Professor Tomback teaches in the Department of Integrative Biology at CU Denver. Her expertise includes evolutionary ecology, with application to forest ecology and conservation biology. She is a member of the science advisory board of several environmental organizations, including American Forests and the Rocky Mountain Wolf Project.

As a biologist, what is your view of the potential impact of reintroducing wolves to Colorado?

[Tombeck:] “Proposition 114 proposes to reintroduce wolves to the Western Slope of Colorado. The Western Slope comprises about 17 million acres of public lands and has low human density. There are several potential, pragmatic benefits from returning wolves to Colorado, where wolves have not had ecological influence for nearly a century. The last wolves in Colorado were extirpated in the late 1930s and 1940s.

“First of all, the reintroduction of gray wolves could help counter the spread of Chronic Wasting Disease (CWD) in deer and elk. CWD is prion-based fatal neurological disease, similar to Mad Cow Disease, that infects the deer family—deer, elk, and moose. Whether it can be transmitted to people is not known, but precautions should be taken. It was first found in Colorado in the 1980s. To date, CWD has been detected at varying incidence in more than half of Colorado’s deer herds and about 40% of our elk herds. The disease has spread across many states in the U.S. and Canadian provinces [see map below]. In fact, Colorado Parks and Wildlife urges head-testing for bucks before hunters and their families consume the meat. But wolves target weak prey and detect diseased animals, and many experts think that wolves could limit the spread of this CWD. The increasing incidence of this disease may be related to wolf extirpation.

“Other potential benefits from wolf reintroduction are similar to those we see in Yellowstone, where wolves reduced the elk population and changed their behavior, resulting in a trophic cascade of improvements to ecosystem health and a return of biodiversity. Many elk management units around Colorado have populations above target numbers established by Colorado Parks and Wildlife. Ranchers and farmers in some regions experience elk damage to their rangeland and crops and are compensated for this damage by the state. Elk also damage streamside vegetation, including willows and cottonwoods, and deer and elk browsing limit forest regeneration. A case in point is Rocky Mountain National Park, where miles of chain-link fencing were installed to reduce vegetation damage by an over-capacity elk population. In past decades, the park has lost its beavers and had its streamside communities greatly altered.” 

What about the interests of ranchers and hunters?

“We need to use science and data to reassure ranchers and hopefully dispel some long-held misperceptions. In the northern Rockies states—where there are now about 2,000 wolves and 1.6 million cattle—wolves prey on less than 0.01% of cattle annually. In these states, cattle outnumber elk about 4 to 1, but wolves prefer elk as prey. The small number of ranchers who have confirmed livestock losses to wolves deserve fair compensation, which Proposition 114 will provide. Many coexistence techniques and tools have been developed to reduce the likelihood of predation on livestock by carnivores in general (bears, mountain lions, coyotes, and wolves), and ranchers could benefit by adopting them. Approaches depend on circumstances, though, and include the installation of fences and fladry (flags that flap) to pen herds or flocks, carcass removal, patrols by range riders, guard dogs, and low-stress herding techniques to keep cattle together.

“Hunters worry that there will be fewer elk and deer available if wolves are reintroduced. But the numbers from the northern Rockies tell a different story: There are 30,000 more elk in Montana now than in 1995, when wolves were reintroduced, despite a current population of about 850 wolves. Elk numbers in Wyoming and Idaho are greater than state objectives. In all three northern Rockies states, hunter success and elk harvest have increased.”

Are there enough elk in Colorado for both hunters and wolves?

“The number of elk in Colorado, according to 2019 data from Colorado Parks and Wildlife, was nearly 300,000 post-hunt. Adding in the post-hunt mule deer population brings the total to more than 700,000 animals—far more than any other state in the lower 48. Furthermore, if wolves reduce the incidence of CWD, hunters will benefit.”

In addition to her expertise on wolves, Professor Tomback is a 2015 Harvard Forest Bullard Fellow known for her studies of Clark’s nutcracker, a bird of high mountain forests, and its interaction with several white pine species, particularly whitebark pine, leading to her election in 1994 as Fellow of the American Ornithologists’ Union.