Coastal waterbird population trends in the Strait of Georgia 1999–2011: Results from the first 12 years of the British Columbia Coastal Waterbird Survey

Tara Crewe1, Karen Barry2, Pete Davidson2,3, Denis Lepage1

1Bird Studies Canada – National Headquarters, PO Box. 160, Port Rowan, Ont. N0E 1M0
2Bird Studies Canada – British Columbia Program, 5421 Robertson Road, RR1, Delta, B.C. V4K 3N2; e-mail:
3Corresponding author

Abstract: The British Columbia Coastal Waterbird Survey is a citizen science long-term monitoring program implemented by Bird Studies Canada to assess population trends and ecological needs of waterbirds using the province’s coastal and inshore marine habitats. Standard monthly counts from more than 200 defined sites within the Strait of Georgia were analysed using route-regression techniques to estimate population indices and assess trends in 57 waterbird species over a 12-year period spanning the non-breeding periods from 1999–2000 to 2010–11. A power analysis was also conducted to validate the rigor of the survey design. Results indicate that the survey is detecting annual changes of 3% or less for populations of 29 waterbirds of a wide variety of guilds. Thirty-three species showed stable populations or no trend, 22 species showed significantly declining trends, and just three species showed significant increasing trends. We evaluate these results in the context of other long-term monitoring initiatives in the Salish Sea, highlighting specific birds to watch from a conservation perspective. Among those that showed a declining trend were a guild of piscivores, including Western and Horned Grebes, Common, Red-throated and Pacific Loons, and Rhinoceros Auklet; several sea ducks (Black and White-winged Scoters, Long-tailed Duck, Barrow’s Goldeneye, Harlequin Duck); two shorebirds (Dunlin, Surfbird); and Great Blue Heron. In the stable/no trend group were 20 species for which the Salish Sea is of recognised global or continental conservation importance, including one grebe, two cormorants, eight waterfowl (including five diving ducks), three shorebirds and two gulls. Next steps in the application of the B.C. Coastal Waterbird Survey and related datasets to conservation and research management questions are discussed, underscoring the importance of continued monitoring using this cost-effective approach and expanding the use of these data to hypothesis-testing to investigate factors potentially driving population changes.

Keywords: British Columbia, Citizen Science, coastal, monitoring, overwintering, Pacific, population trends, waterbirds, waterfowl.

PDFicon Crewe, T., K. Barry, P. Davidson, and D. Lepage. 2012. Coastal waterbird population trends in the Strait of Georgia 1999–2011: Results from the first 12 years of the British Columbia Coastal Waterbird Survey. British Columbia Birds 22:8-39.


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