The University of Michigan is catching heat for its decision to use dry ice to control its groundhog population on campus.
U-M Director of Community Relations James Kosteva said that the university started with a trapping method, but could not confirm when. He said it appeared that individuals in the area were either setting off the traps manually before the animals could be captured or that the animals were being released before personnel could remove them from the site.
That’s when the school turned to dry ice to deal with its groundhogs.
The way it works is by dropping dry ice, or odorless carbon dioxide in frozen form, into burrows to try to suffocate the animals, as the dry ice “sublimates from a solid to a gas,” according to a USA TODAY article from last year about how municipalities around the country have employed the method to combat growing rat populations.
Dry ice can be deadly to small animals at high concentrations, according to USA TODAY.
Kosteva said in an e-mail that university personnel have used this method fewer than 10 times over the course of about two months on the university's north campus.
Kosteva said that groundhogs can pose risks, as their burrows can make building foundations susceptible to damage, leading to failure and pose as minor trip hazards to pedestrians. Kosteva said in an e-mail that the university had to recently repair a sinking electrical substation on campus because the foundation was undermined by groundhogs.
“It might be surprising to people but groundhogs do move a lot of dirt,” Kosteva said. “They do have a tendency to do some of their burrowing in the vicinity of foundations, building foundations, porches, sidewalks and the like.”
Wendy Welch, communications director at the Humane Society of Huron Valley, described the method, in which dry ice is placed in the groundhog dens until they die of suffocation, as “cruel.”
“We understand that people get frustrated with wildlife sometimes and come up with other methods of dealing with them, but this is not an accepted or researched practice within wildlife management, for sure,” Welch said.
The Humane Society of Huron Valley received a complaint about the method being used near Fire Station No. 5 on Beal Avenue, which is university-owned property. Welch said in an e-mail that the humane society received a complaint by phone on Aug. 21 that U-M was planning on using dry ice to kill a family of young gophers.
Kosteva said that the university had eyewitness evidence that individuals were feeding the groundhogs, which Welch of the humane society said is not advisable because it can create dependence on humans and make them accustomed to people.
Welch said that there are other, more humane methods that can be used to address the problem, such as repellents, modifying the den, and visual deterrents to scare them away.
“We really just think that this is a backwards way of temporarily — quote unquote — solving an issue, if it really is solving,” Welch said.
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