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Undercover omnivores

10/14/2009

There is very little about deer behavior that isn't already common knowledge. Whether they like it or not, deer are probably the most watched, photographed and filmed animals on earth.

Every once in a while, however, someone catches deer doing something completely out of character. If the people who catch the bizarre behavior happen to be a deer biologist and a physician with a long history of deer management, a scientific study is sure to follow.

Two such researchers recently stumbled across some crazy deer behavior, and what they uncovered has to be seen to be believed.

According to their research, deer aren't the strict vegetarians we thought they were. Sometimes deer prefer corn, apples, acorns or clover, and sometimes they just want a nice steak.

That's right. Deer eat meat.

But before anyone starts picking up road kill to use as a big buck attractant, the study also reveals the grave dangers carnivorous deer pose to the future of our deer herd.

"We need to consider rethinking the notion that deer are herbivores and instead consider them omnivores that just aren't good at catching game," said Bradley Thurston, MD, a retired Indiana plastic surgeon and independent deer researcher.

He and Pete Squibb, a Michigan wildlife biologist, conducted a three-year study of the theory in 19 states.

PHOTO GALLERY

Launch Gallery

Using 26 to 58 volunteers every year, the study produced countless trail camera photos of deer reacting to meat offerings. Volunteers placed cameras over deer gut piles and carcasses, dead rabbits and beavers, and on one occasion, even a leftover thanksgiving turkey.

Regardless of where or when the carrion was placed, the study revealed deer visited 63 percent of the sites. In some cases cameras showed deer just looking at the pile, but in some photos it caught them eating the meat.

A review of wildlife literature reveals scattered references of whitetail deer feeding on meat protein.

According to Thurston's and Squibb's study, Michigan DNR records note observations of deer on South Fox Island in Lake Michigan feeding on dead alewives washing up on the beach in the 1960s.

While researching the possibility of wild cougars on the Monongahela National Forest and the Land Between The Lakes in Kentucky, researchers from the Eastern Cougar Foundation noted whitetail deer were by far the most numerous species to visit camera traps baited with meat and scent.

More recent studies have also exposed deer as nest predators of some ground nesting birds.

The Thurston/Squibb study revealed deer as more omnivorous than ever previously recorded, however. Instead of making conclusions based on isolated observations of deer eating bird eggs and fish, this study offers scientific evidence that deer eat everything from rabbits, to turkeys, to other deer.

Dire consequences

None of this was meant to simply be content for lively conversation over cocktails. Deer feeding on the carcasses of other deer is potentially very serious, and is a new front on the war against disease in deer and other wildlife.

"We know that both tuberculosis and chronic wasting disease produce organisms or transmittable material which is accumulated in the internal organs, connecting tissue and mesentery fat," Thurston said.

But even after the edible carrion is gone, the threat lives on.

According to the study, it has also been shown that organisms and agents such as CWD and Bovine Tuberculosis are transmitted to the soil. As a carcass decomposes, transmission appears to be viable for a period of years.

TB organisms have been shown to readily infect other deer feeding in an effected area six months after initial infections.

The transmittable material from CWD is not as hearty as that from TB, but it also remains a threat.

Recent findings indicate the prions causing CWD can persist in the environment for long periods of time and retain their infectious capabilities, the study revealed.

Though the study wasn't intended to change the way deer hunters conduct themselves while hunting, it should have that effect.

In the growing number of states where CWD has been detected, as well as places where TB has been a concern for decades, hunters should take note.

If we know deer will at least visit and inspect dead deer, and that some will even eat the remains, is it safe to ever leave a gut pile in the woods again?

Even in places where it is assumed predators consume remains before they become a risk for other deer to eat, there are issues.

One set of photos used in the study showed a deer visiting a gut pile only minutes after the same camera took a clear shot of a wolf in the exact same spot. And unless the predator removes all the soil from around the infected animal, infectious material is still present.

While this study certainly yielded enough scientific evidence to make everyone take notice, both Thurston and Squibb think more information needs to be collected.

"We think further investigation is necessary to document the extent of risks these sites have as a potential transmission vector to deer and other wildlife species," Thurston said.