SAN FRANCISCO -- Scientists are stumped about why thousands of rare seabirds are suddenly being spotted on land in Northern California.

The small birds, called red phalaropes, live many miles off the Pacific coast and usually only land in the Arctic, where they breed and raise their young.

But bird enthusiasts began spotting the birds in Sonoma County on Christmas Day, and flocks have since been reported in residential neighborhoods in San Francisco, Palo Alto and Los Gatos, among other areas. The largest sighting was a flock of 1,200 near Half Moon Bay.

Scientists said many of the birds are emaciated and weak from flying in strong ocean storms, which may have pushed them onto land to look for food. Some have fallen victim to predatory cats and gulls, while others have reportedly been struck and killed by drivers along Highway 1.

The sightings come as birders from around the San Francisco Bay area conduct the annual Christmas Bird Count, an annual census of individual birds in certain neighborhoods.