Tracking Canvasbacks Across the Seasons, Don Edwards San Francisco Bay National Wildlife Refuge, Fish and Wildlife Service

Kruse, Kammie and John Takekawa. 1998. Tracking Canvasbacks Across the Seasons. Tideline Vol 18 No. 3 1-3.

Tracking Canvasbacks Across the Seasons

by Kammie Kruse and John Takekawa

Photo by Leslie Day

It is a cold Nevada morning in early April. The sun is beginning to crest the snow-dusted peaks to the east of the Ruby Valley, and steam is rising off the blue pools within the bulrush-covered marsh. Through the quiet dawn in the rosy light, an eerie croak is reverberating from the distance. Increasing in volume as we wait, the strange call sounds like a soft growl from a cat, but it arose from the water’s surface. Emerging slowly from the morning mists, a red-headed duck with a long bill and white back swam slowly toward us, courting its mate. A pair of canvasbacks has come home to nest...

The canvasback (Aythya valisineria) is one of the largest and fastest flying ducks in North America. In flight, the male exhibits the most white of any duck and is very distinct with its “canvas” colored back, chestnut-red head, elongated black bill, and blood-red eyes. The female has the same elongated bill, but its head is buffy with brown eyes, and its body is brown. For the past 25 years, the continental population of canvasbacks has fluctuated around 580,000 individuals, with 25% of that population in the Pacific Flyway. San Francisco Bay estuary has historically supported the largest wintering numbers in the flyway.

Why are we concerned about this species? More than 60,000 canvasbacks were

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Last updated: May 22, 2008

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