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The Big Bad Wolf isn’t so Big Anymore

Don't bring a wolf to a gun fight. How bad PR nearly drove the Gray Wolf to extinction

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How are the St. Louis Arch and the ecosystem in Yellowstone similar? Although these two things seem like opposites—one a monument to the success of a booming metropolis, the other a wild realm essentially untouched by human activity—they both require a critical thing to stay standing, a keystone. A literal keystone at the apex of the St. Louis arch prevents it from collapsing, and a figurative keystone species at the apex of the food chain in Yellowstone prevents the ecosystem from collapsing.

Wolves, the keystone species in Yellowstone, have a reputation as being ruthless killers who will stop at nothing to get a meal.  For instance, in fables like Little Red Riding Hood, Three Little Pigs, and Peter and the Wolf, wolves are portrayed as savage beasts who will stop at nothing to get a meal; the only animal that people regard as less favorable than a wolf is a skunk, and these fables further concrete this feeling of antipathy1. So, because of this reputation, wolves are easy to vilify. However, upon rumination, they are the victim; victims from when humans tried to tame the proverbial ‘Wild West’. When humans took to settling in the western United States in the 1900’s, they ravaged the wolves’ food sources—deer, bison, elk. With their traditional meals depleted, wolves were forced to feed upon livestock, soon becoming enemies to ranchers and cowboys.

When Yellowstone National Park was dedicated in the late 1800’s, approximately 300-400 gray wolves were living across its expanse2. To preemptively defend the ranchers’ livestock from wolf attacks, the government started eradicating gray wolf populations, not only in Yellowstone but across the entirety of the contiguous United States3. Government-issued bounties of $50 (adjusted for inflation: $400) were offered to anyone who killed a wolf up until 19653-4. People were uprooting wolves from their dens, hunting them with dogs, and even killing them with poison gas3. This pogrom was so heavy-handed that by 1924 the remaining two wolf pups left in Yellowstone were killed and by 1930, wolves were practically extinct from the United States besides for populations left in Alaska2. This widespread extermination ushered in a 7-decade long period of complete wolf absence in Yellowstone.

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Following the exterminations, only a few, highly-isolated enclaves were left in the contiguous United States5. This severe fragmentation and prevention of gene flow caused a bottleneck effect; and random killings by hunters killed the most voracious and fittest wolves, leaving only the runts of the packs as the sole survivors5. This small population size coupled with an unfit population of wolves meant inbreeding became common, litters were often plagued with congenital genetic diseases, and each subsequent generation was less fit than the last. With each new generation of wolf in these fragmented populations, the overall fitness decreased until smaller predators like coyotes were soon able to outcompete the remaining wolves for the food sources they had once had complete dominion over—deer, bison, elk5.

The severe loss in healthy wolf populations sent noticeable reverberations throughout cascading trophic levels: The herbaceous ungulates that once fell prey to wolves experienced a population boom. However, this relatively spontaneous growth of ungulates is detrimental to many other populations. For instance, oak trees were once plentiful in Yellowstone. They used their acorns to spread their seeds and mutualistic root fungi (mycorrhizae) through mice vectors7. However, when the boom of ungulates occurred, oak tree populations were devastated and the oak tree, mouse and fungi species went extinct in Yellowstone7.

Furthermore, increased and heavy browsing by deer populations put many plant species at risk, not just in Yellowstone but the entire United States. In many places, specifically the Midwest, the understory contains many plants and herbs that ungulates eat preferentially yet these plants are also intolerant to grazing7. The seedlings and saplings of slow-growing coniferous softwoods such as hemlocks and cedars are especially vulnerable since most are eaten by deer before sprouting beyond 1 foot (30 cm)7. This change in genetic diversity means that only a few types of plants can thrive in this new environment: ferns and grasses which deter deer by chemical or physical means, usually via thorns or allelopathy, or shrubs that tolerate grazing via rapid growth and have subterranean meristematic tissues and rhizomes for growing and proliferating below ground7. The increased grazing indirectly causes reduced amounts of pollinators, songbirds, and invertebrates that depend on now receding forest flora7.

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Image from Pexels

After realizing the adverse effects that over 70 years of gray wolf absence had on local flora and fauna, the United States government provided grants to researchers who were willing to monitor and reintroduce gray wolf populations in Yellowstone. Since most wolf populations in the contiguous United States were infirm, researchers probed healthy Alaskan population and tagged and transported them to Yellowstone8. After 15 years, the gray wolf populations remained healthy, wild coyotes and ungulate populations declined, and plants like aspens and oaks started to repopulate the landscape8.

Despite successful reintroduction, it is essential to keep the current gray wolf population from declining; since wolves can migrate 100 kilometers every year, it can be hard to keep transplanted wolves on protected lands10. When wolves wander off of protected lands, they may make enemies with hunters or livestock ranchers by killing their game or livestock. Although it is difficult to protect hunters’ game, protecting commercial livestock from wolves has many promising solutions. The most popular and cost-effective being livestock guarding animals9. The best animals for the job are dogs since they are usually large, independent, intelligent, attentive and gentle towards livestock, but aggressive towards predators9. The dog is placed in the flock of livestock at birth, allowing time for the pup to build long-lasting familial relationships with the livestock9. Interestingly enough, other animals such as llamas can also be used instead of dogs to deter wolves and coyotes9.

Despite possible problems with wolf migration, the approximately 100 wolves in Yellowstone are healthy, and their introduction surpassed many ecological projections with many species of plants returning to Yellowstone10. Although it may be easy to vilify certain animals, it is important to understand how they affect the ecosystem they live in. This notion is especially difficult because humans are hardwired for quick fight-or-flight responses– tackling slow-moving and abstract problems can be very difficult. Hopefully, this experience will be able to help conservation efforts from exterminating species that have strong direct or indirect effects on other wildlife.


Works Cited:

[1] Kellert, Stephen R. “Public Perceptions of Predators, Particularly the Wolf and Coyote.” Biological Conservation, vol. 31, no. 2, 1985, pp. 167–189.

[2] “The Yellowstone Wolf: A Guide and Sourcebook”.  Yellowstone Association.  1996

[3] Wagner, Stephen C. “Keystone Species.” Nature, 2010, http://www.nature.com/scitable/knowledge/library/keystone-species-15786127.

[4] “CPI Inflation Calculator.” U.S. Bureau of Labor Statistics, http://www.bls.gov/data/inflation_calculator.htm.

[5] Wayne, Robert K., et al. “Mitochondrial DNA Variability of the Gray Wolf: Genetic Consequences of Population Decline and Habitat Fragmentation.” Conservation Biology, vol. 6, no. 4, 1992, pp. 559–569.

[6] Kellert, Stephen R. “Public Perceptions of Predators, Particularly the Wolf and Coyote.” Biological Conservation, vol. 31, no. 2, 1985, pp. 167–189.

[7] Strong, D.R., Frank, K.T., “Human involvement in food webs”. Annual Review of Environment and Resources, vol. 35, 2010, pp. 1-23

[8] Ripple, William, and Robert Beschta. “Trophic Cascades in Yellowstone: The First 15 Years after Wolf Reintroduction.” Biological Conservation, vol. 145, 2011, pp. 203–213.

[9] Sillero-Zubiri, C., J. Reynolds, and A. J. Novaro. “Management and control of wild canids alongside people”. Oxford University Press, 2004, pp. 123-142.

[10] Mech, L.D., “Age, season, distance, direction, and social aspects of wolf dispersal from a Minnesota pack”. University of Chicago Press, 1987, pp. 55-74

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