In 1999, during La Niña conditions in the northeastern Pacific Ocean, I collected a remarkable dataset from 20 April – 5 June, beginning in the Galapagos Islands, Ecuador (0.72° S; 90° W) and ending in Bamfield, British Columbia, Canada (48° N; 124° W). For 47 days, I documented all marine birds along a south-to-north 9,000 km transect, as well as the occurrence of marine debris, physical evidence of convergence zones, and marine mammals.
In collaboration with David Hyrenbach to analyse the data, we assessed the composition of the seabird community in relation to remotely-sensed water mass properties and wind conditions. We found three distinct marine bird communities along the transect: tropical (booby-tropicbird-frigatebird), subarctic (alcid-fulmar) and a widely-distributed cosmopolitan assemblage dominated by tubenoses (albatrosses, shearwaters, and storm-petrels). These communities inhabit distinct regions of the Pacific Ocean, characterized by distinct water mass properties.
We noted a marked change in species composition at approximately 20° N, with a shift from the tropical to the subarctic community. Our results underscored previous evidence of spatial segregation of marine bird species distributions and feeding guilds across the Northeast Pacific Ocean. Additionally, our study provided an unusual opportunity to survey pelagic seabird distributions, within a poorly studied region, during an anomalous year.
This research highlighted the continued importance of ocean exploration and standardized time series for the study of seabird biogeography. We encouraged other investigators to retrace this survey track in the future. This research was published in Marine Ornithology and presented at conferences in Canada and USA.