therefore is vulnerable to extinction, but were primarily concerned that the NPS project to eradicate black rats from Anacapa Island with poison would result in the extinction of the Anacapa deer mouse, and that the NPS mitigation plan for the mouse was insufficient. When the petitioners submitted their petition in October 2002, the NPS had not yet completed either the process of eradicating black rats from the island or repopulating the island with captive Anacapa deer mice. Now that the project is completed, we know that the NPS was successful not only in eradicating black rats from the island but also protecting enough Anacapa deer mice to recover the population on the island. We conclude that the petitioners' concerns regarding the Anacapa deer mouse mitigation plan, including the likelihood of an insufficient number of captive mice to be successful, population crashes while in captivity, detrimental genetic change, timing of release, and longevity of poisoned bait, are no longer threats to the Anacapa deer mouse. We are unaware of any threats to the Anacapa deer mouse that would indicate that the long-term viability of the subspecies is a concern and that the subspecies is either in danger of extinction throughout all or a significant portion of its range or likely to become an endangered species. Therefore, we find the petition, supporting information, and information readily available to the Service does not present substantial information indicating that the petitioned action may be warranted.

We have reviewed the petition and literature cited in the petition and evaluated that information in relation to information available to us. After this review and evaluation, we find the petition does not present substantial scientific information to indicate listing the Anacapa deer mouse may be warranted at this time. Although we will not commence a status review in response to this petition, we will continue to monitor the subspecies' population status and trends, potential threats, and ongoing management actions that might be important with regard to the conservation of the Anacapa deer mouse across its range. We encourage interested parties to continue to gather data that will assist with the conservation of the subspecies. If you wish to provide information regarding the Anacapa deer mouse, you may submit your information or materials to the Field Supervisor, Ventura Fish and Wildlife Office (see ADDRESSES section).

References Cited

A complete list of all references cited herein is available, upon request, from the Ventura Fish and Wildlife Office (see ADDRESSES section).

Author

The primary author of this notice is the staff of the Ventura Fish and Wildlife Office (see ADDRESSES section).

Authority

The authority for this action is section 4 of the Endangered Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).

Dated: September 20, 2006.

Marshall P. Jones,

Acting Director, Fish and Wildlife Service.