The Mexican Wolf

Rachel E. Wells / Wolf Song of Alaska Volunteer

A. Natural History

The Mexican wolf is the rarest and most genetically distinct subspecies of the gray wolf in North America (Department of Interior 1997). Natural history information on the Mexican wolf is fragmented because most of the wolves in the wild disappeared before any research was conducted. Most of the information comes from trapper journals and reports. Mexican wolves typically weigh 70 to 90 lbs., average 4.5 to 5.5 feet from nose to tail, and stand 28 to 32 inches at the shoulder. They breed in late January through early March, and give birth to an average of 4 to 6 pups about 63 days later. They prefer mountain woodlands to desert, because of the combination of cover, water, and available prey (deer, elk, javelina, rabbits, and small mammals). Since their prey is relatively small and less individuals are needed to take down smaller prey, pack sizes were probably smaller than their northern gray cousins. Packs usually consist of 5 to 6 individuals. The formation of the pack is based on the breeding pair and their recent offspring living in a territory of several hundred square miles.

The Mexican wolf was listed as an endangered species in 1976 and is now considered extinct in the wild in the United States. Mexican wolves once roamed the mountains of the southwest from Mexico City to southern Arizona, New Mexico, and Texas (see map B in Appendix). They inhabited areas such as the Sierra Madre Occidental (six hundred miles long), the mountains of western Coahuila and eastern Chihuahua, and western San Luis Potosi (Cahalane 1964, in Mech 1970). The last documented killings of Mexican wolves in the U.S. were in 1970 in Texas and New Mexico (Department of Interior 1997). A few may remain in the wild in Mexico but their presence has not been confirmed since 1980 (USFWS 1995). The last verified sighting of a Mexican wolf in the wild was in 1980 in Chihuahua, Mexico (Department of Interior 1997). Occasional sighting reports are received from the U.S./ Mexico border around Arizona, New Mexico, and Texas but no reports have been verified (USFWS 1995). Currently, the taking of wolves is prohibited in all Mexican states except Sonora and Chihuahua. Aggressive predator control, loss of habitat, and a decrease in prey numbers led to the Mexican wolf decline beginning in 1915. By the 1930's, Mexican wolves were believed to be extinct in the wild.

B. Recovery Efforts

Mexican wolves are considered the most endangered subspecies of gray wolf in the world. In 1993, only 50 survived in captive breeding programs (P.A.WS January, 1993). At this time numbers were so low that hope for increasing numbers in the wild was slim. The recovery effort focused on a captive breeding program to maintain and increase numbers for eventual reintroduction into former habitat. A captive population of 100 individuals was to be established before any reintroductions would occur.

Under an agreement between the U.S. and Mexico, four males and one pregnant female were captured between 1977 and 1980 in Durango and Chihuahua, Mexico (USFWS 1995). They were transferred to the U.S. to establish a certified breeding program which is managed by the FWS under the American Zoo and Aquarium Association's "Species Survival Plan Program"(USFWS 1995). A Mexican Wolf Recovery Team was established by the FWS in August 1979. In 1982, the team developed a plan that was approved by the U.S. and Mexico (P.A.WS. January, 1993). The goal of the plan was, "To conserve and ensure the survival of Canis lupus baileyi by maintaining a captive breeding program and re-establishing a viable, self sustaining population of at least 100 Mexican wolves in the middle to high elevations of a 5,000 square-mile area within the Mexican wolf's historic range" (USFWS 1995).

Since 1978, 194 certified Mexican wolf pups have been born in captivity (USFWS 1995). As of June 1995, there were 91 Mexican wolves at 19 cooperating facilities in the U.S. and 13 at 5 facilities in Mexico (USFWS 1995). In July, 1995, 2 additional lineages from unofficial breeding programs of captive Mexican wolves were included under the recovery plan (USFWS 1995). Both these unofficial captive programs had been operating since the 1960's (the Ghost Ranch population in the U.S. and the Aragon population in Mexico) but the origin of these individuals was uncertain. Molecular genetic analyses helped to identify that these populations were pure Mexican wolves. These two lineages brought 4 new breeding adults and 33 individuals to the USFWS breeding program which brought the total captive population to 137 (USFWS 1995).

Soon after the Recovery Team was formed, a "Memorandum of Understanding" was signed by the U.S. Fish and Wildlife Service and Arizona Game and Fish Department. They wanted to establish a framework for cooperation and participation in order to promote recovery of the Mexican wolf. The primary objectives were: (1) establish and support a long term project to reestablish captive reared Mexican wolves in eastern-central Arizona and in areas in New Mexico, (2) achieve goals established in the Mexican Wolf Recovery Plan, and (3) provide for enhanced awareness and involvement of other agencies, local and tribal governments, communities, and citizens (P.A.WS., August 5, 1997).

One of the first steps in the Mexican Wolf Recovery Plan was to conduct extensive feasibility surveys of possible reintroduction sites. Each site would be extensively analyzed to, "determine biological and ecological features of each candidate area: size, topography, and other geological features; climate; availability of surface water; vegetative make-up; estimated numbers and distribution of wild prey species, especially endangered prey species; livestock use of area, including kinds and numbers of livestock, seasonal patterns of use, and evaluation of impact of existing livestock use on habitat and on wild ungulates and any other species of possible importance to wolves as prey; presence of any natural or artificial perimeter obstacles to wolf emigration..." (P.A.WS August 10,1995). In addition, the team was required to, "determine economic and sociological values of existing human use of each candidate area: economic value of existing and other agricultural use; existing predator control methods in and near area; nature of economic value of hunting and other recreational uses of area; extents and values of other human uses of area" (P.A. WS August 10, 1995).

The two principal areas that were determined suitable for reintroduction were the White Sands Missile Range in New Mexico and the Blue Range area of Arizona. The White Sands Wolf Recovery Area (WSWRA) is about 4,000 square miles which includes additional surrounding land owned by the Bureau of Land Management (USFWS 1995). The Blue Range Wolf Recovery Area (BRWRA) is about 7,000 square miles which includes all of the land of the Apache and Gila National Forests in Arizona and New Mexico. The Arizona Game and Fish Commission voted that the Mexican wolf reintroduction should occur in White Sands Missile Range, based on an "experimental, nonessential" designation of the wolves and an adaptive management plan that would determine if subsequent reintroductions should occur. New Mexico did not approve of the Blue Range Area as a site but if the reintroduction into WSWRA was successful then New Mexico stated it would consider the Blue Range area. The New Mexico Department of Fish and Game opposed the reintroduction into White Sands, due to lack of livestock. They felt that the reintroduction should be an excellent opportunity to continue research in livestock depredation, which would not be possible in White Sands. Both the USFWS and Arizona Game and Fish Department emphasized that the Blue Range area is the best site, biologically for Mexican Wolves (P.A.WS November 15, 1995). There is a great amount of prey diversity and the area is a large, remote, rugged, and forested wilderness. The White Sands area is more suited to an initial experimental release which requires extensive monitoring (P.A.WS November 15, 1995). This area is smaller, less rugged, and has no prominent livestock industry which would greatly reduce any potential conflicts with depredation. Map C in the Appendix shows the White Sands Wolf Recovery Area and Blue Range Wolf Recovery Area with the primary and secondary recovery zones designated in each area. Primary recovery zones are where wolves will be released. Secondary recovery zones are areas where reintroduced wolves are allowed to disperse (FWS 1995).

Various management plans were examined by the USFWS. One type of management suggested was the creation of "wolf management areas" which could reduce threats to livestock. These areas consist of a core area which has low levels of livestock grazing, but is large enough to support a small, viable population of wolves (P.A.WS August 10, 1995). Individual wolves would be managed and completely protected in this area. Outside of the core area is a buffer zone where wolves would be tolerated but could be recaptured and relocated if problems arose (P.A.WS August 10, 1995). Bordering the buffer zone, would be a third area that has established human land use activities (P.A.WS August 10, 1995). Conflicts would be resolved according to the type of land use. Livestock depredation would call for removal of the wolf.

In the creation of the Environmental Impact Statement (EIS), the USFWS considered four alternative reintroduction techniques and regulations. These four alternatives were (Wolf! No. 2, 1994):

A: Nonessential, experimental releases allowing dispersal into secondary recovery zones.

B: No releases; research and support would be provided for natural recolonization. Mexican wolf status would remain as endangered. Natural recolonization would be supported in southeast Arizona, southwest New Mexico, and Big Bend National Park in Texas.

C: Nonessential, experimental releases preventing dispersal into secondary areas, WSWRA and BRWRA would be primary zones. Wolves caught dispersing into secondary areas would be re-captured and either placed in captivity or back into primary recovery zones.

D: Release under full protection of the ESA into same areas as A, plus likely dispersal areas.

The highest cost (in 1993 dollars) would be for Alternative B which is expected to cost over $8 million. Alternative C would have the lowest cost, just over $2 million (Wolf! No.2, 1994).

The reintroduction has had opposition from ranchers and politicians. Overall support has been strong in the general public. Public hearings were conducted to address concerns in New Mexico, Arizona, and Texas. The Arizona Department of Fish and Game came out in favor of the reintroduction with Alternative A, as long as the initial wolves were placed in the White Sands area of New Mexico (Wolf! Fall1995/Winter 1996). Texas Parks and Wildlife opposed the plan, even though no reintroduction was scheduled to occur in Texas. Big Bend National Park was initially considered but was later turned down (Wolf! Fall1995/Winter 1996). New Mexico cattle ranchers were very opposed to the reintroduction but ranchers in Arizona were more open to it. Three Apache tribes that live close to the proposed reintroduction sites, opposed the wolf reintroduction. The White Mountain and San Carlos Reservations are just west of The Blue Range area. Both of these reservation helped with the Draft EIS but opposed the reintroduction mainly due to livestock interests (Wolf! Fall1995/Winter 1996).

To help address concerns about livestock predation, a compensation fund was set up, based on the Defenders of Wildlife (DOW) program. Defenders of Wildlife set up a privately funded program in 1988 to help with gray wolf reintroduction into Yellowstone, which proved to be very successful. Preserve Arizona's Wolves (P.A.WS), a non-profit organization dedicated to preserving the Mexican wolf, helped with the effort for the Mexican wolf fund. P.A.WS. calls this the "supply-side environmentalism", to utilize private resources in order to provide fast environmental solutions instead of waiting for government action (Wolf! No.4, 1994). It shifts the economic burden of the reintroduction program from the individual livestock owner to those that greatly support wolves. This fund is relied upon to help Arizona Fish and Game with Mexican Wolf program.

In July 1993, the USFWS sent out a time table which established the release of the Final EIS in March of 1995 and release of wolves by July of 1996 (Wolf! Spring/Summer 1996). Yet the guideline were not followed and the releases of the Draft EIS and the Final EIS were postponed several times. Lawsuits by the public and conservation organizations were pending, claiming the USFWS was in violation with their established timeline and the ESA guidelines.

In 1994, the captive Mexican wolf population was at 62 in the U.S. and 14 in Mexico (Wolf! No.2, 1994). A pair of wolves was exchanged between the U.S and Mexico to increase genetic diversity (Wolf! No. 2, 1994). A survey was conducted by USFWS to look for evidence of wolves in the wild. Some evidence was obtained on historical wolf sightings but no concrete evidence of present wolf existence in the wild was found. Mexico participated in surveying, Chihuahua, Durango, Sonora, and portions of adjacent states. During howling surveys, possible responses were reported along the Sonora/Chihuahua and Sierra Madre border, but no tracks were found to back up the evidence due to compact, dry ground (Wolf! No.4, 1994). In 1995, the captive population estimate was at 88 with 17 pairs established for the next breeding season (Wolf! No.1, 1995). The Clinton administration requested $537,000 for the wolf recovery program in 1995 but the House and Senate opposed the request (Wolf! No.1, 1995).

By winter of 1996, the Mexican captive wolf population was at 139 (Wolf! Fall1995/Winter 1996). Construction of a facility began at Sevilleta National Wildlife Refuge, about 70 miles south of Albuquerque, New Mexico. This facility is to be a holding pen to allow the wolves an acclimation period before they are released into the wild. It may also serve as an additional breeding facility. This site is ideal because of its similar environmental conditions to the reintroduction sites and it is secluded so human interference should be minimal. Ten wolves, five pairs are set for reintroduction. Some individuals will be kept in captivity to maintain viable, genetic material. By the summer the captive population of Mexican wolves was at 153, 138 adults and 15 pups (Wolf! Spring/Summer 1996).

The USFWS finally released the Mexican Wolf Draft EIS for public review and comment on June 21, 1995, a year after the confirmed date of May 1994 (P.A.WS November 15, 1995). June 1996 was the expected date for the final EIS release (P.A.WS February 14, 1996). Although by August, the final EIS release was postponed indefinitely. In March of 1996, Interior Secretary Bruce Babbit signed a "Record of Decision" formally approving the recommendations from the USFWS to reintroduce the endangered Mexican wolf into Arizona and New Mexico (Department of Interior 1997). By the spring of 1998, three family groups consisting of an adult pair and their offspring will be released on public lands in the Apache National Forest in eastern Arizona. The wolves will be allowed to disperse into the adjacent Gila National Forest in New Mexico. The total amount of habitat is almost 7,000 square miles. Wolves that stray onto public lands will be removed unless the owner wants them to stay. Additional family groups will be released each year until the goal of a self sustaining population of 100 wolves exists, possibly in 7-10 years (Department of Interior 1997).

The Final EIS was released in December of 1996 which recommended the release of the wolves as an "experimental and nonessential" population under the ESA. This allows Federal, State, and Tribal agencies and managers more flexibility in management. Wolves that prey on livestock will be removed by wildlife managers and livestock owners are allowed to kill a wolf caught attacking or threatening to do so on their private land. This decision came out of extensive public review. The USFWS held 14 public meetings, 3 formal public hearings and received nearly 18,000 comments from other agencies, organizations, and citizens (Department of Interior 1997). The Mexican wolves chosen for release will be selected from a captive population of 148 individuals that are maintained in zoos, wildlife sanctuaries, and other facilities in U.S. and Mexico (Department of Interior 1997). Those selected will be held at the Sevilleta National Wildlife refuge, in New Mexico and released into the wild after an acclimation and evaluation period. The candidates for release will be genetically well represented and less than five years old.

The significance of a designated wolf recovery area is to distinguish the legal status of any wolf that may be found there. When in the designated recovery area, a wolf is considered part of a nonessential, experimental population. Any wolf that is found within the experimental area but outside of the designated wolf recovery area, will be captured and returned to a captive program or re-located and released (FWS 1995). Any wolf found outside of the experimental area will be considered of wild origin with full protection status under the ESA, unless there is evidence of a radio-collar or identification that marks that individual as a member of the experimental population (FWS 1995).

Wolves will be reintroduced under the "soft release" technique (placing in pens to allow for acclimation, as mentioned) which is designed to reduce the likelihood of immediate dispersal away from the release site (USFWS #2, 1995). Approximately 5 family groups of captive raised Mexican wolves will be reintroduced over a period of 3 years into the White Sands Wolf Recovery Area. The goal is to reach a long-term sustainable population of 20 wolves (20 wolves within an area of 1,000 square miles)(USFWS #2, 1995). In the Blue Range, approximately 14 family groups will be released over a period of 5 years. The goal is to reach a long-term sustainable population of 100 wolves (100 wolves within 5,000 square miles)(USFWS #2, 1995).

In order to identify and monitor individual wolves, prior to placement in the holding pens, adult wolves will receive permanent identification marks and radio-collars. Pups will receive surgically implanted transmitters and will be recaptured when large enough, to be fitted with radio-collars. Wild pups will be captured and radio-collared and given permanent identification. Continued monitoring, research, and evaluation will occur throughout the process to evaluate the success or failure of different aspects of the program. Periodic progress reports will be prepared, and full evaluations will occur after 3 years for the WSWRA and 5 years for BRWRA which will recommend continuation or termination of the reintroduction effort (USFWS #2, 1995).

In the spring of 1997, 36 Mexican wolf puppies were born in 32 facilities in the U.S. and Mexico which increases the total population to 178 (P.A.WS August 5, 1997). Of the 36 puppies, 5 were born to two pairs of wolves at the facility in Sevilleta National Wildlife Refuge. They will be the first puppies set for release in the Blue Range Wolf Recovery Area in spring of 1998 (P.A.WS. August 5, 1997).

C. Mexican Wolf History Timeline

1630 AD: the first bounty in the New World was established in Massachusetts Bay Colony with authorization on one penny per wolf.

1600's (Late): livestock were introduced into the Southwest.

1694: an estimated 100,000 head of livestock were registered in northern Sonora by J.J Wagoner, an Arizona historian. First use of strychnine for predator control.

1758 : first scientific description of genus Canis which includes wolves, coyotes, and domestic dogs. Completed by Linneaus, a Swedish botanist and father of scientific classification. He used the domestic dog as the stereotype for description of the genus. Also first description of Canis lupus was developed based on wolves in Sweden, by Linneaus.

1763 : believed to be the first report of wolves in southwest

1851 : first record of wolves in Arizona

1880'-90's : livestock ranching increased in the southwest, wolves were seen as a greater threat, numbers of wolves were relatively large due to abundance of prey.

1893 : first official measure against wolves in Arizona and New Mexico was created. The "Territorial Bounty Act" allowed bounties to be paid for dead wolves.

1907 : Vernon Bailey, senior biologist with the U.S. Biological Survey, published under the U.S. Dept. of Agriculture, Wolves in Relation to Stock, Game, and The National Forest Reserves. It described detailed methods of wolf destruction.

1914 : Predatory Animal and Rodent Control (PARC) was established by Congress as a branch of the U.S. Biological Survey, to eliminate predators, prairie dogs and other pests of the southwest.

1920's (mid) : last wolves were trapped on Kaibab Plateau. Wolves were essentially eliminated from New Mexico.

1929 : first description of the Mexican wolf.

1940's : the "coyote-getter" or cyanide gun was introduced into southwest.

1942 : last wolf in northern Arizona was trapped 40 miles south of Winslow, Arizona. The last known wolves born in the wild in Southwest, were found, the pups were killed but the mother escaped.

1943 : last wolf trapped in Baboquivari Mountains in southern Arizona.

1947 : Arizona legislature passed a revision of the 1893 Bounty Law, authorizing a bounty of $50, and later $75, on wolves. This law was still in action in 1989.

1950's : compound 1080 introduced for predator control.

1959 : captive breeding program began in U.S. zoos. A total of 3 lineages were established but 2 were later abandoned because of genetic questions (not pure Mexican wolves).

1960 : a wolf was trapped and killed in Santa Cruz county just north of the Mexican border by predator control agent.

1973 : Mexican wolf was protected by the elimination of open hunting season by Arizona Fish and Game Department. The Mexican wolf was designated as a threatened subspecies by U.S. Bureau of Sport Fisheries and Wildlife (which became the USFWS).

1976 : Mexican wolf was protected under New Mexico state regulations.

1977 : USFWS issued a proposed rule in the Federal register listing the species Canis lupus as endangered in Mexico and the 48 contiguous states of the U.S. except Minnesota. At the same time the rule deleted all subspecies listings. Two males were captured in Mexico for the Mexican wolf captive breeding program.

1982 : Mexican wolf was listed by Arizona Game and Fish Department as extirpated from Arizona. Mexican Wolf Recovery Plan was completed and the ESA authored the "experimental, nonessential" classification for reintroduced species.

1984 : the USFWS and Arizona Fish and Game Commission made a formal agreement to conserve threatened and endangered wildlife and ecosystems in the state of Arizona.

1985 : first meeting of the Mexican Wolf Captive Management Committee, established by USFWS.

1986 : discussion began on possible reintroduction sites to be extensively surveyed and explored by USFWS and Arizona and New Mexico Game and Fish Departments (AGFD and NMGFD). The Mexican Wolf Coalition of New Mexico was founded as a private conservation foundation.

1987 : Genetic Assessment of the Current Captive Breeding Program for the Mexican Wolf (Canis lupus baileyi ) was produced by W. Shield, A. Templeton, and S. Davis. It was completed under contract from NMGFD. It provided a captive breeding strategy and discussed genetic analyses of various lineages already in programs.

1988 : Mexican Wolf was listed as endangered by AGFD. They began a public outreach and survey program. P.A.WS was created for the preservation of the Mexican Wolf and to provide public support for the reintroduction program.

1989 : captive population grew to 37 individuals.

1990 : Arizona Wolf Symposium was held in Tempe, Arizona for public education and response. AGFD wrote a proposal to the USFWS to fund an evaluation of four reintroduction sites: Blue Range Area, Chiricahua Mountains, Galiuro/Pinaleno Mountains, and Atascosa/Huachuca Mountains.

1991 : public meetings were held in Las Cruces, New Mexico and Tucson, Arizona. The USFWS, "Proposal and General Plan for Experimental Release of the Mexican Wolf" was formally released at the meetings. A compensation fund was set up in conjunction with Defenders of Wildlife and P.A.WS. A new Mexican Wolf Recovery Team was created. The House and Senate Appropriations committee did not approve any budget money for the reintroduction program in 1992.

1992 : target date for initiating the EIS for the reintroduction program. Captive population was up to 50, 41 at 9 facilities in the U.S and 9 at 3 facilities in Mexico, 24 males and 26 females.

August 1992 : second North American Wolf Symposium was held in Edmonton, Alberta. Data was presented showing that Canis lupus baileyi is genetically and taxonomically distinct from other subspecies of wolves. Arizona Game and Fish Commission approved the USFWS proposal for development of a site specific reintroduction plan of Blue Range area.

1993 : Mexican Wolf Coalitions of New Mexico and Texas and P.A.WS spoke with Congress about support from Federal appropriations for the reintroduction program.

In captive breeding programs throughout the U.S., 30 pups were produced by 5 adult pairs.

Five-Year Program Review and Assessment : PDF |  Mexican Wolf Recovery : Technical Component of the Five-Year Program Review and Assessment  PDF