Geolocator tagging links distributions in the non-breeding season to population genetic structure in a sentinel North Pacific seabird.

We tested the hypothesis that segregation in wintering areas is associated with population differentiation in a sentinel North Pacific seabird, the rhinoceros auklet (Cerorhinca monocerata). We collected tissue samples for genetic analyses on five breeding colonies in the western Pacific Ocean (Japan) and on 13 colonies in the eastern Pacific Ocean (California to Alaska), and deployed light-level geolocator tags on 12 eastern Pacific colonies to delineate wintering areas. Geolocator tags were deployed previously on one colony in Japan. There was strong genetic differentiation between populations in the eastern vs. western Pacific Ocean, likely due to two factors. First, glaciation over the North Pacific in the late Pleistocene might have forced a southward range shift that historically isolated the eastern and western populations. And second, deep-ocean habitat along the northern continental shelf appears to act as a barrier to movement; abundant on both sides of the North Pacific, the rhinoceros auklet is virtually absent as a breeder in the Aleutian Islands and Bering Sea, and no tagged birds crossed the North Pacific in the non-breeding season. While genetic differentiation was strongest between the eastern vs. western Pacific, there was also extensive differentiation within both regional groups. In pairwise comparisons among the eastern Pacific colonies, the standardized measure of genetic differentiation (FꞌST) was negatively correlated with the extent of spatial overlap in wintering areas. That result supports the hypothesis that segregation in the non-breeding season is linked to genetic structure. Philopatry and a neritic foraging habit probably also contribute to the structuring. Widely distributed, vulnerable to anthropogenic stressors, and exhibiting extensive genetic structure, the rhinoceros auklet is fully indicative of the scope of the conservation challenges posed by seabirds.

Beach-cast debris surveys on Triangle Island, British Columbia, Canada indicate the timing of arrival of 2011 Tohoku tsunami debris in North America.

We conducted beach-cast debris transect surveys on Triangle Island, British Columbia, Canada in 2012-2017 to (1) establish a baseline against which to track future changes in stranded debris on this small, uninhabited island; and (2) time the arrival in western North America of debris released by the 2011 Tohoku tsunami. Most (90%) of the six-year total of 6784 debris items tallied was composed of Styrofoam or plastic. The number of debris items peaked in 2014 (waste Styrofoam, rope) and 2015 (waste plastic, wood), and cumulative totals for all debris types were ca. 50% higher in 2014-15 than in 2012-13 and 2016-17. The peaks in 2014-15 probably represented the arrival of the bulk of the tsunami debris, based on close correspondence with forecasting models and debris surveys elsewhere. A fuller understanding of the movement of the Tohoku tsunami debris will require information from other beach monitoring programs.