PREY SELECTION OF A CAPTIVE OYSTERCATCHER HAEMATOPUS-OSTRALEGUS HAMMERING MUSSELS MYTILUS-EDULIS FROM THE VENTRAL SIDE

We studied prey choice of a captive Oystercatcher:hat hammered Mussels from the ventral side. The results replicate previous findings that v entral hammerers select Mussels of intermediate size, select against t hick-shelled Mussels, abandon an increasing proportion of Mussels with increasing size and do nor pick up Mussels covered with barnacles. Ab andoned Mussels had thicker shells than Mussels that were successfully opened, but part of the selection against thick shells seemed to occu r before the Mussels were picked up. Barnacles could not serve as cue for this. In fact, it remains unclear why ventrally hammering Oysterca tchers ignore Mussels covered with barnacles.