Seasonal distribution of waterbirds in relation to Spawning Pacific Herring, Clupea pallasi, in the Strait of Georgia, British Columbia

Abstract

About 3500-3700 waterbirds were present in 23 bays and beaches along 150 km of shoreline on the east coast of Vancouver Island, British Columbia prior to the arrival of Pacific Herring (Clupea pallasi). Waterbird abundance in the region increased to > 32 500 individuals when herring spawned in March with the greatest proportional increase occurring at the spawn site. Another 140 000 waterblrds were present outside the study site in deep water a few km offshore. Waterbird density in the entire study area increased from a low of about 66 birds/km2 prior to the arrival of herring to a peak density of about 616 birds/km2 when the herring spawned on the beaches.