Marbled Murrelets as Initiators of Feeding Flocks in Prince William Sound, Alaska

Abstract

-I sought to determine which seabird species initiated small, ephemeral, multispecies feeding flocks in Prince William Sound, AK (PWS). I observed 47 feeding flocks at five sites duringJune 1996 and determined the initiating species at 34. All of the latter flocks were initiated by pursuit divers, of which 76.5% were Marbled Murrelets (Brachyramphus marmoratus), the most abundant seabird in PWS. Formation of feeding flocks followed either of two scenarios: 1) larids were attracted to a feeding location by the presence or activity of Marbled Murrelets (26.9%), or 2) both larids and murrelets were present and flock feeding began after the murrelets dove from the surface (50.0%). Other principal participants were Black-legged Kittiwakes (Rissa tridactyla) and Glaucous-winged Gulls (Larus glaucescens). Received 14 April 1999, accepted I June 1999.