Age Structure Differences in American Mink , Mustela vison , Populations under Varying Harvest Regimes
Two American Mink populations were examined using canine tooth cementum annuli to assess age structure of harvested segments of the populations. Trapping mortality was different between these two populations. Comparisons are made with a Montana Mink population. I propose that forbearer managers can readily assess relative harvest pressures by analyzing the age structure of a Mink population, and offer management recommendations for populations displaying various age structures.
Organochlorine contaminants in wild mink from the lower Great Lakes basin, Canada, 1998–2006
Organochlorine contaminants were measured in livers of wild mink (Neovison vison) trapped in the lower Great Lakes basin from 1998 to 2006. To assess exposure and potential risk in mink feeding on Great Lakes biota, concentrations of contaminants were compared in mink trapped within 7.8 km of the shoreline as well as at inland sites (i.e., 8–40 km). Overall, significant spatial variation in mean hepatic concentrations of sum PCBs and seven other organochlorines was found in mink from 13 Great Lakes sites, many of which are within the Great Lakes Areas of Concern. Mean sum PCB concentrations, on a lipid weight basis, ranged from 2 μg/g in mink from inland Lake Ontario sites to 44 μg/g in mink from western Lake Erie. Concentrations of other organochlorines in mink were generally low. Mink from western Lake Erie had the highest mean cumulative organochlorine burdens dominated largely by PCBs. A significant age effect was found with 1-year-old mink having significantly higher PCB burdens than mink less than 1 year in age. With respect to published PCB threshold effect concentrations, some mink exceeded those associated with effects on reproduction and survival as well as the presence of jaw lesions. This was most consistently found in western Lake Erie where the health of populations of wild mink may be adversely affected and where no mink 2 years of age or older were collected.
Marten Home Ranges and Population Fluctuations
Live trapping was initiated in 1952 on a six square-mile area in Glacier National Park, Montana, to obtain quantitative ecological data on a population of marten ( Martes americana ). Field work for this report was conducted during the periods shown in Table 1. Investigation of marten ecology on the study area is continuing.

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Table 1 
Field periods and trapping effort



Methods used and description of the study area were presented previously (Newby and Hawley, 1954). The 1954 progress report did not give final figures for the size of marten home ranges and gave little information on population dynamics. The present paper will discuss these aspects of the study based on the more extensive data now available.

A total of 3,993 trap units was set during the study period, resulting in 525 captures of 85 marten (54 males and 31 females). Forty-nine marten, or 57.6 per cent, were recaptured at least once. The highest number of captures of one individual was 73 for an adult male over a period of 562 days. Male marten, with 391 captures, accounted for 74.4 per cent of the captures but composed only 62.3 per cent of the marten captured. The average trapping effort required to capture one marten was 7.6 trap units in total, but varied from 2.8 to 11.9 trap units per marten during the various quarterly periods. The winter period required the least trapping effort.

Live trapping of marten produced quantitative information on their home range size and on their relationships with each other and with the habitat. Minimum home ranges were delineated by connecting the outside points of capture as plotted on a map prepared from aerial photographs (Fig. 1). Home range areas were obtained by the use of a planimeter. This method was used because it encloses an area within which the marten …