Over Ocean Flocking

Over the past two decades, we have observed a dramatic increase in over-ocean flocking by wintering shorebirds at Boundary Bay, near Vancouver, BC. We believe this functions as an anti-predation strategy during high tides. To view a short video exploring this behaviour by large flocks of wintering Dunlin click here.

Major aspects of work by the CWE on shorebirds:

• feeding-predation danger tradeoffs, particularly at migratory stopover sites
• migratory connectivity using stable isotopes, trace elements, and genetics and morphology
• breeding biology in Alaska
• field studies on the wintering grounds in Colombia and Peru
• diet, particularly adaptations to feeding on biofilm
• modeling migration strategies
• documenting and explaining differential migration distribution of age and sex classes during the non-breeding season

One emerging general theme in this research is how birds balance the tradeoff between foraging effort and the risk of predation, particularly by migratory falcons. The return of falcons to the landscapes of both the Americas and Europe over the past 20 years have substantial implications for their prey. We have evidence of changes in habitat utilization during migration, with decreased usage of riskier stopover sites in favor of larger more open sites, despite apparently poorer feeding at the larger sites. Such habitat shifts, if general have substantial implications for the shorebird population monitoring schemes and the detection of long-term population trends.

For more information on current work being done by CWE researchers on shorebirds, contact David Lank or Ron Ydenberg.

Centre for Wildlife Ecology, Dept. of Biological Sciences, Simon Fraser University, Burnaby, BC CANADA V5A 1S6