Predator-Prey study: Wolves not threat to deer you may think

Deer

Researchers are learning that predators, winter weather and habitat influence deer populations and survival. Photo: Dave Kenyon, Michigan DNR.

By Howard Meyerson

In the snowy woods of the western Upper Peninsula, wildlife researchers are learning a thing or two about deer survival: what preys on adult whitetails and fawns — and what else contributes to their deaths.

Some in the hunting community presume the answer is wolves. Many know harsh winters take a toll. Both are true, according to recent research, but a lot depends on other factors, such as the availability of young forests and food, predator density, and what other prey are available.The study, started in 2009 by Mississippi State University and the Michigan Department of Natural Resources, has turned up some surprises.

“We’ve been surprised by a few things in Phase I (low‑snow study),” notes Dean Beyer, a researcher with the DNR. “We learned that adult does were avoiding core wolf areas and that coyotes were avoiding them, too. That put coyotes and does in the same area, which probably resulted in a greater mortality by coyotes. And we were all surprised by the rate at which bobcats killed fawns. The rate is much higher than other species.”

DSK220 17 DNR

Predation the leading cause of deer mortality. Photo: Dave Kenyon, MDNR.

Coyotes and deer

The study, known as The Predator Prey Projectis a three‑phase endeavor that examines ecological interactions in low‑snow, moderate‑snow and deep‑snow regions of the western U.P. The answers are being derived by tracking deer fitted with radio‑ telemetry collars and predators fitted with GPS collars. The low‑snow work wrapped up in 2011. The moderate snow work is slated to finish this year. Then three years of deep‑snow work will begin, provided funding can be found. Two Phase I findings are particularly interesting.

“Predation was the leading cause of mortality, 3.5 times more hazardous than human‑caused mortality sources,” the preliminary report states, along with “Overall, coyotes were the leading cause of adult female mortality, followed by wolves.” Predation by black bears was infrequent and considered “opportunistic,” and wolves were not considered important predators for fawns.

Beyer suggests the proximity of coyotes and deer boosted those mortality numbers. Wolves in the low‑snow zone were often feeding at livestock carcass dumps.

“Coyotes in Phase I were the biggest and most important predator of fawns and adult does,” Beyer said. “In Phase II (the moderate snow zone) coyotes cause the most total mortality of fawns, but when we look at adult deer, wolves jump up to No. 1; I think because they don’t have the livestock carcass dumps.”

The winter season also has an impact, according to the report: “Adult female mortality was greatest during winter (44 percent of those deaths), followed by spring/summer (37 percent), and fall (19 percent).”

Weak fawns 

Winter severity, which can hinder a deer’s ability to move around and feed, in turn can affect fawn size at birth. A 2.‑pound reduction in a newborn fawn’s weight can increase mortality by 11 percent, the research shows.

“Phase II has been interesting because we have had some very severe winter conditions,” Beyer said. “A couple of things jumped out. In 2013, (adult) doe survival was 58 percent, which is on the low end of things. In 2014, when we had even more severe weather, doe survival was 38 percent — some of the lowest survival rates I’ve seen in the literature. Those conditions stressed the does, and the fawns were born in poor condition.

“We pretty much lost the fawn crop in 2013 and had fairly low fawn survival in 2014, when 11 percent of the fawns survived.”

For those who remain certain that Michigan wolves will decimate the deer herd, Beyer suggests it is unlikely. The two species, he says, have evolved together, and other factors influence outcomes. Habitat and predator densities are just two. Then there are predator’s energy needs. Coyotes, for instance, are more likely to kill fawns while wolves are more likely to kill adult does. They need more meat/fuel to sustain themselves.

“What we know from the scientific literature is there are only two reports where wolves are believed to have contributed to a substantial reduction of deer … winter weather is still the driving factor, even in the low‑snow zone,” Beyer said.

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Appears in MLive Media Group newspapers and  MLive Outdoors.

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7 Responses to Predator-Prey study: Wolves not threat to deer you may think

  1. Wayne Andersen says:

    Howard, as usual a very informative and interesting article. I am sad to know this is the last article of yours as a newspaper columnist . Thanks for the great work you have done for so long informing and educating the readers of Grand Rapids Press. I look forward to your continuing articles in other publications.

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    • Wayne. Appreciate your comments. As you know, its’s been a good and long run, working with the Grand Rapids Press and MLive. I too look forward to the upcoming articles in other publications. Stay well. –HM

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  2. Thank you for your awesome article, Howard. It does certainly give one pause to think. Wolves here in northern Wisconsin are blamed by many as the sole source of the declining deer population, but you make many good points here that there are many causes of deer mortality. Very informative and interesting!

    Liked by 1 person

    • Beckie. Thanks for comments. The research underway is pretty interesting. There is a lot more being discovered and recommended than I had space for in this column. Consider sharing the link to the full study (above) with others. I suspect the same dynamics play out all across the wolf range in the Great Lakes region. –HM

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  3. Joe Allen says:

    My name is Joe Allen, I am a forester, hunter and trapper. My weeks consists of 6 days of being in the woods. My education did not come from a Phd or a college degree. I have caught and released over 100 wolves in the last 6 years. This year I caught 11 wolves before I caught 1 single coyote. I have done research on my own last May on 8 scat samples of a residential pack of wolves. My finds were 14 fawn hooves on 8 samples. I completely disagree with Dean Beyer. I have advised wolf research experts where the large packs reside in Gogebic county, so my knowledge of these apex predators is well founded. I have watched deer populations drop to a lower level then in 1968. I am also in fear of losing our fragil moose population, which has dropped over 130 animals in the last year and a half. I have hunted most of the northern Canadian provinces and Alaska and it is kind of funny that all the Canadian and Alaskan game biologists seem to say the biggest impact on big game populations is due to high wolf numbers. My summary of this is that I will debate Dean Beyer on the true impact of wolves in the UP of Michigan on national TV. My final belief is that we have a biologist from Yellowstone that is biased. Peace out!!

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    • Thanks for your comments Joe.

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    • Rork says:

      You could have tried to debate something specific Dean Beyer said, but you failed to do that. I cannot dispute much of anything you said, cause you didn’t say much except about how great your knowledge is, and that you have anecdotes to tell us. Yes, deer are down – and most biologists still think weather, and winter habitat, is the most influential factor. The last two winters running, a fawn not killed by a predator was very likely to be killed by winter, and by becoming dead early, left more food for others – ever heard of compensatory death? What was said in the article is almost entirely from the low-snow part of the study (where less coyotes might be a good thing. and one way to knock down coyotes is to have wolfs) and will change for deeper snow areas. Oh, and this isn”t Alaska.

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