Thursday, March 13, 2008

RESEARCH NEWS: Artificial Feeding Endangers Deer Health

It’s difficult to argue with data from sound scientific studies.

Three Wisconsin wildlife biologists have evidence from their studies in Wood County that support a hypothesis that fed deer are more likely to transmit diseases because they have more deer-to-deer contacts when feeding close to one another. Deer may even become aggressive with each other during these situations.

If a deer disease is transmitted through the animal’s digestive tract, deer at a feeding station could become infected with some transmissible diseases without direct contact with another animal.

It shouldn’t matter if the deer are fed so they can be observed or hunted. Whether one calls it feeding or baiting, it’s basically the same as far as deer reactions.

Abbey Thompson, Michael Samuel and Timothy Van Deelen, were all at the University of Wisconsin when the study was conducted during the 2003-2004 and 2004-2005 winters.

Data from this study shows that providing shelled corn to deer in troughs, piles or spread over areas, increases deer-to-deer contact rates and also provides many opportunities for indirect contacts, compared to natural browsing.

Supplemental feeding poses risks for both direct and indirect disease transmission due to higher deer concentration and more intensive use of the area, compared to control sites, Van Deelen and his colleagues report in the Journal of Wildlife Management.

In their paper, “Alternative Feeding Strategies and Potential Disease Transmission in Wisconsin White-Tailed Deer,” the researchers make their case that none of the feeding strategies they studied substantially reduced the potential risk for disease transmission. Therefore, they say, banning supplemental feeding is warranted.

Some hunters and politicians have argued that by changing how deer are fed or baited would reduce or eliminate the potential for disease transmission. They suggest that smaller piles, for example, could reduce the chances of transmission.

Not so, Abbey, Samuel and Van Deelen report.

The study was conducted at Sandhill Wildlife Area, near Babcock, Wis., in Wood County. Four upland feeding sites were chosen. Sites, where deer traditionally concentrated during winter, were used as control (no food provided) sites.

Deer populations were 34 and 18 deer per square mile of habitat during 2003-2004 and 2004-2005, respectively.

Six experimental treatments were conducted at each of the four feeding sites, including providing two gallons of shelled corn, replenished daily and unlimited shelled corn, replenished daily.

The feed was offered in three ways — in a pile, spread on the ground and in a trough.

Motion-sensing digital cameras were used to monitor deer using the feeding and control sites.

The researchers studied images, taken at 15 second intervals for 15 minutes, to calculate deer-use minutes, behavioral interactions and distances between deer.

“Deer become more food-stressed and less selective in what they eat from early to late winter and our experiment was designed to balance all these things,” Van Deelen said.

“The upshot is, relative to foraging in a normal winter situation, the different limitations on baiting, such as spreading food, putting it in a pile or in a trough or limiting it to two gallons had very minor impact on reducing deer use minutes over bait sites,” Van Deelen said.

The researchers added another sub-experiment to their study.

“Deer pellets (fecal pellets) from the area were added to the corn to determine if the deer would avoid eating the pellets,” Van Deelen said. “Relative to corn, they were eating about a quarter of the pellets mixed in.”

Van Deelen believes that if corn is on the ground and if the infectious disease is passed through the digestive system of a deer, there is a mechanism for infecting animals over a bait site because deer pellets are consumed by the deer.

Direct contact between deer also provides another mechanism of transmission.

“Abbey demonstrated that fecal-oral transmission can occur in a wild setting,” Van Deelen said. “On the other hand, when deer are eating browse, held aloft and not replaced during the winter, the transmission mechanism is not there.”

The researchers believe banning feeding and baiting statewide makes sense.

“Why would you place a mechanism of disease transmission out among healthy deer, when there is one area generating infected deer?” Van Deelen said. “If you want to protect a deer herd, a ban on baiting and feeding makes sense in the presence of chronic wasting disease and tuberculosis.”



Marc - Editor, NYBOWHUNTER.COM said...

That is a very interesting post. I hunt in CT where they do allow baiting for deer and I spread one 20lb bag of corn in a 30 yard radius around my tree. The thought is by spreading corn on the 20 acre or less property I hunt, I will be able to draw deer from neighboring properties to my stand location. After reading this article though, it makes me start to wonder if baiting deer is really worth the risk it poses to their health?

Tom Rooney said...


I can't answer that question for you, but I am glad that I got you thinking.