Summer movements of marbled murrelets from Canada to Alaska

Abstract

Knowledge of seasonal marine bird migration patterns is required to inform marine bird conservation and management efforts. We deployed solar-powered satellite transmitters to track the movements of threatened marbled murrelet Brachyramphus marmoratus during the breeding and post breeding periods. We tagged birds (n = 27) in British Columbia (BC), Canada, over 3 years (2014-2016) from 3 different marbled murrelet conservation regions as defined by the species’ recovery strategy. Of 4 tagged birds which provided movement data for more than 57 d, 3 (1 in each year) revealed long-distance movements from BC to Alaska, USA, during breeding or post-breeding periods. The 3 birds which moved northward originated from the 3 different conservation regions. We found limited support for the concept that birds tracked cooler waters as they headed northward. One bird remained in unusually warm waters near the capture sight in Desolation Sound in 2016. Importantly, the arrival of BC birds in Alaska during summer could contribute to at-sea survey estimates of marbled murrelet abundance during the Alaska breeding season, and their occcurence in Alaska has implications for BC populations with respect to anthropogenic threats in the marine habitat, including the potential for incidental take in gillnet fisheries and risks from oiling. Our results demonstrate connectivity between BC and Alaska marbled murrelet populations. Overall, tracking duration was relatively short, and locations were confined to the deployment areas in BC. Our results indicate capture and tagging impacted study individuals and may have contributed to increased mortality. Our research, coupled with that of others, suggests that long-distance northerly migrations patterns may not be unusual in Brachyramphus murrelets.