Tuesday, 24 April 2012
Carrion Crow vs Shore Crab: fight, fight, fight!
Photographed at Barns Ness in East Lothian last Sunday morning, this crow carefully manipulated this female crab onto its back and then twisted its tail off. After swallowing the tail the crow continued foraging, leaving the hapless crab to scuttle off, possibly mortally wounded.
I was left wondering whether the crab would survive, whether the crow had been hoping for an egg-mass under the crab's tail, whether the handling costs of dealing with the rest of this meal were just too high for the crow, or whether this behaviour would benefit the crow by eliminating a competitor from its patch.
Reaching for Birds of the Western Palearctic I find that crabs are not even listed as a food source for the Carrion Crow - the only Crustacea mentioned are woodlice and crayfish. Presumably there were no published studies of the diet of shoreline crows, as I am sure crabs would feature regularly. Certainly having been fortunate enough to have been working on BWP at the time Volume VIII was written and I can certainly vouch for the thoroughness of the research.