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Abstract

Understanding the movements of seabirds, which are important ecological indicators, can provide new insights into physical and biological aspects of the marine environment. This information can also be used in planning marine conservation and oil spill response strategies. Though Black Guillemots Cepphus grylle are widely distributed in the coastal waters of eastern and arctic Canada, little is known about their movements during the non-breeding season. We used a combination of global location sensors and stable-isotope analyses on Black Guillemots breeding on Country Island, Nova Scotia, Canada and on Kent Island, New Brunswick, Canada to examine their non-breeding movements and trophic ecology in 2017–2018. Overall, the two populations dispersed an average of 157 km from their breeding colonies (max. 494 km) throughout the region, reaching areas that included the Scotian Shelf, Gulf of St. Lawrence, Bay of Fundy, and Gulf of Maine; both populations overlapped in the Bay of Fundy during the winter. Trophic levels (δ15N) and foraging locations (δ13C) differed between the colonies. Birds from Country Island foraged at higher trophic levels and in less benthic waters than Kent Island birds overall, and birds from both colonies foraged at higher trophic levels in autumn than in winter. This indicates that foraging strategies differ between Black Guillemot populations and that diet varies between seasons, even when foraging habitats do not. Our findings, combined with other seabird, fish, and marine mammal tracking studies, can inform marine management decisions in Atlantic Canada.

DOI

http://doi.org/10.5038/2074-1235.49.1.1399

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