Scavenging by fishers in relation to season and other scavengers

Abstract

Carrion is an energy‐rich resource that benefits many organisms, but scavenging involves both profits and risks. Fishers (Pekania pennanti) are forest‐specialists that scavenge large carcasses but quantitative assessments of their scavenging are lacking. We quantified three characteristics of scavenging behavior by fishers: (a) whether fishers visited a carcass; (b) the time to first visitation of a carcass by fishers; and (c) how long fishers fed at a carcass. We then evaluated the importance of habitat characteristics, cues from other scavenger species, and season on the scavenging behaviors of fishers. Fishers scavenged 25 of the 89 deer carcasses we monitored, and visited carcasses more frequently in winter (n = 22, 34%) than in summer (n = 3, 12%). Time to the first fisher visit to a carcass averaged 4.7 (±1.1 SE) days. On average fishers made 26 (±9 SE) repeat visits to each carcass they found and fed for 118.1 min (±42.3 SE) over an average of 6 days; season also influenced their feeding times (120.3 ± 46.0 SE min in winter versus 63.7 ± 44.7 SE min in summer). Fishers had a crepuscular activity pattern while scavenging, but initial visits peaked mid‐day in addition to a peak near sunset. Our results suggested that fishers may use cues from other scavengers to detect carrion, but that habitat characteristics did not affect exploitation of carrion more than other variables. These results highlight the potential importance of carrion for the foraging ecology of fishers, particularly during times of resource scarcity. Further research based on identifiable individuals is needed to quantify fitness consequences of scavenging for fishers, including possible negative effects of intraguild predation at carrion.