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Shearwaters in the Northern California Current: Combining Environmental Predictors with Satellite Telemetry and At-Sea Abundance

Released: 2017
Adams, J., J.J. Felis, M. Czapanskiy, J. Schulien, B. Henry. 2017. Shearwaters in the Northern California Current: Combining Environmental Predictors with Satellite Telemetry and At-Sea Abundance. Pacific Seabird Group 44th Annual Meeting, Tacoma, WA. 22-25 February 2017.

Where seabirds are of concern, Marine Spatial Planning can benefit if telemetry data can be used to improve seabird abundance estimates at sea in areas not surveyed directly. Here, we combine traditional vessel-based surveys of seabird density at sea with measures of individual space-use derived from telemetry. We used aerial survey data and satellite telemetry to compare at-sea habitats and environmental factors influencing the non-breeding distribution and abundance patterns among non-resident Pink-footed (PFSH, Ardenna creatopus) and Sooty (SOSH, A. grisea) shearwaters. These two congeners occupied different habitats at sea. PFSH abundance was greater in fall compared to summer, and was usually concentrated over outer continental shelf and slope waters. SOSH was the most abundant species in summer and second most abundant in fall. In June 2011, SOSH were most abundant over inner-shelf and slope waters; most were observed over shelf waters off Washington and over slope waters off northern Oregon. Fewer SOSH were observed in July 2012 than in June 2011 and average densities were less. Models to predict SOSH abundance indicate substantial interannual variability in habitat-use, and seasons within years were more similar in model form. In 2011 (June & October), SOSH abundance related to oceanography (plume & upwelling shadows, warmer SST, fronts, and chlorophyll; in 2012 (July & September), abundance related to geography and low chlorophyll persistence. PFSH abundance in fall was less related to oceanographic variables, but had strong relationship with the shelf-break. The addition of satellite telemetry-derived space-use improved models used to predict abundance patterns at sea.

This product is associated with the following project:
Tracking the Movements and Migrations of California Current Seabirds

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