TIMING OF REPRODUCTION IN WILD MINK - THE INFLUENCE OF SPAWNING PACIFIC SALMON

In many species of seasonally breeding mammals, reproduction occurs la ter at higher latitudes. Records of timing of reproduction in free-ran ging American mink (Mustela vison) in North America and Europe suggest a similar trend. Observations on mink in southeast Alaska, however, r evealed a deviation from this pattern, suggesting that factors other t han latitude and associated day length may affect timing of breeding f or this species in this area. I investigated timing of reproduction an d body condition of wild, free-ranging mink on Chichagof Island, south east Alaska, and hypothesized that seasonal food availability, especia lly abundant carcasses of spawning Pacific salmon (Onchorhynchus sp.), would determine timing of breeding in this population of mink. Blood progesterone levels, body condition, and testicle lengths were recorde d for 24 adult mink, livetrapped from mid-March to late July in 1992 a nd 1993. Results suggest that these free-ranging mink mate during the later part of April to early May, and parturition occurs in late June to early July. Although male mink seemed to respond to photoperiodism in initiating reproduction, timing of reproduction in female mink was shifted so that lactation coincided with the availability of carcasses of Pacific salmon.