DIET OF XANTUS'S MURRELETS IN THE SOUTHERN CALIFORNIA BIGHT

Most of what is known about diet of Xantus's Murrelets (Synthliboramphus hypoleucus) comes from prey found in 19 of 22 murrelet stomachs collected during the 1977 breeding season near Santa Barbara Island in the Southern California Bight (SCB). In May 2002, we examined stomachs of 10 Xantus's Murrelets collected near Anacapa Island, also within the SCB. Seven of the 10 stomachs contained prey. Prey were subadult or adult northern anchovy (Engraulis mordax; 2 stomachs), either juvenile bluefin driftfish (Psenes pellucidus) or medusafish (Icichthys lockingtoni; 2 stomachs), and euphausiids (Thysanoessa spinifera; 3 stomachs). Only one prey type was found in each stomach. Our sample added to the diversity of known prey types used in the SCB, including euphausiids and larger age/size classes of fish. We confirmed continued use of northern anchovy, and identified new prey species (bluefin driftfish or medusafish) associated with jellyfish or floating algae and debris in convergence lines. During the breeding season, Xantus's Murrelets appear to be generalist feeders that search for and use available prey that may be concentrated at convergence lines.