This past winter, my research team and I were busily "cooking" the heads of furbearers, extracting their canine teeth, X-raying those teeth, and making precise measurements of the internal and external dimensions of each tooth.

WHY? In a nutshell, teeth are durable structures that provide reliable evidence of the age and sex of a given animal, even when nothing more than the tooth remains to be analyzed. Furbearer teeth are readily available in North Bay - after all, we are "the wild furbearer capital of North America"! A randomly collected sample of furbearer teeth, therefore, can be used to determine the age/sex ratio of a given population - and this has important implications for furbearer management.

The furbearers of concern are the fisher (Martes pennanti) and the marten (Martes americana), two members of the weasel family. These two species are considered commercially and ecologically important by the fur industry and the Ministry of Natural Resources. Prior to the 1950s, fisher populations were in serious decline; since that time, major management changes were made to allow the populations to recover. Recently, local citizens have been complaining about their pet cats being snatched by hungry fishers, so a review of fisher populations is definitely in order! Marten populations have never been in danger in Ontario but since their preferred habitat (mature coniferous forest) is in decline, many people feel that marten populations should be closely monitored.

For the above reasons, a partnership was formed to combine the efforts of Nipissing University, the Ministry of Natural Resources, and the Fur Harvesters’ Auction. Don Blahut and Mark Downey of the Fur Harvesters’ Auction organized the trappers, who then collected 145 fisher heads and 245 marten heads while operating their traplines. Frozen heads were delivered to Greg Gillespie of the Ministry of Natural Resources, who managed the field data and delivered shipments of skulls to the university.

Once the skulls were on campus, my research team sprang into action. Tanya Ingwersen, Kevan Cowcill, and Jennifer Todd adapted the dentition techniques described in the literature to procedures that could be reliably operated in our lab. Naomi Barratt and Michel Lalande (two students supported by the NIPWORKS Program) boiled the heads in a big pot, extracted the canine teeth with pliers, mounted the teeth on cardboard sheets, and kept track of data. Paul Smylie took the sheets of teeth to be X-rayed at the Smylie Animal Clinic. The entire team then measured and analyzed the X-rayed teeth. As well, my 3^rd year Animal Ecology class elected to experience a "hands on" day of head boiling and tooth analysis to gain insight into the ongoing research.

How do teeth relate to wildlife management? First let me point out that it is the young naïve animals that tend to be most susceptible to predation, trapping, and other forms of mortality. When a furbearer population is trapped, initially the young animals are disproportionately taken; then adult males are captured increasingly; finally, when the other age/sex categories have been depleted, adult females make up a greater portion of the "harvest". The goal of furbearer management is to try to remove that portion of the population that would likely die anyway ("the harvestable surplus") and to leave in place the reproductive adults - particularly the adult females.

Our studies of furbearer teeth showed, for both fishers and martens, that the early collections of teeth were predominately from young animals. In each successive collection throughout the season, there was a higher proportion of adult teeth; yet at no point were adults harvested at a level that would warrant management intervention.

It appears that the 1998-99 harvest was within reasonable limits for both the fisher and the marten populations. We will continue to monitor these animals, with the cooperation of our partners, until a clear picture of population numbers and dynamics can be established.

This study was supported by funding, equipment, and cooperation from Nipissing University, the Ministry of Natural Resources, and The Fur Harvesters’ Auction of North Bay. We are grateful for the X-ray technology and services provided by the Smylie Animal Clinic of North Bay. Tanya Ingwersen received a research award from the Fur Harvesters’ Auction for her contributions to the study.

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