Mexican Wolf Recovery
The Mexican gray wolf (Canis lupus baileyi) is the most genetically distinct subspecies of gray wolf in North America, as well as the smallest in size. A typical Mexican wolf is about 4.5- 5.5 feet long, from snout to tail, weighs from 50 to 90 pounds, and has a coat with a mix of buff, gray, red and black. Like all wolves, the Mexican wolf communicates using body language, scent marking and vocalization. The main prey for Mexican wolves is elk making up 74% of their diet. Other prey species include white-tailed deer, mule deer, javelina, jack rabbit, cottontail rabbits and smaller mammals.
Commonly called "lobo", the Mexican gray wolf has all but disappeared from its historic range in the southwestern United States and throughout Mexico. Predatory controls from the late 1800s to the mid-1900s made it the rarest gray wolf in North America. By the late 1970s, the Mexican gray wolf had virtually disappeared in the southwestern United States. It was listed as endangered on the federal endangered species list in 1976. An initial recovery objective of a wild population of at least 100 wolves over 5,000 miles of its historical range were approved by the U.S. Fish and Wildlife Service (USFWS) and the Direccion General de la Fauna Silvestre in Mexico in a 1982 recovery plan. The International Union for Conservation of Nature (IUCN) considers Mexican wolf recovery the highest priority for wolf conservation worldwide.
In 1997, a plan was approved calling for the reintroduction of Mexican wolves in Arizona and New Mexico. In March 1998, 11 Mexican gray wolves in three family groups were released into the wilds of the Apache National Forest of southeastern Arizona. Two additional wolves were released later that year. The highlight of the recovery program took place in 1998 when, for the first time in 50 years, a Mexican gray wolf pup was born in the wild.
Illegal shooting still remains the number one killer of wolves along the Arizona-New Mexico border having claimed 61 wolves since 1998. The US Fish & Wildlife Service revised the rules in January 2015 to allow for broader roaming privileges letting the wolves roam outside of the current Blue Range Wolf Recovery Area, which is considered too limited by scientists. This would allow wolves to naturally disperse into other places with suitable habitat throughout the southwest, but they will impose an artificial, and politically-based boundary at Interstate I-40. Wolves are still prohibited from establishing territories in the Grand Canyon region. Environmentalists and some ranchers agree that the human-wolf conflict could be eased if wolves weren't so concentrated.
Wolf recovery requires both captive breeding and reintroduction to the wild. Captive management is necessary to increase the population and to minimize the potential for in breeding depression. Reintroduction is essential to ensure that Mexican wolves exist in the wild and persist as more than just a population of zoo wolves. The first captive-reared Mexican wolves were reintroduced into the Blue Range Wolf Recovery Area beginning in January 1998. Immediately prior to reintroduction, no wild Mexican wolves were thought to remain in the U.S. or Mexico.
Currently, there are about 97 Mexican wolves roaming free in the wild. This is the first time the wild population has reached the initial 100-wolf population target for the Blue Range Wolf Recovery Area projected to be reached by 2006. There are also currently about 300 wolves at 52 captive breeding facilities throughout the United States and Mexico. (note: having 100 wolves in the Blue Range Wolf Recovery Area would not mean that wolves had been recovered to AZ or the southwest…there are still other areas, such as the Grand Canyon Ecoregion, the Southern Rockies and the Sky Islands, that provide suitable wolf habitat, and need to be considered in order for the Fish and Wildlife Service to accomplish the goal set forth by the Endangered Species Act of recovering wolves to a significant portion of their historic range.).
To read more about the feasibility of Wolves in the Grand Canyon Ecoregion, go to:
U.S. Fish & Wildlife Service's Mexican Gray Wolf Recovery Program
Brown, Wendy. El Lobo Returns. International Wolf; 1998. 8(4): 3-7.
United States Fish and Wildlife Service. Mexican Wolf Recovery Program: Natural History and Recovery Fact Sheet. 1997.
United States Fish and Wildlife Service. Mexican Wolf Recovery Program: Answers to Frequently Asked Questions about the Reintroduction of Mexican Wolves in the Southwest. 1997.
Wildlife Committee of the Rio Grande Chapter of the Sierra Club and the Mexican Wolf Coalition. The Mexican Wolf. Albuquerque, NM: Sierra Club; 1993.
(Most of the information above is from The International Wolf Center website www.wolf.org)
Predation is an important ecological process
Aldo Leopold, the father of modern wildlife management and author of A Sand County Almanac, admonished wildlife managers to retain all the pieces of our ecosystems(1953). Using modern analysis, present day ecologists are finding Leopold's directive to be right on the mark. Predation and particularly predation by large carnivores is a necessary component of all healthy ecosystems. Study after study has shown that predator loss leads to biodiversity loss (Diamond 1992). Large predator presence is so important, in fact, that conservation biologist John Terborgh (1988) wrote that "Disrupting the balance by persecuting top carnivores, by hunting out peccaries, pacas, and agoutis, or by fragmenting the landscape into patches too small to maintain the whole interlocking system, could lead to a gradual and perhaps irreversible erosion of diversity at all levels - both plant and animal." Recognition of this importance has prompted leading wildlife professional organizations such as The Wildlife Society and The Society for Conservation Biology, to dedicate special issues of their journals expressly to predator ecology and conservation. Moreover, these scientific societies have placed the restoration of predators high on their list of conservation priorities.
Predation does not always translate into lowered prey numbers
Although many quite vigorously contend that every bite a wolf or other predator takes out of a prey species adds to the other mortality factors already impacting prey populations, predator-prey relationships are rarely that simple (Krebs 1997). For example, in the Adirondacks of New York state, a healthy wolf population is expected to take approximately 4,000 white-tailed deer per year (Hosack 1996). But nearly 18,000 deer die each year of starvation during the harsh winters. Does that mean that after wolf reintroduction mortality is going to jump to 22,000 per year? Probably not. A more likely scenario is that mortality will be compensatory rather than additive and the region would experience an equivalent reduction in winter mortality. In simple terms, wolves would kill the animals that are most likely to die anyway instead of killing an additional amount over the normal winter die off.
In addition, wolves and other predators often have indirect effects on prey population dynamics. In Washington state's Olympic National Park, elk reproduction appears to be dampened because herds are dominated by older females who typically have fewer twins. As wolves preferentially prey on older animals (Pimlott et al. 1969), their future presence could actually increase overall reproduction in the herd. Moreover, reduction in adult ungulate numbers has been shown to increase fawn survival (White and Bartmann 1997).
If the biota, in the course of aeons, has built something we like but do not understand, then who but a fool would discard seemingly useless parts? To keep every cog and wheel is the first precaution of intelligent tinkering. --- Aldo Leopold
All predators serve different ecological roles
Some people mistakenly believe that all predators serve the same function. But while coyotes and wolves appear to be very similar, their roles and impacts on ecosystems are very different. Wolves are coursing predators, which means that they tend to chase their prey until they find an animal that is weak. This is very different from the opportunistic way coyotes generally hunt--taking whatever crosses their path. Wolves are also pack hunters who hunt cooperatively and whose populations respond very quickly to increases or decreases in prey availability. Coyotes are more individualistic: hunting in smaller units and responding very quickly to increases in the prey bases and very slowly to decreases due to the adaptability of their hunting skills. As a consequence of their different behaviors, they have different impacts on their prey. Wolves tend to eliminate the old, sick, and genetically inferior animals from populations (Pimlott et al. 1969) and coyotes, like bears and cougars, seem to take animals without regard to their condition (O'Gara et al. 1988).
Likewise, other predators hunt differently and take different animals at different times and under different circumstances. Predator-prey relationships are very complex and have evolved over thousands and thousands of years. As our understanding of the interplay between predators and prey has increased, so has our acknowledgment these relationships should be maintained intact.
Large predators control smaller predators
In 1988, Michael Soulé, founder of The Society for Conservation Biology, documented the phenomenon known as meso-predator release (Soulé et al. 1988). He found that removal of large predators led to a tremendous increase in smaller predators. When wolves are eliminated coyote populations explode. Likewise, when coyotes are removed, foxes prosper. The overall result is an increase in the impact of predators on prey. To illustrate this last point, consider that wolf expert L. David Mech has estimated that each reintroduced wolf pack (10 wolves) in Yellowstone will displace 50 coyotes. When looked at from a hunter's point of view, it seems clear that 1000 pounds of wolves will require less food than 1750 pounds of coyotes. Since the reintroduction in 1995, there are now 80% less coyotes in the Yellowstone region.
Real life examples of meso-predator release abound. When red wolves disappeared from the Southeast coyotes moved in and raccoons increased. In Mississippi this greatly impacted wild turkey reproduction (Miller et al. 1997). Similarly, removal of coyotes in the prairie pothole region benefited fox populations but lowered duck nest success by 15% (Sovada et al. 1995). Fortunately, two recent studies in the Northern Rockies (Arjo et al. 1997 and Crabtree, unpub.) demonstrate that these trends can be reversed. Both studies indicated that recolonizing and reintroduced wolves are displacing and in some instances killing coyotes. The remaining coyotes are relegated to the margins of occupied wolf habitats and are making dietary shifts back to smaller prey items such as rodents.
Armed with a new understanding of the role of predators, public opinion about predators has shifted dramatically (Brunson et al. 1997). Hopefully, that shift can be translated into predator management, conservation and restoration policies that are driven by the best available science and that strive to maintain appropriate predator assemblages in all natural areas across our nation.
Arjo, W.M., R.R. Ream, and D. Pletscher. 1997. The effects of wolf colonization on coyote behaviors, movements, and food habits in northwestern Montana. *
Brunson, M., T.A. Messmer, D.G. Hewitt, and D. Reiter. 1997. North American public attitudes toward predators, predation, and predator management. *
Diamond, J. 1992. Must we shoot deer to save nature? Natural History. 2-8.
Hosack, D. 1996. Biological potential for eastern timber wolf re-establishment in Adirondack Park. Wolves of America conference Proceedings. 24-30.
Krebs, C.J. 1997. The role of predation theory in wildlife science and management.*
Leopold, A. 1953. A Sand County Almanac with essays on conservation from Round River. New York: Ballantine Books. 190.
Miller, D.A., L. W. Burger, B. D. Leopold, and G.A. Hurst. 1997. Wild turkey hen survival and cause-specific mortality in Central Mississippi. *
O'Gara, B.W. and R.B. Harris. 1988. Age and condition of deer killed by predators and automobiles. 52:316-320.
Pimlott, D.H., J.A. Shannon, and G.B. Kolenosky. 1969. The ecology of the timber wolf in Algonquin Provincial Park. Can. Dep. Lands For. Res. Branch Res. Report. No. 87.
Soulé, M.E., D.T. Bolger, A.C. Alberts, J. Wright, M. Sorice, and S. Hill. 1988. Reconstructed dynamics of rapid extinctions of chaparral-requiring birds in urban habitat islands. Conservation Biology. 2:75-92.
Sovada, M.A., A.B. Sargeant, J.W. Grier. 1995. Differential Effects of Coyotes and Red Foxes on Duck Nest Success. Journal of Wildlife Management. 59:1-9.
Terborgh, J. 1988. The big things that run the world. Conservation Biology. 2:402-403.
White, G.C. and R.M. Bartmann, 1997. Effect of density reduction on overwinter survival of mule deer fawns. *
*Denotes scientific findings presented at the 1997 Annual Meeting of The Wildlife Society in Snowmass, Colorado. September 21-27.
Understanding Wild Wolves
Wolves are highly intelligent. Their acute hearing and exceptional sense of smell - up to 100 times more sensitive than that of humans - make them well-adapted to their surroundings and to finding food. Some researchers estimate that a wolf can run as fast as 40 miles an hour. Wolves have been known to travel 120 miles in a day, but they usually travel an average of 10 to 15 miles a day. Wolves live, travel, and hunt in packs of four to seven animals, consisting of an alpha, or dominant pair, their pups, and several other subordinate or young animals. The alpha female and male are the pack leaders, tracking and hunting prey, choosing den sites, and establishing the pack's territory. The alpha pair mate in January or February and give birth in spring, after a gestation period of about 65 days. Litters can contain from one to nine pups, but usually consist of around six. Pups have blue eyes at birth and weigh about one pound. Their eyes open when they are about two weeks old, and a week later begin to walk and explore the area around the den. Pups romp and play-fight with each other from a very young age. Scientists think that even these early encounters establish hierarchies that will help determine which members of the litter will grow up to be pack leaders. Wolf pups grow rapidly, reaching 20 pounds at two months and full size in a year. All adults share parental responsibilities for the pups. They feed the pups by regurgitating food for them from the time the pups are about four weeks old until they learn to hunt with the pack.
A wolf pup is the same size as an adult by the time he or she is about a year old, and is able to mate by about two years of age. Pups remain with their parents for at least the first year of their of their lives, while they learn to hunt. During their second year of life, when the parents are raising a new set of pups, young wolves can remain with the pack, or spend periods of time on their own. Frequently, they return in autumn to spend their second winter with the pack. By the time wolves are two years old, however, they leave the pack for good to find mates and territories of their own.
Not all the pups in a litter live to the age of dispersal, of course. Biologists have determined that only one or two of every five pups born live to the age of 10 months, and only about half of those remaining survive to the time when they would leave the pack and find their own mates. Adult wolves on the other hand, have fairly high rates of survival. A seven year old wolf is considered to be pretty old, and a maximum lifespan is about 16 years.
Wolves communicate through facial expressions and body postures, scent-marking, growls, barks, whimpers and howls. Howling can mean many things: a greeting, a rallying cry to gather the pack together or to get ready for a hunt, an advertisement of their presence to warn other wolves away from their territory, spontaneous play and bonding. There is no evidence, however, that wolves howl at the moon. Pups begin to howl at one month old. The howl of the wolf can be heard for up to six miles. When wolves in a pack communicate with each other, they use their entire bodies: expressions of the eyes and mouth, set of the ears, tail, head, and hackles, and general body posture combine to express excitement, anxiety, aggression, or acquiescence. Wolves also wrestle, rub cheeks and noses, nip, nuzzle, and lick each other. Wolves also leave "messages" for themselves and each other by urinating, defecating, or scratching the ground to leave scent marks. These marks can set the boundaries of territories, record trails, warn off other wolves, or help lone wolves find unoccupied territory. No one knows how wolves get all this information from smelling scent marks, but it is likely that wolves are very good at distinguishing between many similar odors.
Wolves prey mainly on large hoofed mammals (known as ungulates) such as deer, elk, moose, caribou, bison, bighorn sheep and muskoxen. They also eat smaller prey such as snowshoe hare, beaver, rabbits, opossums and rodents. Although some wolves occasionally prey on livestock, wild prey are by far their preferred food source.
Wolves have several different methods of hunting, depending on the size of the prey. For little tidbits such as mice, an individual wolf will listen for the squeaking and rustling under the leaves, and then pounce with her front paws when she pinpoints the direction of the sound. They will also eat birds, especially when the birds are molting their feathers and cannot fly well. Individual wolves will also chase hares or follow beaver trails to try to catch the animal away from the water. When hunting deer, pack members frequently all participate in the locating and stalking of prey. After that, anywhere from one to all of the wolves will engage in the chase. Larger prey animals, such as moose, caribou, and elk, don't always run when they encounter a pack of wolves. If the prey animal stands its ground, the wolves will often approach cautiously or abandon their pursuit after a few moments. When a prey animal does flee, the pack of wolves will chase them. Most healthy ungulates are fast enough to outrun a pack of wolves. In fact, fewer than one out of ten attempts to chase moose actually end in a successful kill. If they start to fall behind, the pack will usually give up the chase. If the chosen prey is injured, weakened, or old, however, the wolves can usually catch up with them and attack. Contrary to many popular accounts, wolves rarely, if ever, engage in "hamstringing," or biting the tendons on the back of the leg. This practice is simply too dangerous for the wolf, because to bite the leg, the wolves risk getting kicked in the face by the animal's sharp hooves. Wolves tend to concentrate on the neck, shoulders, and sides instead.
Wolves' digestive systems operate somewhat differently than ours. They are adapted to process huge amounts of food at a time, then eat nothing for three days or more. Biologist David Mech witnessed a pack of 15 wolves kill a 600- pound moose and eat about half of it in an hour and a half, meat, bones, fur and all. This works out to about 20 pounds of food per wolf! Mech estimated that the wolves he witnessed in this encounter were about 85 pounds each, which means they each ate about 23% of their body weight. They don't do much chewing, mostly just tearing chunks off and swallowing them whole. After eating their fill, wolves will either spend a few hours relaxing and digesting, or return to the den to regurgitate food for the pups and other pack members who did not join in the hunt. A wolf's digestive system can handle a large amount of food quickly and efficiently, processing the meat and fat so thoroughly that only bones and fur are excreted in the scat.
Wolves began to take on their distinctively large size about 15 million years ago, and looked like they do today by about 1 million years ago. Every breed of dog that we have today, from poodles to huskies, are descended from a small subspecies of wolf that was domesticated in China about 12,000 to 15,000 years ago.