There is an article in our 'The Wisconsin Trapper' magazine by the DNR furbearer research scientist, Nathan Roberts. In the article he updates what's going on with bobcat, fisher, and otter in our state. We are required to turn in the skinned bobcat carcass when the pelt is tagged primarily to age the animal. "The lower canine tooth is taken and sent to a laboratory for analysis. The tooth root is cut into discs. These discs are examined under a microscope for rings that indicate how many winters the animal has been alive-similar to how trees are aged." They also examine the reproductive tracts and estimate what the pregnancy rates are for each age group, and the associated litter size. It appears this methodology give them the age structure of the critters in the state. And I'm going to assume that they are also getting a fair look at the population numbers too. They are also doing the same aging technique on the fisher, but we only have to turn in the lower jaw for that. The river otter info is taken every three years, so the skull or carcass is not required to be turned in this season.
"The only constant----is change."