Monitoring Migrating Shorebirds at the Tofino Mudflats in British Columbia, Canada: is Disturbance a Concern?

The Tofino Wah-nah-jus Hilth-hoo-is Mudflats on Vancouver Island, British Columbia, Canada, include both pristine areas and sites with residential and resort development. Shorebird counts were conducted at six sites around these mudflats in 2011 and compared with historical counts from 1988, 1989, and 1995. Temporal trends of counts did not vary among sites with different levels of disturbance. Over the entire mudflats, counts of Dunlin (Calidris alpina) moving northward had a negative trend over time (βyr = -0.04), as did counts of Western Sandpiper (Calidris mauri; βyr = -0.04), Least Sandpiper (Calidris minutilla; βyr = -0.03) and Short-billed Dowitcher (Limnodromus griseus; βyr = -0.04) moving southward. In contrast, counts of Black-bellied Plover (Pluvialis squatarola; βyr = 0.03) and Semipalmated Plover (Charadrius semipalmatus; βyr = 0.02) moving northward increased over time. Counts of Dunlin and Short-billed Dowitcher were lower at disturbed sites relative to non-disturbed sites, indicating that disturbance may be displacing birds away from some sites. Further, counts of northward migrating shorebirds were negatively correlated with the presence of people and dogs at the most disturbed site (Chesterman Beach). Monitoring and precautionary actions to address effects of disturbance at this important stopover site are warranted.