By Jaymi Heimbuch
Coyotes live in practically every city in the United States, yet the vast majority of human residents never spot a single one. That’s because urban coyotes are skilled at steering well clear of humans, even switching to nocturnal behavior just to stay out of sight.
So what makes some coyotes more likely to be active during the day, or hang around in areas closer to humans with a higher chance of having a run-in? Are these animals simply more bold and brazen, destined to become problem animals — or is there more to it?
We were really interested in the question of why certain individuals are much more likely to be encountering people when really most [urban] coyotes avoid people, tend to stick with natural areas, tend to be quite nocturnal. We wanted to know why there are these big differences in behavior across coyotes.
A study published earlier this spring in Proceedings of the Royal Society B helps answer this core question about urban coyotes. Maureen Murray of the Edmonton Urban Coyote Project and her team caught and collared 19 coyotes. Using GPS location data from the collars, hair samples collected while collaring, and video footage placed around nine compost piles, the researchers discovered that these very compost piles and a common disease called sarcoptic mange are two key factors in causing coyotes to alter their behavior and potentially be involved in more human-coyote conflicts.
When the team collared the coyotes, they noted their general health including whether or not they had signs of mange. As they collected GPS collar location data, they noticed distinct differences. The individuals with mange had not just slightly different behavior, but distinctly different behaviors and habits than those individuals without the disease.
Mange is a highly contagious skin disease caused by a mite. It is commonly found in animal species, including our own domestic dogs. The mites burrow just under the skin, causing extreme itching and discomfort as well as hair loss. Imagine the feeling of a constant, pervasive itch and a desperate need to scratch, to the point that you injure your own skin and have trouble concentrating on anything else including eating. Imagine also that the itch causes your hair to fall out, leaving you vulnerable to the cold. That is what an animal with mange is experiencing. So it is no surprise that those individuals with mange would have different behaviors. But the extent to which it affects them is of interest.
“The guys with mange had these huge home ranges, like 60 square kilometers,” says Murray. On the other hand, “the healthy ones never really leave the natural areas. As our sample got bigger and bigger, this pattern kept holding that the ones with mange weren’t nocturnal like the healthy guys. They were active pretty equally at all times of day, they used residential developed areas five times more often, and they had four times larger home ranges.” In other words, the coyotes with mange travel much more, in areas and at times of days where they are much more likely to encounter people. But that isn’t the only important distinction.
The coyotes with mange also tended to use residential back yards, specifically those with compost piles. The lure of the compost pile is a key piece of the puzzle in behavior differences among coyotes, but the reasons why are complex.
The team wanted to discover if the compost piles aggregate coyotes, attracting sick coyotes and healthy coyotes alike, and perhaps assisting in the spread of mange among these urban animals. To find out the answer, the team put cameras on the compost piles and looked at how often a coyote with hair loss — a sure sign of mange — appeared and how far apart the visits of individual coyotes were spaced.
With the help of the remote cameras, Murray found that coyotes with hair loss were recorded at compost piles more frequently than they were recorded on cameras set up in natural areas. Not only that, but the visits to compost piles by different coyotes were much closer together in time, increasing the chances of healthy coyotes coming into contact with disease.
Coyotes are naturally territorial so healthy coyotes hunting for rodents and small prey in their home range are sure to let visiting coyotes know they aren’t very welcome on their turf. In normal wild situations, the chances of many coyotes meeting up often enough to spread mange are much, much lower. But when you throw in a steady supply of food provided by humans, the dynamics shift. In short, the compost piles are bringing coyotes together far more frequently than happens in natural areas, and more of those coyotes are sick.
The team found that the difference between healthy and sick coyotes isn’t just in where they roam and when. It also comes down to the specific foods they’re eating and how their diet is affecting their overall health.