"When you find a collar that's completely stretched out, found on a fence, found on the ground under bushes, it's very clear to us that it was snagged on something," Carter said.
When researchers find and collar more fawns this spring, they plan on making the collars a little tougher and tighter. And even though some people may think that could lead to a deer choking to death, Carter said that this technique is used widely in such studies and there have been no reports of a collared deer ever choking to death.
But researchers did find that urban deer were more likely to be killed by vehicles, while rural deer were more likely to be killed by coyotes. Of the fatalities, seven were in Bloomington, with five due to vehicle collisions and two deaths from domestic dogs.
There were four fawns killed in rural areas, with three from coyote predation and one from abandonment.
Williamson said researchers could tell the coyotes killed fawns because there was little left; with dog kills, the fawns were killed and left alone.
One of the bigger surprises involving the deaths was that they occurred at different times in the animals' development, depending on whether they were in rural or urban settings.
Out-of-town fawns had higher mortality early in their lives and then very late in their first year, when hunting season was open.
In town, it was the opposite, with fawns doing well early and late in their first year and having more fatalities in the middle of the year, most often in late August, according to Williamson.
"It's when the car collisions happened a lot," he said. "We're affectionately calling it the 'terrible twos,'" because it is when the fawns were old enough to leave their mother's side and begin exploring.