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Home ranges of nine minks Mustela vison in southern Sweden were studied by telemetric techniques during eleven periods in 1968-69. Data obtained allowed accurate determinations of the boundaries of the ranges and quantitative descriptions of the distribution of use-intensity. Information on seasonal movements were obtained by trapping and marking. The adult male occupied the largest home range, twice as large as that of the juvenile male. Adult females kept within smaller ranges than the adult males. In winter the minks tended to concentrate their activity to restricted parts of the home ranges. The great irregularity found in intensity of use of the home range may be due to the availability of food. An adult female may temporarily hold a territory against an adult male. The balance, however, demands more attention from her at the common border. Unlike juvenile females, juvenile males did not seem to be allowed to stay within the ranges of adult males. The dispersal of juveniles started in the beginning of July and most of them left the study area. The extent of male movements during the mating season was greater than during the rest of the year.

The food habits of the mink in Sweden were studied in three different habitats by means of scat analyses. The entire material contained 4,738 scats. There were very marked seasonal variations due to changes in the relative availability of the prey. The principal food groups were mammals, mainly rodents, birds, fish, and crayfish. Crayfish occurred most frequently in the summer food, due to its higher activity in the warm months which increased its vulnerability. Fish was consumed preferentially in winter and spring. The great availability in these seasons was a result of increased vulnerability due to low water temperature. Frogs were secondary food and occurred most frequently in the diet at seasons when the mink changed its food habits. Birds occurred most frequently in the diet during migration and breeding seasons. Rodents constituted a very variable source of food due to the great fluctuations of their number. Their availability influenced the food habits in a conspicuous manner, particularly in the northern area investigated. The greatest changes in the food habits occurred in late spring and in the autumn. Differences between habitats with regard to food habits were most marked in summer. At other seasons the food habits were dominated by the great fish consumption. Pe3ioMe

Activities of six minks (Mustela vison) in southern Sweden were monitored during nine different periods in 1968-69 by radio-tracking techniques. Diel activity patterns were determined and related to availability of prey, reproduction cycle, and certain environmental factors. 1. All the wild male minks studied were mainly nocturnal at all seasons. The level of activity tended to increase with increasing length of night and with decreasing temperature. In general, the activity peaks of male mink corresponded to peaks in prey activity. 2. The female studied showed a very low activity during pregnancy. During the litter period when she was mainly diurnal her level of activity was considerably higher.