Distribution of Xantus' Murrelet Synthliboramphus hypoleucus at sea in theSouthern California Bight, 1995-97

We radiomarked 153 Xantus' Murrelets Synthliboramphus hypoleucus captured a l;sea near Santa Barbara Island (SBI), the largest; murrelet colony in the California Channel Islands, USA. We tracked these radiomarked murrelets in the Southern California Bight (SCB) aff coastal southern California during the 1995-97 breeding seasons. In 1995 during mild El Nino conditions, the m urrelets were distributed in non-upwelling areas. In 1996-97, they were dis tributed in dense patches, aggregating in cool upwelled waters near the nor thern Channel Islands or south of San Nicolas Island. Murrelets flew longer distances from SBI to foraging areas in 1997 ((x) over bar= 111 +/- 44 km) than in 1996 ((x) over bar= 62 +/- 25 km), but the distances they travelle d did not differ between months (Apr and May) within years. Mean foraging d istances fi om SBI were similar for 'incubating' murrelets (determined on t he basis of repeated visits to SBI) and 'non-incubating' murrelets during t he colony attendance period. We attributed the law return rate of radiomark ed murrelets to SBI to the capture and marking of a large proportion of bir ds that were not actively incubating rather than to any adverse effects of radio attachment. We believe changes in murrelet foraging patterns between the 1970s and 1990s are associated with changes in prey resources in the SC B. Flexibility in the foraging strategies of these murrelets may be related to the highly variable marine environment at the southern end of the Calif ornia Current Upwelling System.