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Abstract

Information on the distribution and abundance of marine birds is needed to evaluate current status in relation to threats from potential increases in vessel traffic off southern Vancouver Island, British Columbia (BC), Canada, in the Salish Sea. We conducted year-round boat based surveys in waters between Sidney, BC and Victoria, BC from November 2015 to August 2019 and examined seasonal variation in bird distribution and abundance. Our study area included parts of the Sidney Channel Important Bird Area, the Shoal Harbour and Victoria Harbour Migratory Bird Sanctuaries, and the Chain Islets Ecological Reserve, adjacent to major shipping lanes, as well as ports and marinas. With the approval for the proposed expansion of the Trans Mountain pipeline to Burnaby, BC, tanker traffic is expected to increase in our study area. Increases in several categories of marine vessel traffic have occurred recently in the Salish Sea and are expected to increase further with the development of Liquefied Natural Gas projects and the Delta Port expansion on Roberts Bank. Within that context, we counted all marine birds but focused primarily on alcids: Rhinoceros Auklet Cerorhinca monocerata, Common Murre Uria aalge, Pigeon Guillemot Cepphus columba, Marbled Murrelet Brachyramphus marmoratus, and Ancient Murrelet Synthliboramphus antiquus. Alcids were present year-round but showed species-specific seasonal spatial patterns. These patterns are likely related to seabird annual cycles as well as fluctuations in forage fish prey populations, their habitats, and variation in seasonal availability to birds. Increasingly busy shipping lanes for tanker, cargo, and passenger vessels pass nearby and through our study area. These shipping lanes, together with traffic from tugs, fishing vessels, and recreational motor and sailing vessels, plus the many marinas and terminals in the area, pose significant risks to marine birds.

DOI

http://doi.org/10.5038/2074-1235.51.2.1536

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