SURFACE-TENSION PREY TRANSPORT IN SHOREBIRDS - HOW WIDESPREAD IS IT

Surface tension prey transport is a feeding mechanism employing the su rface tension of water surrounding prey to transport prey from bill ti p to mouth, Previously, it has been demonstrated only in the Red-necke d Phalarope Phalaropus lobatus. On the basis of a model of the bill mo rphology necessary for this method of prey transport, I suggest that m any species of shorebird should be capable of surface tension feeding, Laboratory investigations of the feeding mechanics of Wilson's Phalar ope Phalaropus tricolor; Western Sandpiper Calidris mauri and Least Sa ndpiper Calidris minutilla demonstrated that all three use surface ten sion transport of prey when feeding in water, I examined interspecific variation in the performance of this feeding mechanism with a high-sp eed video system and a customized motion analysis system, Exploratory analyses indicated significant interspecific variation in distance the prey is transported per cycle of mandibular spreading, gape increase per unit transport, speed of transport, total number of cycles necessa ry to complete transport and total time to complete transport, The cal idrid sandpipers also occasionally used other feeding mechanisms in co njunction with surface tension transport of prey, The discovery that t hese sandpipers, which normally obtain prey by probing, are capable of surface tension transport of prey implies that the capacity to employ this feeding mechanism may be widespread in the Scolopacidae and may have been a significant factor in the evolutionary radiation of phalar opes into aquatic environments.