RUBEGA, M.A.; GJERDRUM, C.; YANEGA, G.; University of Connecticut, Storrs; University of Connecticut, Storrs; University of Connecticut, Storrs: Motor pattern conservation and feeding mechanics in Scolopacid shorebirds

All but a few of the shorebirds in the Scolopacidae are precocial and entirely self-feeding from hatch, which implies some degree of genetic and phylogenetic determination of the motor patterns underlying feeding. We hatched ruddy turnstones Arenaria interpres in the laboratory from wild-collected eggs, and presented fully-grown birds with a variety of prey in order to elicit and document feeding mechanics. Kinematics of prey capture and handling were elucidated by frame-by-frame analysis of high-speed video footage of feeding birds. We documented that the eponymous rock-flipping behavior of turnstones is innate; na�ve captive birds turned over rocks and other objects, and did so prior to having ever found prey beneath any object. Surprisingly, the initial levering of objects off the substrate by turnstones was accomplished by a pattern of jaw-spreading similar in expression, but different in speed and amplitude, to that documented for surface-tension feeding in other Scolopacid sandpipers. Turnstones also use jaw-spreading when digging for invertebrates in sand, to break the eggs of other birds, and to enlarge the cracks made during egg breaking in a manner which improves their access to the contents of the egg. These observations raise the interesting possibility that jaw-spreading is a widespread, and perhaps basal, motor pattern that has been coopted for use in a variety of feeding contexts among the Scolopacid shorebirds.