Wild animals are often immersed in a mortal struggle. For white-tailed deer fawns, the struggle entails hiding from predators like coyotes.
“Fawns are highly vulnerable to coyote predation,” says John Kilgo. Kilgo is a research wildlife biologist at the U.S. Forest Service, and he recently coauthored a study about coyotes, fawns, and land cover.
Coyotes and white-tailed deer have not always lived in southeastern forests together. Coyotes began migrating from the western U.S. sometime in the 20th century. In South Carolina where the study took place, the predators moved in just a few decades ago, in the 1980s.
In many areas, coyote predation has diminished deer populations. States have tried to protect deer by limiting the number of does and young bucks – antlerless deer – that hunters can harvest. Some states have also killed coyotes to prevent them from killing deer.
Kilgo and William Gulsby, an assistant professor at Auburn University, recently investigated the effects of land cover on fawn predation risk. Gulsby led the study which was published in The Journal of Wildlife Management.
Gulsby, Kilgo, and their co-authors used a six-year dataset that Kilgo and others had collected. The scientists tracked fawns – 216 total – from 2007 to 2012 and recorded their movements and causes of death. “We monitored the fawns every 8 hours until they were about a month old,” says Kilgo. “After that, we monitored them 1 to 3 times a day until they were about 3 months old.”
The study took place on the U.S. Department of Energy’s Savannah River Site in South Carolina. The nuclear reservation covers 310 square miles, and more than 90 percent of the reservation is forested and actively managed. Forests are managed for long rotation lengths – up to 120 years. “The long rotation length and the large scale of forest management is somewhat uncommon in the southeastern U.S.,” says Kilgo. “Our results may be less applicable to sites with different management practices.”
However, the study strongly suggests that fawn survival is linked to edge habitat. Edge habitat refers to areas where two land cover types join.
“For reasons that we don’t fully understand, fawns whose home ranges have relatively high amounts of edge habitat are more likely to survive,” says Kilgo. “Fawns with the least amount of edge in their home range were more than twice as likely to be killed by coyotes as those with the most edge.”
The results can also show where fawns are most at risk. “We can evaluate land cover across large spatial scales and show where forests are homogeneous,” says Kilgo. “Where feasible, if managers can treat these areas to create heterogeneity, fawns should benefit.”
Fawns whose home range had many small patches of different cover type had the best chances of survival. The researchers were uncertain whether this was because the edge areas provided better hiding spots, or whether there were simply too many areas for coyotes to search. However, the findings are consistent with results from the Midwestern U.S., despite differences between the regions.
“Coyotes are in the southeast to stay,” says Kilgo. “They will likely prey on white-tailed deer fawns for the foreseeable future.” Coyote control is sometimes impractical or ineffective and limiting doe harvest remains the best management tool to increase deer numbers. However, where possible, managing forests to create diverse stand types and ages could help fawns survive, while also helping improve overall habitat quality for white-tailed deer.
Read the full text of the article.
For more information, email John Kilgo at jkilgo@fs.fed.us.