Environmental Almanac: An adaptable carnivore
On a cold, bright morning at the end of December, I was driving to Norris Tire and Auto in Champaign when I spotted a red fox trotting in the opposite direction, just off Springer Drive. I whipped the car around to try for photos as the fox negotiated a couple of parking lots, crossed Mattis Avenue (whew!) and then disappeared behind a pile of construction rubble.
When I arrived at the shop a short time later, I found people there had gotten good looks at the fox, too, and Mr. Norris was explaining why we see more foxes in town now than we used to.
He referred to a study conducted by a University of Illinois doctoral student in the Department of Natural Resources and Environmental Sciences, which looked at movements and mortality among 335 foxes that were fitted with radio collars between 1996 and 2002.
According to that study, red foxes declined in rural parts of East Central Illinois over the last three decades of the 20th century as farming became more intensive (which reduced the amount of prey available by reducing cover) and coyote populations grew (because coyotes kill foxes).
At the same time, the study found, foxes thrived in urban areas, where coyotes are scarce and rabbits are more abundant.
That's not to say life is ever easy for foxes. Fewer than one in four of the fox pups in the study survived through its first year, and only one in three adults made it through an average year. (Although urban foxes are safer from coyotes than their rural counterparts, they are much more susceptible to sarcoptic mange, a fatal infectious disease caused by mites.)
With such high mortality, foxes persist by reproducing at a high rate; females often breed in their first winter, and litters range from four to 10 or more.
Why do people get so excited about seeing foxes? Ed Heske, who specializes in mammal ecology at the Illinois Natural History Survey, a division of the UI Prairie Research Institute, credits the in-between space they occupy from a human perspective. "They're cool because they're wild carnivores, but they're small enough not to be threatening."
Indeed, even though its full coat and bushy tail can make it appear larger, an adult red fox typically weighs only somewhere between 8 and 13 pounds — less than some housecats I know.
Foxes may not possess all of the cunning or wisdom attributed to them by folklore, but they are pretty amazing. Have you ever seen video of a fox pouncing to catch a small mammal — or, better still, seen that yourself?
Scientists know foxes are especially sensitive to the low-frequency sounds made by prey animals as they move about or chew. But research conducted recently in the Czech Republic suggests foxes may also possess a magnetic sense that helps them estimate distance. The possession of such a sense would go a long way in explaining how a fox can leap into the air and punch through the snow to pin a mouse without having seen it.
I think my own fondness for red foxes owes to their adaptability. They occur throughout the Northern Hemisphere, and they occupy an incredible range of habitats, from cities and farms, to forests, grasslands, mountains and deserts. They can den under a shed or pass through your backyard at night without attracting notice. They eat rabbits and other small mammals for the bulk of their diet, but they also take advantage of insects and fruit when those things are abundant.
In a sense, I suppose, they're a lot like us.
Be that as it may, I have no response if you insist on asking, "What does the fox say?"
Environmental Almanac is a service of the UI School of Earth, Society and Environment, where Rob Kanter is communications coordinator. Environmental Almanac can be heard on WILL-AM 580 at 4:45 and 6:45 p.m. on Thursdays.