Figure 2. Aerial view of the California Channel Islands looking west across Anacapa toward San Miguel in the background.

Some of my preliminary results indicate radio-marked parents foraged in similar areas during each year of the study, generally within 40 km of the Prince Island colony, aggregating over insular shelf waters near the southern rim of the Santa Barbara Basin and occasionally in deeper basin waters (> 200 m). Despite this spatially persistent foraging area, the composition of prey delivered by parents to nestling auklets was highly variable temporally, both within the breeding season and among years.
Adults provisioned nestlings, primarily with euphausiids (Thysanoëssa spinifera and Euphausia pacifica), age-0 fishes (pleuronectids, rockfishes, and anchovy/sardine), and small amounts of cephalopods (Loligo opalescens, and Octopus spp.). Despite large seasonal and interannual variation in prey species composition, nightly meal-load mass, nestling mass gain, pre-fledging mass, and fledging success also did not differ among years. My results demonstrate that even though parents foraged in similar areas,
hypothetically, dietary composition is largely due to variable oceanographic conditions. Further, diet composition had little influence on auklet fledging success, probably because their main prey items during each year were similar in caloric content, or displayed variability in species-specific availability to foraging parents. I am currently working with describe important auklet habitats within their foraging area using digital bathymetry, and satellite-sensed SST and ocean color (surface chlorophyll a concentration).