During March 2012, Denali park biologists noticed an increase in coyote abundance at a time when the population of wolves was decreasing. Increased coyote abundance throughout North America may be connected to the extirpation of wolves. If so, it is likely an example of “mesocarnivore release,” which is the expansion in range and/or abundance of a smaller carnivore (“mesocarnivore”) following the reduction or removal of a larger predator. These effects can extend beyond small carnivores to include their prey. For example, studies in Alaska have shown that high coyote populations in areas where wolves are scarce can reduce the survival of Dall sheep lambs. Since wolves often kill coyotes, the presence of wolves might limit coyote abundance. However, wolves also support coyotes by providing food in the form of ungulate carrion, so the net effect of wolves on coyote populations is hard to determine. In northern ecosystems, coyote populations fluctuate with changes in abundance of their primary prey (snowshoe hares and voles). Population cycles of these small mammals could influence the degree to which coyotes rely on wolf-supplied carrion, which would change the dynamics of the relationship between coyotes and wolves. Furthermore, competition between coyotes and other mesocarnivores is thought to be influenced by habitat characteristics, such as snow depth and density, which are changing in response to long-term changes in climate.
Mid-Sized Carnivores in Denali
In the summer of 2012, Dr. Laura Prugh of the University of Washington started a study to determine which are the most important factors controlling coyote populations in the park. Is it suppression by wolves? Availability of prey? Habitat characteristics like snow? This information can be used to determine the strength of mesocarnivore release of coyotes and resulting effects on the mesocarnivore community. These relationships are investigated in a variety of ways:
- Winter track surveys can be used to assess abundance and distribution of wolves, coyotes, red fox, lynx, wolverine, and marten in relation to prey abundance, habitat type, and snow conditions.
- Carnivore scats are collected which can be used to assess dietary overlap among carnivores. They can also be used to estimate abundance of coyotes and foxes using DNA mark-recapture techniques.
- Radio-collaring coyotes allow researchers to compare the movements of wolves and coyotes to determine how the two species divide the available habitat.
The study is a collaborative effort between the University of Washington and Denali National Park and Preserve. In addition to providing increased understanding of the relationships among these species, this project will provide park managers with improved techniques for assessing and monitoring important furbearer species that have received little attention in the past.
M.S. candidate Kaija Klauder is continuing the winter and summer long-term data collection. Her thesis will center on examining the behavior dynamics of scavenging carnivores at kill sites, quantifying wolf revisitation rates to their kill sites, and analyzing movement data from the collared animals.
During 2013-2015, a total of 9 coyotes were captured and radio-collared with GPS-equipped collars. Snow track surveys were conducted during the winters of 2012-2013 and 2014-2015 on trail systems within the park, in the Stampede corridor, and in the upper Susitna drainage. Data from the first two years of the study continue to be analyzed and formed the basis of Kelly Sivy’s and Casey Pozzanghera’s M.S. theses through University of Alaska Fairbanks, completed summer 2015.