Conditions in Alaska, USA, pose a challenge for monitoring populations of Brachyramphus murrelets using standard survey methods, because of strong winds, 2 sympatric species, short nights, and variable nesting habitat. We tested 3 methods for monitoring Brachyramphus murrelets breeding in the Kodiak Archipelago, Alaska, in 2010-2012. In addition to standard audio-visual and radar methods, we tested-for the first time with murrelets in Alaska-the application of autonomous acoustic recorders for monitoring vocal activity. We completed 74 radar, 124 audio-visual, and 134 autonomous acoustic surveys, focused on presunrise activity peaks; this yielded 26,375 murrelet detections. Marbled (B. marmoratus) and Kittlitz's murrelets (B. brevirostris) could not be distinguished using combinations of radar and acoustic recordings; therefore, at-sea surveys will be required to determine localized species proportions. Of the 3 methods, radar sampled the largest area and detected silently flying murrelets, providing the most reliable data on local populations; however, radar identification of murrelets was unreliable in winds exceeding 18 km/hr. Audio-visual surveys were useful for species identification and to document behaviors associated with local nesting, whereas autonomous acoustic recorders allowed season-long monitoring of murrelet vocal activity. Within potential forest-nesting habitat of marbled murrelets, all 3 methods gave similar measures of presunrise murrelet activity, but only radar reliably sampled murrelets commuting between nest and ocean. Because of their low cost and flexible programming, automated sound recorders offer an affordable way to sample vocal activity prior to more intensive or expensive radar and audio-visual surveys. We recommend that population monitoring and habitat studies of Brachyramphus murrelets in Alaska include combinations of all 3 methods. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.
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.
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