Photo courtesy of daveynin.
The coyote/deer predation issue is, simply, based on available coyote groceries. Coyotes are amazingly adaptable and will eat what’s available. They normally prey on small animals, and when food is abundant they tend to ignore adult deer because they take much more energy to hunt, although they will take any fawns they find. Consequently, coyotes usually don’t have much impact on deer in temperate parts of the country.
A Pennsylvania coyote, for example, can fill its belly with rabbits, rodents, small birds, wild fruit and all the other abundant goodies produced by the state’s fertile soil and easy winters. But that picture changes dramatically in more northern terrain, where the land tends to be less productive and the winters more severe.
Waiting For Winter
It’s hard work for coyotes to kill deer if the snow isn’t deep, and it normally requires a group effort. Canadian biologist Gerry Parker, in his book “Eastern Coyote: The Story of its Success,” wrote, “There are few published accounts of single coyotes successfully killing deer in winter.” Most successful hunts involve two or more coyotes. Even then, wrote Parker, one study revealed that, “Coyotes were successful on … six of 30 chases of deer.” That’s only a 20 percent success rate.
Gerry Lavigne, a retired whitetail biologist formerly with Maine’s Department of Inland Fisheries and Wildlife, and currently on the Deer Task Force for the Sportsmen’s Alliance of Maine, is an acknowledged expert on whitetails and coyote predation.
“Deer move into winter cover (yards) when the snow gets 12-15 inches deep,” Lavigne said. “At that depth, deer have to lift their legs out of the snow to travel, and that uses more energy. At 18 inches, they’re restricted to the best cover in the yards, and with more than 24 inches, they’re restricted to just the trails in that cover. We refer to these three stages as ‘yarding conditions,’ ‘restricted conditions’ and ‘confinement.’
“Winter vulnerability really does it. Deer have to be able to run away, to escape that first 100 yards of a coyote chase. If they can make that first 100 yards, coyotes probably aren’t going to waste their energy continuing the chase. If the snow is just too deep and deer can’t travel through it, they’re going to be vulnerable to that first chase, and they’re going to bog down.
“On average, a major deer yard serves an area six to 10 times its size. So if you improve survival in a 1,000-acre deer yard, you’re actually having an impact on all the deer in the surrounding 6,000-10,000 acres.”
Some winter yards are huge, and harbor big numbers of whitetails. The Armstrong Brook yard, near Maine’s northern border, is 36 square miles in size and holds more than 2,000 deer. But widespread clear-cutting has severely reduced the size of many wintering yards in Maine, and spruce budworm has thinned much of the remaining canopy. Large numbers of deer are often crowded into much smaller yards where, in recent years, the snow depth in the yards increased.
“It became way too easy for coyotes to kill a lot of deer,” Lavigne said. “And they did.”
All the Maine deer yards were severely impacted, and some of the smaller yards, whittled away by logging until they were 200 acres or less, were snuffed out completely after several years of coyote predation.