Spotlight on Research: Mason Researchers Track Coyotes Close to Home
Posted: November 11, 2004 at 1:00 am, Last Updated: November 30, -0001 at 12:00 am
By Lynn Burke
Recent coyote sightings within the Capital Beltway have come as a surprise to many. But to George Mason professor Larry Rockwood, Environmental Science and Policy, and his team of graduate student researchers, the news isn’t all that surprising. Rockwood, Kristi Robinson, Christine Bozarth, and Megan Draheim have been studying coyotes since 2001 as close as Quantico Marine Base, just 36 miles south of Washington, D.C.
“Coyotes, a species that started colonizing [Quantico] in about the early 1990s, are now distributed throughout much of the base,” says Robinson. “They are still relatively elusive there and in the D.C. metro area in general; however, in the past few years, sightings of them have become more common. This may be due to their increasing population, increased security of this species in the habitat and area, or both.”
The team’s work is supported by the Department of Defense’s Legacy Resource Management Program. Working with Tim Stamps, head of the Fish/Wildlife and Agronomy Section of Quantico’s Natural Resources and Environmental Affairs Branch, the team is helping to determine the distribution of coyotes and other members of the Canidae family (canids) on the base, which will help its natural resource managers incorporate the data on the animals in their ecosystem and wildlife management plans.
“The military realizes that their bases have become de facto wildlife preserves because there aren’t many suburban areas left where you can have an unbroken expanse of land that forms a big complete ecosystem,” says Robinson. “Quantico, for instance, is between 65,000 and 68,000 acres.” Rockwood adds that because the base partially abuts Prince William Forest Park, wildlife have a large area in which to travel.
The first evidence of coyotes at Quantico came in the form of road kill, the discovery of which alarmed deer hunters who are allowed on the base. They were afraid the coyotes would diminish the base’s deer population. At the time, Robinson was there helping out with a study of freshwater otters by Michael Brandhagen, another Mason graduate student. Because she was looking for a project at the time, Robinson found the coyotes’ presence to be good news. Rockwood proposed a research project on the seasonal feeding habits of coyotes, and they were able to secure a grant for the study. The project has since expanded to cover other canids on the base: red fox and gray fox.
To determine the canids’ diet, Robinson collects their scat (feces). She promises it is not as unpleasant a task as it may sound. “It’s much easier on the researchers and much easier on the animals [than other methods of dietary analysis],” she says.
Rockwood cites the example of Branhagen and Mary Cogliano, another Mason otter researcher, to illustrate why scat collection is more effective. Cogliano spent more than three years trying to trap otters. “She finally trapped four or five total-one of which bit her and got away, and one of which died immediately after she put a transmitter on it. For all that effort (including getting a rabies shot), she had only two or three animals from which she gathered data.”
In contrast, Brandhagen, who used scat analysis for his otter project, was able to identify 23 different otter individuals and plot a bit of their home ranges. “He never had to trap a single animal—or get bitten,” says Rockwood.
Robinson collects the canid scat herself and says that it is relatively easy to find. “To a large extent, the animals conveniently deposit their scat in roadways.” She has various transects of the base mapped out and records where she finds the scat. Before she heads out, though, she must first check in with the base’s range control to see where the marines are firing that day. Certain parts of the base are off limits because of range activity or the presence of unexploded ordnance.
After only a few years of work, the team has made some preliminary findings:
- All three species will share the same territory and the same paths within that territory; however, there is temporal partitioning.
- As coyotes become more established within a given area within the base, the incidence of seeing evidence of foxes decreases in that area.
- There is evidence of more gray foxes (a native species) than red foxes (an introduced species) at Quantico, which seems to be the opposite of what is found in more urban areas.
As for the animals’ diet, the team has found that all species transition to a higher proportion of small mammals in their diet as late fall and winter progresses. In addition, gray foxes can climb trees to some degree, so they are more likely to have more fruit in their diet and are therefore the most highly vegetarian of the three.
Bozarth is performing the molecular work of the research, using fragment analysis of the DNA extracted from the scat to identify the canid. “There’s a certain section of DNA that we can isolate, and its length is different in different species,” says Bozarth. “So instead of sequencing the entire piece of DNA, we can just look at the fragment length to determine the species.” She hopes eventually to identify individual canids through their DNA as was done in the otter research. Bozarth is working with Jesus Maldonado, a research geneticist at the Smithsonian’s Genetics Program in the National Museum of Natural History’s Department of Systematic Biology, and Patrick Gillevet, associate professor of Environmental Science and Policy at Mason.
Draheim is also working to identify canids by their scat, but hers is a low-tech method. She is training dogs to scent-identify scat by species. She hopes to train the dogs to a point where the DNA analysis can be skipped completely or used on a limited basis. She cites as a precedent work by a woman who has trained dogs to identify individual tigers in Russia, and notes that dogs have been used in studies of grizzly bears, black bears, kit foxes, and tortoises. Sue Hunter, a trainer at the National Aquarium in Baltimore, is a consultant on this part of the project.
Right now, Draheim is working with her own two dogs, a beagle mix and pit bull mix, on their coyote and red fox discrimination. She hopes to improve upon the methods in which dogs are trained for this kind of work. She says that most people doing this sort of work have backgrounds in training dogs to detect narcotics and use positive and aversive training methods with specific types of dogs. Her idea is to train random dogs (which are less expensive than specially bred dogs) using only positive reinforcement. If successful, she believes these dogs could be a useful tool for underfunded projects in remote locations.
And as for the hunters’ fears that the coyotes would ruin deer season, the team says that’s not a concern because coyotes, which for the most part are solitary creatures, aren’t going to go after anything bigger than themselves.
“Coyotes are opportunists,” says Robinson. “Like any wild animal, they are not going to risk hurting themselves unnecessarily. In this climate, there are plenty of small prey available year round and tons of vegetation for them to eat during most of the year. Why risk hurting themselves on a big deer?”
For more information on coyotes, visit the Animal Protection Institute web site.