Many big, wild animals are controversial, in part because they can bring large benefits to society, but also incur high costs. Often, the costs and benefits are not experienced by the same groups of people within society- for example, hunters and wildlife viewers benefit from large herbivores such as deer and elk, while farmers and ranchers may pay a cost due to lost crops or forage for domestic livestock. We are interested in how to better quantify both the costs and benefits of important wildlife species, and potentially how to equalize costs and benefits better across society, which could lead to greater tolerance for wildlife species in the human-dominated modern world.

Recently, we completed an analysis to examine one potential benefit of large carnivores, which is reduction of collisions between cars and large herbivores. This results in fewer deaths and injuries for drivers and passengers, and fewer costs due to healthcare, property damage, and lost productivity and quality of life. We plan to expand this work in the near future to examine the costs and benefits of large carnivores and herbivores.



How does herbivore density affect their costs and benefits to society, and subsequently, the costs and benefits of predators feeding on those herbivores?

Under what circumstances could predator benefits make people more willing to live with large carnivores?


Why answer this question?

Cougars, bears, wolves, coyotes, and meso-carnivores are recolonizing many areas of the United States, or changing their distributions, as populations make a come back after being protected from the heavy bounty hunting, trapping, and poisoning of much of the last 2 centuries and climate shifts. As a result, large carnivores are showing up in parts of the U.S. where they have not been in a very long time, with potentially important consequences for local economies and ecosystems through cascading effects.

One of the most important ways that we could benefit from colonizing carnivores is through reductions in over-abundant herbivores deer. For example, white-tailed deer cause billions of dollars of damage through deer-vehicle collisions and crop depredation annually, and also impact plant and animal abundance and biodiversity through heavy browsing.


How are we answering this question?

To begin to answer these questions, I worked with a team of ecologists (Dr. Laura Prugh, U Washington, and a number of graduate students at the U of Alaska Fairbanks) and an economist (Dr. Joseph Little, University of Alaska Fairbanks).

We developed a density-dependent population model for white-tailed deer based on multiple field-based research studies, and simulated the addition of cougars to this system. Then, using economic data on the rate of deer-vehicle collisions (such as collisions per mile driven, $ per collision, and injuries and fatalities per collision), we evaluated the potential savings in dollars, and preventions of human deaths and injuries from deer-vehicle collisions, thanks to cougar recolonization.

We also used existing, real-world data from an area of the country where cougars have recently recolonized, South Dakota, to ask this same question empirically.

In the future, I and my research group would like to expand this work to include other species and ecosystems with other costs and benefits, and to collect additional empirical data to test our theoretical predictions.