Fort McCoy habitat suits bull snakes 

By Rob Schuette, Triad Staff

Bull snakes found at Fort McCoy add to a rich and diverse plant and animal population on the installation as well as being an economical and low-maintenance method of controlling unwanted mice in areas such as training ranges.

Tim Wilder, Fort McCoy Endangered Species biologist, said the state of Wisconsin lists the snake as a protected species, meaning it is illegal to kill them. In Wisconsin, the snake is found in a range of land that runs along the southwest and western borders of the state.

Fort McCoy is having transmitters surgically implanted in three snakes and will use information gathered from the equipment to learn more about the snakes’ habitat and range, Wilder said.

"The main purpose is to find their den sites," Wilder said. "The snakes tend to use the same sites year after year."

Having the data about the den sites will allow the Fort McCoy Biological and Cultural Resources Team (BCRT) to better manage the snakes’ habitat.

For example, Wilder said if they can determine den locations for the bull snakes, the BCRT can provide that input to installation officials when they are making decisions about locating projects and help protect the snakes.

Some of the snakes may be difficult to follow in person because their habitat extends into the installation’s North Impact Area, he said.

Josh Kapfer, a University of Wisconsin-Milwaukee doctorate student whose studies focus on bull snakes, is interested in tracking the activities of the snakes throughout the state.

"Fort McCoy has a large number of bull snakes so I contacted Tim last year," Kapfer said. "I want to learn about the snakes in the different habitats."

Snake habitat, like that of many other types of wildlife, also faces threats from construction. Kapfer said when den sites are destroyed from building construction, the snakes often try to enter the building because they are conditioned to find the same location to den each year.

Kapfer said sometime in the future he hopes to compile the information and publish the results in a scientific journal to provide bull snake ecology input to aid in the snake’s management.

The snakes also can provide valuable services to help control the installation’s mice and small rodent population, Wilder said. Around several of the ranges, mice have been attracted to targets because the encasements offer protected sites to build nests inside. The mice also gnaw or chew target wire, which can cause target outages and require repair work.

"Bull snakes like to eat mice so they’re good to have around," he said. "They also don’t require any maintenance and also don’t pose environmental risks as other methods of controlling mice might."

Wilder said the snakes’ habitat at Fort McCoy appears to include grassy or brushy areas, such as barren or savannah. Bull snakes also seem to do well in sandy soils, he said.

Bull snakes are not poisonous and are likely to avoid contact with humans, whenever possible, Wilder said. As with many snakes, bull snakes tend to be more aggressive when molting because their eye sight is obstructed. Since they cannot see well, everything is a threat to them, and they may attempt to bite.

Snakes are cold-blooded, which means their temperature is the same as the surrounding environment, and they can’t generate their own heat, he said. During the winter, the snakes need to find a location below the frost line in order to survive.

In the spring or at other times when the weather isn’t quite as warm, the reptiles can be found on such things as asphalt roads soaking up the heat radiating off of the road. Being run over by vehicles is thought to be a major mortality factor for bull snakes on Fort McCoy, Wilder said.

"Motorists are encouraged to drive around snakes observed on roads, whenever possible."