PREY-DEPENDENT PROFITABILITY OF FORAGING BEHAVIOR OF MALE AND FEMALE ERMINE, MUSTELA-ERMINEA

Net benefit of foraging behaviour for both male and female ermine was obtained by estimating energy costs of time invested in resting, searching or handling behaviours, and energy gained from capture of each prey species. For male ermine, hunting behaviour and capture frequency varied little between prey types. Foraging profitability was influenced by search time, and was highest with Peromyscus maniculatus and lowest with Blarina brevicauda. In females, profitability was influenced both by hunting behaviour and by capture frequency, and was highest with Microtus pennsylvanicus and lowest with Blarina. Data support the idea of feeding niche separation between sexes, males being more generalists. Females would probably maintain feeding preference for Microtus, even in times of low prey density. -from Authors