Common Raven Predation on the Sand Crab

Abstract

We observed three Common Ravens (Corvus corax) hunting for live sand crabs (Emerita analoga) during low tide on Netarts Spit, Oregon in mid-August 2010. One raven successfully extracted four crabs in five attempts during a 5-min period. The ravens hunted on a large sandy beach near the upper margin of the swash zone (the area covered by active wave action); the focal bird extracted buried crabs using an initial thrust of its bill into the sand to flip sand aside, and then followed with two or three additional jabs before removing a crab from the sand. Extracted crabs were pinned on their backs beneath a foot, whereupon the raven pecked at the ventral surface of the crab's body but did not consume the crab. The captured crabs were mature females, and the egg masses they carried appeared to be the target of the raven's attentions. Low tides in late summer appear to be particularly favorable conditions for profitable and successful hunting of sand crab by ravens. This is the first description of the method by which ravens hunt live crabs of any species, and is further evidence of the ability of ravens to exploit seemingly novel and hidden food resources.