URBANA, Ill. -- According to a University of Illinois study, groundhogs, also known as woodchucks, may have a better survival rate in urban settings than in rural areas.



The study is being conducted in response to a request from the Illinois State Department of Natural Resources for current data on how woodchucks are responding to changing land-use practices.



"There was a sense that the numbers of woodchucks in Illinois was declining and they were concerned about the population," said U of I wildlife ecologist Robert Schooley. "They didn't know what was causing it. One idea was the increase in the number of coyotes. And there was a general concern about how urbanization might be affecting wildlife, including woodchucks."



Two factors may be working in favor of the survival of urban woodchucks - they are getting more habituated to humans and so keep eating even when humans are around. And, they also have fewer predators like coyotes in urban settings.



Liza Watson, U of I graduate student in wildlife ecology in the College of Agricultural, Consumer and Environmental Sciences, has been tracking both urban and rural woodchucks for nearly two years.



"I'm looking at how they're adjusting in urban settings by examining their survival rates, movements, and their general vigilance behavior," Watson said. She explained that vigilance behavior is when they are alert and scanning the landscape for predators.



Woodchucks primarily rely on their sight to spot a predator rather than scent, so if there is any kind of disturbance, they stop what they're doing and look in that direction.



"If you're standing up on your hind legs all the time looking for predators, you can't be feeding, and in order to survive hibernation, they need to spend as much time as possible feeding during the active season. There's only so much time in a day, so there's a trade-off there. If they're living in an urban setting, they might be less vigilant because they've become habituated to human disturbance and so they can spend more time foraging for food," Watson said.



Watson said that woodchucks lose 35 percent to 40 percent of their body weight during hibernation, which is typically from mid-November to late February or early March.



Watson trapped 41 adult woodchucks. The animals were anesthetized and surgically implanted with tiny radio transmitters. The implants allowed Watson to follow each animal and to know which of the 41 animals she was observing.



"In the summer, they tend to be active in the early evenings, so I'd drive around looking for them and I videotaped them from the vehicle, at least 30 meters away. They typically don't respond to cars, so as long as I stayed in the truck, I could observe them without disturbing them," she said.



The transmitter has a mortality sensor so it beeps slower if the animal hasn't moved in over eight hours. "We can bring them back to the vet school where they conduct a necropsy to determine how they died," Watson said. Currently there are 22 remaining from the original 41 that were tagged.



"In rural areas, we think most deaths were caused by a predator, such as a coyote, because we'd find just the transmitter and some remains," Watson said. Four of the rural animals also died in hibernation. "This usually means that they didn't have enough fat stores when they entered hibernation. They're herbivores, so even if they did wake up early from hunger and come out, there wouldn't be anything green enough to eat." Woodchucks eat grass, clover, dandelion, some garden vegetables and some agricultural crops.



The question is -- does urbanization give the woodchucks a natural buffer zone to protect them from predators?



Schooley says yes.



"We also think that woodchucks may know that urban settings are not as risky an environment. We're trying to see whether they have become habituated to humans. You've seen a tree squirrel that you can get within a foot of before they run. In the same way, if woodchucks become habituated to humans, they'll realize that urban areas are safe and be able to be less vigilant and feed more," Schooley said.



The study also looked at how far woodchucks travel from their burrow. In the city and residential areas, woodchucks have fewer natural predators and food available from gardens and plantings, but the flip side is that their habitat is fairly fragmented. The study found that urban woodchucks have restricted movements and consequently smaller home ranges than rural woodchucks.



Funding for the research was provided by the University of Illinois and grants from the American Society of Mammalogists and the American Museum of Natural History.



SOURCE: University of Illinois.