THE COMPOSITION AND INTERACTIONS OF SCAVENGERS ON A HUMPBACK WHALE CARCASS IN ALASKA

Abstract

Many avian and mammalian predators are facultative scavengers and will opportunistically forage from carcasses. A food source as large as a whale carcass could be valuable to wildlife because of its size and high lipid content. Large carcasses can elicit unique behaviors and interactions in wildlife, but because whale beachings are relatively uncommon, little research has examined the scavenging dynamics at whale carcasses. Here, we used a remote camera to investigate the composition and interactions of scavengers at a Humpback Whale (Megaptera novaeangliae) carcass that washed ashore in Glacier Bay National Park, Alaska, in 2016. We split the consumption process into 3 stages based on how much soft tissue remained. Bald Eagles (Haliaeetus leucocephalus) were the first to feed on the carcass and appeared to dominate the food source, preventing many smaller birds from feeding. Gray Wolves (Canis lupus), corvids (Corvus spp.), and gulls (Larus spp.) were also regularly detected. Scavenger numbers remained high during the first 2 stages of carcass consumption and declined by the 3rd stage. Most interactions observed were between individual Bald Eagles and occurred during the 1st stage. Following the eagles' departure after the 1st stage, interactions between individuals were far less common. These results suggest that a carcass of this size in the intertidal zone is utilized primarily by avian scavengers and that interactions between individuals decrease as the food resource declines. These findings help advance our understanding of scavenger dynamics and the general ecology of coastal Pacific Northwest ecosystems.