bird migration

Tallying Bird Populations Then and Now

How many ducks and geese used the Estuary before the Gold Rush? The numbers are beyond conjecture, but they must have been mind-boggling. Observers writing about a hundred years ago noted major decreases during the era of market hunting, when waterfowl were shot to supply the restaurants and stores of California’s emerging cities, but offered no hard numbers. However, they recorded their observations of the abundance and seasonal presence of different species. Since then, government surveys, Audubon Society Christmas Bird Counts, and sport hunting records show a mix of change and continuity, with some duck species either scarce or common in the last century and now, and other common species becoming rare or vice versa. The US Fish and Wildlife...
Read More

Tracking Curlews Cross-Country

This winter, Jay Carlisle, director of the Intermountain Bird Observatory, teaming with Nils Warnock of Audubon Canyon Ranch and netting expert David Newstead of Coastal Bend Bays and Estuaries Program, caught two long-billed curlews and outfitted them with transmitters. Those birds may reveal where the wintering curlews on the California coast and Bayshore are coming from.“It’s such a habitat generalist that adapts well to humans,” Carlisle notes...
Read More

Tailing a Thrush

By Joe Eaton Researchers like Point Blue Conservation Science ecologist Tom Gardali have equipped Swainson’s thrushes, weighing just over an ounce, with tiny, one-gram GPS tags. If recovered, the tag shows the thrush’s exact winter destination, information vital to border-crossing conservation efforts. “You only get a few readings,” says Gardali, “and you still need to get the tag back. But GPS goes to a spot on the map. This is Holy Grail stuff.”  Sierra/Cascade thrushes were presumed to migrate to Mexico like their coastal cousins. When researchers included thrushes from Mount Lassen and Lake Tahoe in their GPS tracking, they learned otherwise. “The mountain birds are going from Mexico to Panama, possibly as far as Columbia.”
Read More