Researchers analyzed deer contact at different feeding hubs to find which presented the largest risks
Deer feeders increase the risk of chronic wasting disease transmission by encouraging more contact between wildlife in a concentrated space.
New research reveals that these features that hunters and wildlife enthusiasts often use to attract deer and sometimes supplement their diets may actually be counterproductive to some of their goals.
“It seems like taking these off the landscape should reduce risk,” said TWS member Miranda Huang, a PhD student in conservation sciences at the University of Minnesota.
Chronic wasting disease (CWD), a deadly prion disease, is spreading through populations of white-tailed deer (Odocoileus virginianus) and other ungulates in North America.
The Mississippi Department of Wildlife, Fisheries and Parks was interested in learning more about potential sources for its spread.
The state agency had banned deer feeders, but some hunters and wildlife enthusiasts wondered if they caused any more disease risk than other places deer gather, such as masting oak trees, which drop acorns deer like to eat, or food plots that people plant to attract deer. The agency wanted to conduct some empirical tests to see how risky each of these might be for CWD transmission.
Testing features for disease risk
In a study published recently in the Journal of Wildlife Management, Huang, a research associate at Mississippi State University at the time of this research, and her colleagues put up trail cameras on these three types of features on the landscapes: deer food plots, deer feeders and masting oak trees. They ran the study in northern Mississippi from September 2022 to March 2023—during the winter when wildlife visit these types of resources more often.
They also put fences around some of the deer feeders as a control to exclude the deer, but not raccoons (Procyon lotor), which often use deer feeders as well. They swabbed both types of feeders to test for CWD prions about every six weeks during the course of the study.
Photo analysis revealed that deer visited the feeders at greater rates than masting oak trees or planted deer food plots. They also exhibited riskier behavior for disease transmission at deer feeders—touching each other more often and touching the feeder itself with their mouths. “By all of those metrics, deer feeders were the highest risk between mast trees and feed plots,” Huang said. “You’re concentrating a risk in this five-foot area.”
The swabs revealed that all feeders were contaminated at least once during the study period. Sometimes, the swabs that were previously positive for prions later tested negative, meaning the prions may have passed onto another animal or have fallen off due to rain or wind.
Do raccoons help the spread of CWD?
The cameras around the feeders with deer exclusion fences revealed that raccoons may be helping disease spread. “That was one of our most interesting results—the raccoon feeders did become contaminated,” Huang said.
Ongoing follow-up work has revealed that raccoon paws can carry prions. Raccoons often eat from the same feeders as deer, where they may come into contact with soil containing traces of deer feces and urine—all of which may contain CWD prions shed from infected deer. Research has shown that feeders often contain a higher proportion of deer feces and urine than other areas.
While CWD doesn’t infect raccoons, they may be helping to spread it between feeders, which in turn means more deer could become infected, Huang said. And it may not just be raccoons—other mammals and even birds often visit deer feeders as well, where they might pick up CWD prions and spread them around.
Huang said that her results provide strong support for a continued ban on using feeders in Mississippi.
Other states may also take note. Deer feeders aren’t just a problem for CWD—research has shown that they can help to spread diseases like brucellosis and tuberculosis, Huang said.
The study also shows that deer feeders may work contrary to the goals of the people who use them. Wildlife enthusiasts looking to see more deer in a given area might ultimately end up killing them, for example. Or hunters who use protein pellets in feeders to increase the size of bucks in their area may see weaker animals due to CWD symptoms.
This article features research that was published in a TWS peer-reviewed journal. Individual online access to all TWS journal articles is a benefit of membership. Join TWS now to read the latest in wildlife research.
