Coyotes Kill Deer, Not Deer Herds

But here’s something most deer hunters hate to hear: No matter how many coyotes you shoot, they’ll still be hell on fawns.

Coyotes can affect a deer herd’s size, but they can’t cause its decline on their own. Granted, when deer numbers are low, coyotes can keep them there. In fact, they can drive them even lower unless wildlife managers reduce hunting quotas for antlerless deer. However, the bigger factors affecting deer numbers are habitat quality and extreme weather, such as prolonged drought in arid climates and deep snow with subzero winters in the North.

Skilled Hunters
No one should question the coyote’s hunting skills. They can also kill adult deer. In fact, Ontario researchers John Benson of Trent University and Brent Peterson of the Ministry of Natural Resources documented four different coyote packs killing moose in central Ontario during the 2008 and 2009 winters.

Evidence at the kill scenes verified these were hunts, take-downs and fresh-meat feasts; not mere carcass scavenging. In fact, the researchers documented five other likely coyote-on-moose kills, but evidence couldn’t verify the predator. Benson and Peterson cleared wolves as the culprits, given kill-scene evidence and an alibi: Wolves are rare in the study area.

The evidence they checked for each kill included GPS data from collared coyotes in the packs. If the coyotes remained clustered in one site three or more hours, the researchers investigated. Other evidence was freshly broken vegetation; fresh blood sprays on snow, rocks and vegetation; moose hair embedded in tree bark; and shredded stomachs and ripped-off legs, indicating the moose wasn’t frozen when coyotes tore into it.

Of the four verified coyote kills, two moose were 20 months old, one was 20.5 years old, and the other about 6 years old. Marrow in their leg bones, which can reveal weakness or starvation, showed no evidence of severe malnutrition.

The researchers cited five factors that helped the coyotes prevail.

• Deep, crusted snow that can support running coyotes
• Steep hillsides of 40 to 45 degrees, which physically tax moose more than coyotes
• Dense pine/spruce stands, which make it hard for moose to whirl and kick
• The 20.5-year-old moose likely had osteoarthritis, which often plagues older moose
• Few whitetail deer in the area, forcing coyotes to try hunting moose

If coyotes can take out adult moose in certain situations, who would say they can’t handle adult deer, which are often one-fourth to one-fifth that size? In fact, researchers have documented adult deer remains accounting for about 40 percent of the coyote’s diet in some areas during winter. Research also documents coyotes killing and consuming twice as many adult deer during winter than they were taking fawns during summer.

As Professor Mike Chamberlain from the University of Georgia told a National Deer Alliance gathering in 2015: “Twenty years ago, I thought all the deer remains we found in a coyote’s winter diet came from scavenging. That was misguided. I no longer believe that. Yes, they’re opportunistic and they’ll take what they find, but they can’t survive on scavenging alone. They’re predators.”

Surviving and Thriving
Even so, deer and other prey species evolved alongside predators like bears, wolves and coyotes. And given large areas of good habitat, they thrive despite them. Surviving starts with “predator swamping,” which refers to the fact that deer, moose, pronghorns and other prey drop their young about the same time, thus “swamping” the landscape with more fast-growing prey than predators can target while fawns and calves are most vulnerable.

Some unique situations, however, can leave pronghorns—and mule deer, to a lesser extent—vulnerable. Jim Heffelfinger, a wildlife science coordinator for the Arizona Game and Fish Department and research scientist at the University of Arizona, said small, isolated pronghorn herds in a valley between mountain ranges could “blink out” from sustained predation. To prevent it, the wildlife agency sometimes conducts aerial coyote shoots, which are most effective in wet years. In dry years, most pronghorn fawns die anyway.

Still, even if we believe coyotes can drive deer herds to unhuntable levels, can we do anything to permanently remove or neutralize this native predator, which many hunters deem a four-legged poacher? In turn, will coyote suppression generate more deer?

Probably not. Heffelfinger and the rest of the scientific community think both feats would require intense, permanent, landscape-level trapping. In Heffelfinger’s book, “Deer of the Southwest,” he writes: “Killing predators in a vague attempt to blindly ‘help the deer’ is not likely to accomplish anything meaningful in terms of deer abundance.”

Craig Harper, a wildlife professor at the University of Tennessee, put it this way: “It requires constant attention. It’s just like weeding. It must be a way of life if you want things right.”

John Kilgo is a research wildlife biologist at the U.S. Forest Service’s Southern Research Station in Asheville, North Carolina. He has studied the coyote’s impact on whitetail deer since 2005, and has published 16 scientific articles on his findings. Kilgo said extensive, intensive trapping can reduce coyote numbers, but he’s skeptical it can be sustained for long.

Sustained Frustration
For instance, when Kilgo trapped coyotes intensively for three years in one study, it apparently helped produce more fawns the first year, but then didn’t help at all the next two years. And that was done by seasoned trappers.

“The average deer hunter isn’t a trapper,” Kilgo said. “Their likely opportunities to remove coyotes is during deer season while sitting on their stand. That’s a drop in the bucket. It won’t have any effect on coyotes or your deer hunting.”

Kilgo doubts bounties will ever make a difference, either. “Even if you had ready access everywhere, I doubt anyone, anywhere, will ever kill enough coyotes to make a difference on deer herds. The result of extensive bounties out West didn’t achieve what they hoped. We now have coyotes across the entire continent. I doubt bounties would ever make a lasting difference.”

Kilgo said coyotes are quick to adapt and even quicker to fill gaps in their range. As fast as you remove them from one site, they send in “replacements” from another site. Further, research from Canada and Western states previously found that “persecuted” coyote populations generate larger litters in response, especially when older adults are around to do most of the breeding.

Kilgo, Heffelfinger and other researchers agree coyotes can affect deer and deer hunting, but think it’s time people accept that neither animal is going away. They think coyotes are here to stay, no matter how much we shoot, trap or study them.

“When I was in college in the 1970s, my major professor was studying the coyote’s impacts on whitetails in South Texas,” Heffelfinger said. “And people today everywhere are still doing coyote-whitetail studies. The results, the answers, aren’t changing.”

Feature image by Matt Hansen.