Make your own free website on
Wolf History, Conservation, Ecology and Behavior
Wolfology Item # 1320
New Mexico Journal of Science
v.36 (1996)

Contact the publishing journal for information on acquiring the complete article
Case Study: The Mexican Wolf
D.R. Parsons
The Mexican wolf (Canis lupus baileyi) is the southern-most occurring and most endangered subspecies
of gray wolf (Canis lupus) in North America, historically occupying montane woodlands in the
southwestern United States (U.S.) and central and northern Mexico. It was extirpated from the wild in the
U.S. by private and government control campaigns and was listed as an endangered species in 1976. The
Mexican Wolf Recovery Plan recommends the establishment and maintenance of a captive population
and the re-establishment of a wild population. Captive propagation was initiated with 5 wild wolves
captured in Mexico from 1977 to 1980. In 1995, two additional captive populations were determined to
be pure through molecular genetic (DNA) analyses. Currently, there are 150 living wolves in the captive
population; and none are known to exist in the wild. The U.S. Fish and Wildlife Service (USFWS) has
proposed the reintroduction of a nonessential, experimental population of Mexican wolves. A draft
Environmental Impact Statement addresses relevant issues and concerns associated with the proposal.
There is broad public support for the recovery and preservation of the Mexican wolf. Most people
affiliated with or sympathetic to the livestock industry are opposed. This case study demonstrates the
diversity and complexity of scientific and policy issues involved in the conservation and restoration of
large carnivores.
The Mexican wolf (Canis lupus baileyi) is the southern-most occurring, most genetically unique, and most endangered subspecies of gray wolf (Canis lupus) in North America....While confusion and disagreement over North American gray wolf taxonomy persists, available data clearly support the conclusion that the Mexican wolf is a distinct subspecies.

Taxonomy and Historic Range
Hall and Kelson (1959), relying heavily on prior work of Young and Goldman (1944), described 24 subspecies of gray wolves in North America, five of which occurred in the southwestern United States and Mexico: C. l. baileyi, C. l. mogollonensis, C. l. monstrabilis, C. l. nubilus, and C. l. youngi. A taxonomic revision proposed by Bogan and Mehlhop (1983) lumped C. l. mogollonensis and C. l. monstrabilis into C. l. baileyi. In a recent reclassification of North American gray wolves, Nowak (1995) proposed reducing the original 24 named subspecies to five, of which C. l. baileyi is one. However, Nowak's reclassification differs from that proposed by Bogan and Mehlhop in that Nowak includes C. l. mogollonensis and C. l. monstrabilis with C. l. nubilus, not C. l. baileyi. It should be noted that no individual taxonomist or publication has "official" status or serves to rule on questions of mammalian taxonomy.
The classifications proposed by Hall and Kelson (1959), Bogan and Mehlhop (1983), and Nowak (1995)
were based on comparisons of morphological characteristics, primarily skull measurements, and all
concluded that C. l. baileyi is a morphologically distinct subspecies of gray wolf. Molecular genetic (DNA) analyses have identified distinct genetic attributes in Mexican wolves. Thus, there appears to be clear
consensus within the scientific community that C. l. baileyi is sufficiently distinct, both morphologically and genetically, to be taxonomically retained as a subspecies of the gray wolf. However, the lingering question of which formerly recognized subspecies belong to C. l. baileyi continues to confuse the delineation of the Mexican wolf's original distribution.
Requirements of the Endangered Species Act of 1973 (ESA) lead to the importance of delineating, as
accurately as is possible, the original distribution of the Mexican wolf. Regulations for implementing the
ESA state that "[t]he Secretary may designate as an experimental population a population of endangered
or threatened species that has been or will be released into suitable natural habitat...within its probable
historic range," [50 CFR 17.81 (a)] underlining added. The USFWS could be vulnerable to a legal challenge if it could be demonstrated that recovery efforts are being undertaken outside the subspecies' original range. For example, some people believe that areas proposed for reintroduction of Mexican wolves are outside that range. Thus, the taxonomic issues discussed above are inextricably linked to the discussion of original range below.
In the Mexican Wolf Recovery Plan (USFWS, 1982), the USFWS included the ranges of the former C. l.
mogollonensis and C. l. monstrabilis in the range of C. l. baileyi according to the recommendations of
Bogan and Mehlhop (1983). However, Nowak (1995) suggested that the original core geographical range
of C. l. baileyi extended just north of the Gila River, which bisects the Gila National Forest (part of the
Blue Range Wolf Recovery Area). Nowak (1995) did not describe the limits of the northeastern portion
of his proposed range for the Mexican wolf, but the line on his map bisects the proposed White Sands
Wolf Recovery Area then turns southeast through western Texas and enters Mexico just east of Big Bend
National Park. Nowak (1995) speculated that individuals from the geographic range of C. l. baileyi
historically dispersed into the range of wolf subspecies to the north, and that following the extermination
of wolves in the southwestern U.S., Mexican wolves expanded their range to fill the void.
In reality, the boundaries between ranges of adjacent gray wolf subspecies were wide zones of
intergradation where genetic mixing between subspecies occurred . The width of these zones relates to the ability of this species to disperse. Gray wolves are capable of dispersing hundreds of kilometers, with the longest known dispersal exceeding 885 km (550 mi). Thus for gray wolves, these zones of subspecies intergradation were likely hundreds of miles wide.
In light of the above discussion and a recommendation from the Mexican Wolf Recovery Team, the USFWS has concluded that a realistic delineation of the original range of the Mexican wolf includes the most restrictive range assigned to C. l. baileyi, plus a 322-km (200-mi) extension to the north and northwest of that area. This range delineation includes the ranges of C. l. baileyi as described by Young and Goldman (1944), Hall and Kelson (1959), and Nowak (1995); includes much of the expanded range resulting from the consolidation of subspecies proposed by Bogan and Mehlhop (1983); accommodates the range expansion of C. l. baileyi following extermination of adjacent wolf populations described by Nowak (1995); and is consistent with the dispersal capability of gray wolves....[T]he "probable historic range" of C. l. baileyi...includes portions of central and northern Mexico, western Texas, southern New Mexico, and southeastern and central Arizona.

The Mexican wolf preferred montane woodlands, presumably because of the favorable combination of cover, water, and prey availability. Most wolf collections came from pine, oak, and pinyon-juniper woodlands, and intervening or adjacent grasslands above 1,372 m (4,500 ft) in elevation. Wolves avoided desert scrub and semidesert grasslands, which provided little cover or water. Wooded riparian corridors were probably also used by Mexican wolves for travelling and hunting.

Life History
Little is known of the natural history of the Mexican wolf. Some data were obtained by trappers employed by the Predatory Animal and Rodent Control Service (PARCS). Numbers, weights, and details were often embellished. Weights of wild Mexican wolves range from 25-45 kg (54-99 lbs). Adult Mexican wolves ranged from 140-170 cm (4.5-5.5 ft) in total length (nose to tail), and averaged 72-80 cm (28.5-31.5 in) in shoulder height. The Mexican wolf like most other North American gray wolves has a range of pelage colors and patterns; however, solid white or black Mexican wolves are not documented.
The Mexican wolf probably preyed primarily on white-tailed deer (Odocoileus virginianus) and mule deer (O. hemionus). Elk (Cervus elaphus merriami), pronghorn (Antilocapra americana), javelina (Tayassu tajacu), beaver (Castor canadensis), rabbits (Sylvilagus sp.), hares (Lepus sp.), and small mammals likely provided alternative prey; food habits are not well documented. As livestock numbers increased in the late 1800's and native ungulate populations concurrently declined through unregulated subsistence and market hunting, the Mexican wolf began to prey on livestock. Today, livestock numbers are significantly lower, and wild ungulate populations have been restored in many areas.
Predation methods of Mexican wolves differed from those of other large predators (e.g., mountain lions, black bears, and grizzly bears) in Southwestern ecosystems. Wolves pursue their prey by chasing, sometimes over long distances, and often hunt in groups; while other large predators hunt singly and usually rely on ambush or opportunistic encounters with their prey. Thus, the evolutionary influence of Mexican wolves on their prey was unique and was not replaced in their absence.
Bednarz (1988) suggested that Mexican wolves form small family groups of from two to eight members when not molested, but data supporting this belief are generally lacking. Most information obtained regarding free-ranging Mexican wolves was provided by trappers who most often targeted lone wolves. Occasionally, groups of wolves were taken together, but the intensive control activities undoubtedly affected the structure of wolf social units, and eliminated the basis for scientific determination of pack size and social structure. Likewise, most data obtained on the productivity of wild Mexican wolves was provided by people who dug young wolves from dens, usually to kill them.
McBride (1980) reported a mean litter size of 4.5 from 8 dens in Mexico. Mean litter size before parturition for 8 females was 6.8, indicating a degree of mortality during or after birth. The size of 86 litters of Mexican wolves born in captivity ranged from 1-9 with a mean of 4.6. Captive females usually come into estrous between mid-February and mid-March. Gestation averages 63 days, with parturition occurring in April and May.

Population Status in the Wild
Wolves have inhabited the Southwest since the Pleistocene Epoch. Fossil remains have been reported from Arizona and New Mexico. Bednarz (1988) estimated 16.1 wolves per 1,000 km2 (386 mi2) or about 1,500 animals for the suitable habitat in New Mexico prior to control measures initiated by PARCS in 1915.
Many methods were used to exterminate Mexican wolves, including trapping with snares and steel leg hold traps, denning, shooting, and poisoning with sodium cyanide (used in the "coyote getter" device) and strychnine, arsenic, and compound 1080, which were placed in carcasses or other baits. Public and private bounties were paid. PARCS reported over 900 Mexican wolves killed in New Mexico and Arizona by government trappers or cooperators from 1915-1925, and it is believed that a greater number of wolves were killed for bounties from 1890 to 1915.
The Mexican wolf is believed to be extirpated from the wild in the U.S. Bednarz (1988), utilizing a regression model, proposed 1942 as the estimated year of extirpation in New Mexico. McBride (1980) estimated that fewer than 50 Mexican wolves existed in the states of Chihuahua and Durango, Mexico, and speculated that no more than 50 adult breeding pairs existed in Mexico in 1978. The present status of wild populations in Mexico is unknown but thought to be much lower than McBride's estimates for 1978. Recent surveys in Mexico have not confirmed its presence in the wild. It appears very unlikely that viable populations remain in Mexico, if any remain at all. The USFWS continues to receive unconfirmed reports of wolf sightings primarily from U.S./Mexico border areas of Arizona and New Mexico. These "wolves" could be Mexican wolves dispersing from Mexico or escaped or abandoned pet wolves, wolf-dog hybrids, or large dogs.
....The Mexican wolf is listed as an endangered species throughout Mexico. However, enforcement of this
legal protection is problematic.

Recovery Efforts
Under an agreement between the U.S. and Mexico, Roy McBride (Alpine, Texas) captured five Mexican
wolves between 1977 and 1980 in Durango and Chihuahua. These wolves (four males and one pregnant
female) were transferred to the Arizona-Sonora Desert Museum in Tucson, Arizona, to establish a
captive breeding program.
The Mexican Wolf Recovery Team was formed by the USFWS in August 1979. The team prepared the Mexican Wolf Recovery Plan which was approved and signed by the Director of the USFWS and the Director General of the Direccion General de la Fauna Silvestre (Mexico) on September 15, 1982. Citing human demands for space and resources present in historical wolf habitat, the team concluded that there was "no possibility for complete delisting of the Mexican wolf". The unstated implication is that down-listing to a threatened status is the best that could be hoped for. The plan contains the following objective: "To conserve and ensure the survival of C. l. 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 13,000 km2 (5,000 mi2) area within the Mexican wolf's historic range". The two key components of this objective are captive breeding and re-establishment of a wild population.
The recovery plan is being revised. Based on advances in conservation biology and the application of a population viability model, the current recovery objective for the Mexican wolf will be reviewed and revised. Specific goals for down-listing to a threatened status and de-listing the Mexican wolf will be established.
Given the natural and human-caused isolation of areas of suitable habitat for the Mexican wolf, a number of separate reintroductions will likely be required to ensure long-term conservation of the subspecies. Re-establishment efforts will most likely result in a metapopulation (two or more isolated subpopulations), which may require active management to ensure adequate gene flow among re-established subpopulations.

Captive Breeding Program
Between 1977 and 1980, five wolves (four males and one pregnant female) were live-captured in Durango and Chihuahua, Mexico, to establish a captive population of Mexican wolves called the "certified" lineage.
The captive breeding program for certified Mexican wolves was initiated at the Arizona-Sonora Desert Museum in Tucson, Arizona, with the delivery of the five wild-caught wolves beginning in 1977 and the birth of a litter of five pups by the captured pregnant female in 1978. The only female pup in this litter died at the age of 4 days. Two of the wild-caught males and the lone female later bred and produced offspring in captivity. In 1981 at the Wild Canid Survival and Research Center in Eureka, Missouri, female number 5 gave birth to her second litter in captivity (one male and three female pups). All four of these pups survived and reproduced. By 1983, the captive breeding program was firmly established with the birth of three litters totaling 15 pups.
Based largely on the results of DNA studies, two additional lineages of captive Mexican wolves, one each in the U.S. and Mexico, were certified for inclusion in the official breeding program for Mexican wolves in July 1995. The U.S. population is referred to as the Arizona-Sonora Desert Museum/Ghost Ranch (Ghost Ranch) lineage and the Mexican population is referred to as the Parque Zoologico de San Juan de Aragon (Arag0n) lineage.
The Ghost Ranch lineage consists of 21 known animals, all descended from two founders. The original sire was live trapped in 1959 near Tumacacori, Arizona. The founding female was purchased as a pup in 1961 by a Canadian tourist in Yecora, Sonora, Mexico. A question remains as to whether it was born in the wild or in captivity.
The Aragon lineage consists of eight animals held at the Parque Zoologico de San Juan de Aragon in Mexico City. The origin of this population cannot be traced to the wild or to known founding animals.
As of August 1996, the captive population of Mexican wolves consisted of 150 individuals held in 29 zoos and wildlife sanctuaries in the U.S. and Mexico. This population is the result of captive breeding from the three officially accepted lineages of Mexican wolves. There are 121 wolves in the certified lineage, 21 in the Ghost Ranch lineage, and 8 in the Aragon lineage. Twenty-four facilities hold 121 Mexican wolves in the U.S.; and five facilities hold 29 Mexican wolves in Mexico. Three Certified/Ghost Ranch and three certified/Aragon cross-lineage pairs have been established and are expected to produce pups in 1997.
Management of the captive population follows a Species Survival Plan (SSP) developed and implemented by the American Association of Zoos and Aquariums....The SSP objective is to establish and maintain a captive population of at least 240 animals with a minimum of 17 breeding pairs. Computer models predict that at least 75% of the gene diversity of the founding wolves would be conserved for the next 50 years with a professionally-managed population of this size. Population managers attempt to maximize retention of the genetic diversity (number of different alleles or gene forms) of the seven wolves that founded the population. This is accomplished by equalizing founder representation and minimizing inbreeding throughout the population through deliberate mate selection. A detailed, computerized studbook tracks the pedigree of every member of the population. A sophisticated "computer dating" program is used to match wolves for breeding.
Some concern has been expressed over the limited genetic base (seven founders) of the captive population. With this few founders, a certain level of inbreeding cannot be avoided. However, no evidence of "inbreeding depression" (decrease in vigor, viability, or fecundity that may result from excessive inbreeding) has been detected in the population. The recent inclusion of two additional breeding lines will increase gene diversity and further reduce the likelihood of inbreeding depression in the population.
Recent analyses of allele frequencies at ten nuclear microsatellite loci (gene locations) in Mexican wolves from the three different lineages, other gray wolves, red wolves, coyotes, and domestic dogs provide the most definitive information on the ancestry and genetic purity of the three captive wolf lineages. From these and other studies, the Genetics Committee of the Mexican Wolf Recovery Team concluded that wolves in the three lineages are all Mexican wolves and that there is no indication of any past cross-breeding with coyotes, dogs, or northern gray wolves. These studies also provided convincing evidence that two of the four founders of the certified lineage were probably mother and son, reducing the number of unrelated founders for this population to three. Thus the total captive population of Mexican wolves stems from seven founders. Captive breeding efforts truly have rescued this endangered subspecies from the brink of extinction.

Re-establishment of Wild Populations
The USFWS is constructing a six-pen wolf management facility on the Sevilleta National Wildlife Refuge near Socorro, New Mexico. The purposes of this facility are to provide needed space for captive Mexican wolves, to provide greater flexibility for managing the captive population, and, if reintroduction is approved, to foster desirable attributes in wolves selected for release to the wild....
Reintroduction of captive-raised Mexican wolves to establish a wild population of about 100 wolves has been proposed. If approved, about five family groups (two groups per year) of surplus captive-raised Mexican wolves would be "soft released" into the White Sands Wolf Recovery Area in south-central New Mexico or about 15 family groups (three groups per year) would be soft released into the Blue Range Wolf Recovery Area (BRWRA) in east-central Arizona and west-central New Mexico. Both areas could eventually be used if feasible and necessary to achieve the 100-wolf population objective. Continued population growth would result from natural reproduction achieving a final self-sustaining population of about 100 free-ranging wild Mexican wolves in 8-10 years if the BRWRA is used; about 20 wolves in 3 years if the WSWRA is used; and about 120 wolves if both areas are used.
The Blue Range Wolf Recovery Area includes all of the Apache and Gila National Forests in east-central
Arizona and west-central New Mexico, encompassing about 17,700 km2 (6,850 mi2). Elevations range from under 1,200 m (4,000 ft) in the semi-desert lowlands and along the San Francisco River to 3,350 m (11,000 ft) on Mount Baldy, Escudilla Mountain, and the Mogollon Mountains. Vegetation varies from grasses and shrubs in the lowest areas; pinyon, juniper, and evergreen oaks in the foothills at low to middle elevations; and mixed conifer stands at higher elevations. Open grassy meadows occur throughout, especially in the northern and higher elevation areas. Water is abundant in natural springs, streams, and rivers. Wild ungulate species include white-tailed deer, mule deer, elk, pronghorn, bighorn sheep (Ovis canadensis), and javelina. The area supports an estimated 57,000 deer and 16,000 elk. About 82,600 head of cattle were permitted to graze on 69% of the area in 1993, although actual numbers were probably lower. Other prevalent uses include forestry, mining, and various forms of outdoor recreation. The entire area is open to public use.
The White Sands Wolf Recovery Area includes all of the White Sands Missile Range, Holloman Air Force Base, White Sands National Monument, San Andres National Wildlife Refuge, Jornada Experimental Range and a strip of mostly Bureau of Land Management and State of New Mexico lands west of the missile range. It encompasses the San Andres and Oscura Mountains and portions of the Tularosa Basin and the Jornada del Muerto. The White Sands Wolf Recovery Area contains about 10,400 km2 (4,000 mi2). Elevations range from around 1,200 m (4,000 ft) in the desert basins to 2,700 m (9,000 ft) in the San Andres Mountains. Vegetation varies from grasses and shrubs in the basins and lower foothills; pinyon and juniper above 6,000 feet; to a small stand of ponderosa pine on Salinas Peak in the San Andres Mountains. Water is present at several permanent and intermittent springs and artificial water sources. Native wild ungulate species present include mule deer, pronghorn, and desert bighorn sheep (Ovis canadensis mexicana). Feral horses and introduced gemsbok (Oryx gazella) are also present. The area supports an estimated 7,500 mule deer and 1,700 gemsbok; other ungulates occur in very limited numbers. About 2,100 head of cattle graze on the area west of White Sands Missile Range. The missile range is not open to grazing by domestic livestock or to general public use. The most prevalent uses are military testing and training.
....The USFWS will designate the released wolves and their progeny as one "nonessential, experimental
population" under provisions of section 10(j) of the ESA. The USFWS believes that this designation will provide necessary management flexibility for addressing potential wolf-human conflicts, especially livestock depredation. A nonessential, experimental population must be established by a federal regulation which defines the boundaries of the population and sets forth special rules for its management and protection. Special rules usually allow for more liberal legal "taking". ( The term "take" means to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or to attempt to engage in any such conduct of members of the experimental population than would be allowed under the ESA for endangered species.)....

Few controversial endangered species recovery projects escape litigation, and Mexican wolf recovery is no exception. In April 1990, a coalition of regional and national environmental organizations filed suit against the departments of the Interior and Defense alleging the agencies' failure to implement provisions of the ESA (Wolf Action Group, et al. v. United States, Civil Action No. CIV-90-0390-HB, U.S. District Court, New Mexico). The Plaintiffs claimed that the USFWS had failed to implement the Mexican Wolf Recovery Plan as required by section 4(f)(1) of the ESA, especially the plan's recommendation for the reestablishment of a wild population of Mexican wolves. The Department of Defense was charged with not utilizing their authority to further the purposes of the ESA by "carrying out programs for the conservation of endangered species" as required under section 7(a)(1) of the act. The U.S. Army White Sands Missile Range (WSMR) was being considered by the USFWS as a potential Mexican wolf reintroduction area when the Army withdrew it from further consideration in 1987. The WSMR Commander was responding to a USFWS regional policy of not reintroducing wolves on any area where the State game and fish department or land management agency objected. The plaintiffs termed this policy the granting of "veto power" over wolf recovery by the USFWS to the States and Federal land management agencies; and they claimed that the USFWS had violated the ESA by establishing this policy.
The litigants negotiated a stipulated settlement agreement in 1993, wherein the USFWS agreed to implement the Mexican Wolf Recovery Plan as expeditiously as possible. The USFWS also agreed to expedite completion of the National Environmental Policy Act (NEPA) process for its proposal to reintroduce Mexican wolves to the wild, which would consider an array of reintroduction sites, including the WSMR.
Shortly after the plaintiffs issued their notice of intent to sue in 1990, the Army reversed its decision to withdraw WSMR from consideration as a wolf reintroduction area. In October 1990, the USFWS hired a full-time Mexican Wolf Recovery Coordinator to expedite implementation of the Mexican Wolf Recovery Plan; and in early 1991, a general plan for reintroducing Mexican wolves to the wild was developed by the USFWS.

National Environmental Policy Act Compliance
....In order to comply with the provisions of NEPA [National Environmental Policy Act], the USFWS began to collect public input for the preparation of an Environmental Impact Statement (EIS) on the proposed reintroduction plan in April 1991. Four public "scoping" meetings were held prior to the preparation of a draft EIS by an interagency, interdisciplinary team in June 1995. Fourteen public open-house meetings and three formal public hearings were held to receive public comments on the draft EIS. Nearly 18,000 comments or opinions were received, reviewed by the USFWS, and will be responded to in the final EIS, which is expected to be released in the fall of 1996....
Socio-political Aspects
Public support for Mexican wolf recovery is strong and broad-based.
A poll conducted in 1995, showed that, statewide, about 60% of New Mexico residents supported reintroduction of Mexican wolves; while 22-25% opposed it, depending on the location (Arizona versus New Mexico, respectively). In the four primarily rural counties in the proposed release areas, about 50% of residents polled supported reintroduction, while about 32% opposed it. Biggs (1988) found that 79% of New Mexico residents, statewide, supported Mexican wolf reintroduction into New Mexico, while 79% of ranchers opposed it. Biggs (1988) also found that 21% of ranchers polled supported wolf reintroduction. A majority of statewide and rural Arizona residents also support reintroduction of Mexican wolves into its former forest and mountain habitats in Arizona.
Despite demonstrated public support, most elected and appointed officials who have stated their position oppose Mexican wolf reintroduction. This includes the governors of both New Mexico and Arizona, the Director of the New Mexico Department of Game and Fish, and the New Mexico Game and Fish Commission. The Arizona Game and Fish Department and Commission support a controlled experimental release on White Sands Missile Range, before they would consider endorsing a release in Arizona.

The Mexican wolf is a unique life form that historically contributed to the overall biological diversity and ecological functioning of Southwestern ecosystems and the continued evolution of species it preyed upon. Deliberate eradication efforts driven by the politics of the late 1800s and early 1900s nearly caused the extinction of the Mexican wolf. Politics of the late 1900s provide hope for the preservation of the unique mix of genes molded by thousands of years of evolutionary pressure that form what we now recognize as the Mexican wolf and the restoration of its unique role in the ecosystem.
....Socio-political aspects of Mexican wolf recovery are complex and public opinion is strongly divided, with proponents out-numbering opposers by about 2 to 1. Positions of elected officials often run counter to the opinion of a majority of their constituents, suggesting influences by special interests or a lack of knowledge or accurate information on the subject.
....The are no known biological obstacles to Mexican wolf recovery. Suitable, genetically surplus animals from the captive population are available for reintroduction and suitable reintroduction areas exist. The successful reintroduction of red wolves in North Carolina demonstrated that captive-raised wolves can readily adapt to a wild environment. The successful reintroduction of northern gray wolves to Yellowstone National Park and central Idaho demonstrated that socio-political obstacles to wolf recovery are not insurmountable.
....Earlier authors have doomed the Mexican wolf to extinction or permanent life in captivity. However, a strong tide of public support for restoration of predators to their native ecosystems has resulted in the re  establishment of red wolves, northern gray wolves, bald eagles, peregrine falcons, sea otters, and black-footed ferrets to portions of their former ranges. Perhaps the Mexican wolf will also be given the opportunity to resume its unique ecological role in the southwestern U.S.

References: 30