The Gray Wolf (Canis lupus)
FROM MYTH & LEGEND TO MAINTAINING ECOSYSTEM HEALTH
ECOLOGY OF THE GRAY WOLF (CANIS LUPUS)
The gray wolf is the largest species in the Canidae family, which includes dogs, wolves, coyotes, jackals, and foxes. The fossil history leading to the gray wolf’s origin tells a long and complex story of extinction and survival. The earliest fossil records of the gray wolf first appeared before the end of the Pleistocene. Many species of wolves rose and fell before the Pleistocene yielded to our own era, the Holocene, around twelve thousand years ago (Derr, 2011). The gray wolf emerged during a period of rapid environmental change and glacial activity that resulted in diminishing species diversity.
The gray wolf has one of the greatest natural ranges of any living terrestrial mammal (Nowak, 1999). Their widespread success in many ecosystems around the world may be due to certain evolutionary adaptations. For example, wolves display behaviors that are rare among large carnivores: they run and attack together, they are constantly aware of the position of everyone in the pack, spatially and temporally; they communicate over distances and act in concert, and they adapt their hunting style to suit their prey (Derr, 2011). These adaptations have made it easier for the wolf to inhabit most of the ecosystems in the Northern Hemisphere (Derr, 2011; Nowak, 1999). Between 36-40 subspecies of the gray wolf are dispersed around the world (Wikipedia, 2015). Unfortunately, some are also now extinct (Eisenberg, 2014).
Gray wolves are most often found in packs consisting of an adult pair and their offspring. The leader is normally the male who initiates activity, guides movements, and makes decisions. Males and females have distinct dominance hierarchies within the pack and only the most dominant pair mate. Depending on pack dynamics, subordinate but sexually mature wolves may leave their natal pack to find mates and establish new packs. Young wolves are whelped in the spring and reared in dens in rock crevices, hollow logs, overturned stumps, or burrows near water (Nowak, 1999). When the young become mobile, they move to rendezvous sites where their parents and other pack mates bring them food. Late in the fall they begin to join adults on hunts.
Although wolves can show significant geographic polymorphism (Wikipedia, 2015), the basic physical appearance of the gray wolf is much the same today as it was several thousand years ago. They have a lithe, muscular, deep-chested body, long slender limbs, a bushy tail, a long slender muzzle, yellowish-white colored legs, and large erect ears. While their fur is usually long and light brown to gray with sprinkles of black, some populations or individuals display coats of all black or all white. Their head and body lengths range from 39 to 63 inches (99-160 cm) with the tail ranging from 13 to 22 inches (33-55 cm). On average, males are larger than females. Weight ranges from 44-176 pounds (19-79 kg) for males and 39-121 pounds (17-55 kg) for females (Nowak, 1999). Lifespan ranges from 10-16 years (Nowak, 1999; Young and Jackson, 1978). Various environmental and genetic factors account for the differences in size, weight, and lifespans among subspecies. Gray wolves have four digits on the hind foot and five digits on the forefoot. Wolves walk only on their toes (Nowak, 1999).
The gray wolf is predominately a predator of mammals larger than itself (Nowak, 1999), specializing on ungulates (hoofed mammals). Typical prey include deer, elk, caribou, bison, moose, muskox, and mountain sheep. A highly-developed sense of smell and sight aids them while hunting. Wolves use several different strategies to find their prey: chance encounters, direct scenting, or following a fresh scent trail. During hard times wolves will eat beaver which are one of their smallest but most consistent food sources. Prey are usually captured through a strategy of stalking as closely as possible to the intended target and then giving chase. While the average walking speed of a gray wolf is 4 miles per hour (6.4 kph), the running gait is between 34 and 43 miles per hour (54.7-69.2 kph). Most often, if a prey animal is not caught quickly, or is large and healthy and turns to confront the pack, the pack will give up the chase (Nowak, 1999).
Since wolves are an apex predator, they experience little to no mortality from other species in their natural environment. In some instances, wolves kill each other during territorial disputes and conflicts within and between packs. However, most wolf mortality comes from humans and their activities. Habitat fragmentation and urban sprawl have played a pivotal role in the conflict between humans and wolves. Influences on gray wolf habitat and mortality include: habitat conversion for human uses, inadequate regulatory protections, authorized human hunting and trapping, illegal killing, killing or removal in response to conflicts with livestock production in wolf habitat, fluctuations in primary prey populations; insufficient or ineffective law enforcement, and disease. These factors have affected wolf populations locally and globally by destroying habitat, creating barriers to dispersal and migration between habitats, and reducing prey populations upon which wolves depend.
EVENTS LEADING TO THE CURRENT STATE OF GLOBAL GRAY WOLF POPULATIONS
(Cohn, 2011; Lute, et al, 2014; Nowak, 1999; USFWS, 2015; Young & Jackson, 1978):
- Increased pressure on global ecosystems, mass consumption of raw materials, pollution and habitat destruction, all begin to take shape as human population centers shift, grow, and migrate to meet the demands of modern society;
- Widespread government bounties for large carnivores in North America begin as people move westward;
- Last wolves in the British Isles are exterminated.
- Wolves are eliminated along the east coast and Ohio Valley of the United States;
- 1860-1885, widespread use of poisons such as strychnine becomes popular and are utilized extensively throughout North America on large carnivores to eradicate perceived threats to people and livestock.
- Last wolves are eradicated in Canada south of the St. Lawrence River and the eastern U.S. except for Minnesota
- Wolves disappear from Western Europe and Japan;
- In the former Soviet Union, populations decline from 200,000 individuals to 50,000 following an intensive government eradication program;
- Wolves are exterminated in the western U.S. and Mexico;
- Large scale aerial hunting becomes popular across the globe;
- 1973-1974, Endangered Species Act provides regulatory protection for gray wolves making their recovery possible in the U.S.;
- 1988, wolf reintroduction program planning begins in U.S.;
- 1995, wolves are reintroduced into Yellowstone National Park, Wyoming, and Idaho;
- 1998, Mexican gray wolves are reintroduced in the Apache and Gila National Forest in Arizona and Mexico.
- 2011-2012, U.S. Congress and USFWS delists Gray Wolves from Endangered Species Protection in the Northern Rockies allowing renewed hunting;
- 2012-2013, federal wolf management authority is largely turned over to state agencies.
ECOLOGICAL ROLE OF WOLVES
As with many large carnivores, wolves play a positive role in maintaining ecosystem health and integrity. Through a phenomenon called trophic cascade, wolves are a keystone species with many plants and animals depending on the wolf’s function in the food web (Licht, et al, 2010).
For example, one study in a Canadian national park noted the negative effect of wolf exclusion by humans on various native species that might not otherwise be viewed as mutually dependent on each other. Researchers discovered that wolf exclusion decreased aspen recruitment, willow production, and increased willow and aspen browsing intensity. Beaver lodge density was negatively correlated to elk density, and elk browsing had an indirect negative effect on riparian songbird diversity and abundance (Hebblewhite, et al, 2005).
Another study notes that due to the absence of wolves, ungulates threaten vegetation health across large portions of the United States. In contrast, the presence of wolves increases plant biomass and diversity. Scientists also argue that retaining wolves as part of good stewardship programs are win-win for everyone. For instance wolves had a beneficial economic impact on Yellowstone National Park, which saw increased visitation and ecotourism spending of $35 million in 2005 (Licht, et al, 2010).
TIPS AND TOOLS FOR COEXISTENCE
Wolves’ predation on livestock is a source of controversy that has led to the institution of lethal means to address this conflict. However, recent advances in technology and new models of integrated ranching methods have given wolves a renewed chance of survival by offering non-lethal means to deter interactions, reduce livestock mortality and promote coexistence.
Scientists concerned with the welfare of wolves often monitor den sites and pack movements through radio-collar telemetry and remote camera data. This valuable technology allows ranchers to be notified when wolves are occupying a particular area and to rotate livestock (Eisenberg 2014) (LWW, 2015).
In addition, various repellents are available that disrupt predatory behaviors by using chemical, visual, and/or auditory distractions that induce wolves to stay away (Shivek, et al, 2003). Other measures include wolf translocation (Bradley, et al, 2005), removal of dead, sick, and diseased livestock where carcasses might be easily scavenged by wolves, the use of trained guard dogs and night watchmen (LWW, 2015), shed lambing and night penning (Shivik, 2006), range riders, noise making devices called rag boxes, and electric fencing (Eisenberg, 2014).
Furthermore, exclusion systems are often used in the form of “turbo fladry.” This is a combination of an ancient Eastern European technique that deploys a long string with hanging colorful flags and modern technology (above-ground electrified wires) to prevent wildlife from attacking livestock. When properly installed and maintained electrically charged perimeters with fladry can keep domestic animals safe inside a defined area by keeping potential predators out (Shivik, 2006). Coexistence between humans and wolves presents many challenges requiring changes in long-held beliefs, values, and practices with regard to livestock production in wolf-occupied areas. Many resources and organizations now exist to educate and assist livestock owners with evolving techniques that will keep their sheep and cattle safe by using predator-friendly management tools that deter attacks.
Bradley, E.H., Pletscher, D.H., Bangs, E.E., Kunkel, K.E., Smith, D.W., Mack, C.M., Meier, T.J., Fontaine, J.A., Carter, C.N., Jimenez, M.D. (2005). Evaluating Wolf Translocation as a Nonlethal Method to Reduce Livestock Conflicts in the Northwestern United States. Conservation Biology 19(5), 1498-1508
Cohn, J.P. (2011). Wildlife Groups Opposing Congressional Delisting of Gray Wolf. Bioscience, 61(8)
Derr, M. (2011). How The Dog Became The Dog: From Wolves To Our Best Friends. New York: Overlook Duckworth.
Eisenberg, C. (2014). The Carnivore Way: Coexisting With and Conserving North America’s Predators. Washington: Island Press.
Hebblewhite, M., White, C.A., Nietvelt, C.G., McKenzie, J.A., Hurd, T.E., Fryxell, J.M., Bayley, S.E., Paquet, P.C. (2005). Human Activity Mediates a Trophic Cascade Caused by Wolves. Ecology, 86 (8), 2135-2144
HOME: LWW – Living with Wolves. (n.d.). Retrieved April 12, 2015, from https://livingwithwolves.org/
Licht, D.S., Millspaugh, J.J.,Kunkel, K.E., Kochanny C.O., Peterson, R.O. (2010). Using Small Populations of Wolves for Ecosystem Restoration and Stewardship. BioScience, 60 (2).
Lute, M.L., Bump, A., Gore, M.L. (2014). Identity-Driven Differences in Stakeholder Concerns About Hunting Wolves. Public Library of Science (PLoS) One, 10 (1371)
Northeast Wolf Coalition. (n.d.). Retrieved April 12, 2015, from http://www.northeastwolf.org/
Nowak, R. (1999). Walker’s Mammals Of The World (6th ed.). Baltimore: Johns Hopkins University Press.
Shivik, J.A., (2006). Tools for the Edge: What’s New for Conserving Carnivores. BioScience, 56 (3), 253-259.
Shivik, J.A., Treves, A., Callahan, P. (2003). Nonlethal Techniques for Managing Predation: Primary and Secondary Repellents. Conservation Biology, 17 (6), 1531-1537. Subspecies of Canis lupus. (n.d.). Retrieved April 10, 2015, from http://en.wikipedia.or/wiki/Subspecies_of_Canis_lupus
Western Gray Wolf: U.S. Fish and Wildlife Service. (n.d.). Retrieved April 12, 2015, from http://www.fws.gov/mountain-prairie/species/mammals/wolf
Young, S., & Jackson, H. (1978). The Clever Coyote. Lincoln: University of Nebraska Press.
Written by Nicholas Franz