The Mexican gray wolves in the SSP are not owned by any one zoo. Instead, they are placed on loan to a zoo or wildlife facility by the U.S. Fish & Wildlife
Service and the Mexican government. Decisions on transfers, breeding, and the like, are made at the annual Species Survival Plan (SSP) meeting in July, where
each facility is invited to participate in the decision making process for the upcoming year. It is crucial to the survival of the species that these decisions
are made based on science rather than each zoo's independent management wishes. Careful management is one reason that this SSP has been so successful in it's
efforts to preserve the world's most endangered wolf.
Description: Gray wolves are the largest of the canine family. The Mexican gray wolf is the rarest, smallest, and most genetically
distinct subspecies of gray wolves known to live in North America. Mexican wolves typically weigh between 50-80 lbs. and have a varied coat color including
mixtures of black, gray, white, red, and brown.
Habitat and Range: The range of the Mexican wolf is believed to have included central and southeastern Arizona, southern New Mexico,
southwestern Texas and in the Sierra Madre and adjoining highlands of Mexico. Their habitat includes oak forests, oak/pine forests, or pine forests adjacent
to open areas at elevations ranging from 4500-9000 feet above sea level. Unconfirmed reports persist from Durango and Chihuahua, with biologists attempting
to confirm actual wolf presence in these areas. (See Conservation section below).
Behavior and Communication: The wolf pack is one of nature's most sophisticated social orders, as well as one of the most intensively
studied. A wolf pack is usually a family group of five to eight animals, usually consisting of a pair of breeding adults and their young of 1 or 2 years old. The
breeding pair is likely to be the oldest, largest, and strongest wolves in the pack. They are known as the dominant wolves and are usually the only members of
the pack to produce pups. Any wolf can become dominant. To do so, it must find an unoccupied territory and a member of the opposite sex with which to mate. Or,
more rarely, it moves into a pack with a missing dominant wolf and take its place, or perhaps kills the dominant wolf and usurps its mate.
Wolves use body language to convey the rules of the pack and rule number one says that the pack is made up of leaders and followers. The dominant male
and female are in charge of the pack. To communicate dominance, they carry their tails high and stand tall. Less dominant wolves exhibit submissive behavior
by holding their tails down and often lower their bodies while pawing at the higher-ranking wolves. The pack has a complex social hierarchy maintained through
a variety of vocalizations, body postures, and scent marking.
Wolves have keen senses of sight, hearing, and smell and can travel at approximately 5 miles per hour for long periods of time while hunting or traveling
within their territory. A wolf pack may spend 8 - 10 hours a day on the move and may cover 40 miles a day during winter hunts. Wolves can reach a top speed of
about 40 miles per hour for short periods of time.
The average pack size for the Northwestern wolf is generally 6-12 wolves, with some packs as large as 20-30 with one in YNP documented at 37.
Diet: Wolves evolved as a predator of large hoofed mammals, with a tightly organized social structure, which enables them to work
cooperatively to bring down preys much larger than themselves. They will usually kill what is easiest to catch such as the weak, sick, injured, old and very
young. Wolves will also scavenge carrion, and will take healthy, strong animals when possible. Living in a "feast or famine" world, wolves often go
several days without successfully making a kill, but can gorge themselves and consume over 20 lbs. when the hunt has been successful. The Mexican wolf's major
prey species were believed to include elk, mule deer, whitetail deer, pronghorn, javalina, and other small mammals.
Habits and Adaptations: The wolf pack is one of nature's most sophisticated social orders, as well as one of the most intensively
studied throughout the world. A wolf pack generally consists of an adult breeding pair of wolves and their offspring over several years. Most often, the
offspring will leave their home pack by 3-4 years of age and start their own pack with another wolf of the opposite sex. It is believed that Mexican gray wolf's
general behavior is similar to other subspecies of gray wolf by having a complex social hierarchy maintained through vocalizations, body postures, and scent
marking. Wolves have keen senses of sight, hearing, and smell and can travel at ~ 5 miles per hour for long periods of time while hunting or traveling within
their territory.
Breeding and Maturation: The pack's social structure generally determines which wolves will breed, usually only the adult breeding
pair, which will produce a single litter of pups. However when prey is abundant, a wolf pack may occasionally have multiple litters born that spring. The
breeding season is usually late January through early March, with a litter of 2-6 pups born 63 days later. After 4-6 weeks, the pups usually leave the den
and begin to investigate their surroundings. As the pups mature, the pack will move to a "rendezvous" site within their territory. Wolves generally reach
adult size by 10 months of age, and live 10-14 years in captivity.
Conservation: Intensive efforts by both private individuals and government agencies led to the eradication of the Mexican wolf through
most of its historic range. In 1976, the Mexican wolf was listed as an endangered species under the Endangered Species Act. Between 1977 and 1980, five
Mexican wolves were captured in Mexico under a joint agreement between the United States and Mexico. These original wolves, and two additional lineages of
captive wolves added in 1995, make up the captive breeding population that is now managed by the Mexican Gray Wolf Species Survival Plan (SSP) for the U.S.
Fish & Wildlife Service.
In March 1998, the howl of the Mexican wolf could once again be heard echoing through the hills of the Blue Mountain Range in Arizona. Wolves that are
potential candidates for release are evaluated on several factors including their genetic make-up, breeding history, and enhanced fear of humans. Wildlife
biologists use a "soft release" method, which allows the wolves to adjust to the release area for a period of time before the pen doors are opened.
Reintroduced wolves are designated as a "nonessential experimental population" under the ESA. This will allow for greater management flexibility
relating to livestock depredation issues, major land use restrictions translocations, captures, and other monitoring needs. International wolf experts rate
the recovery of the Mexican wolf as the highest priority of gray wolf recovery programs worldwide. In July 2007, there were ~300 Mexican wolves in captivity
in the U.S. and Mexico and ~60 wolves living free in Arizona and New Mexico.