In Northern California and around the world, thousands of bird enthusiasts are bundling up, grabbing binoculars and heading outdoors to count birds at the crack of dawn.
The Audubon Society's 114th Christmas bird count is midway through its annual three-week run, but early reports indicate that some birds are shunning California, likely because of drought conditions and unseasonably warm weather.
Of all the factors that can affect bird numbers, "water is certainly the most important," said Garrison Frost, director of marketing and communications at Audubon's San Francisco offices.
Volunteer "citizen scientists" in Oakland, the Central Valley, and Lake and Mendocino counties have reported that the numbers of waterfowl, shore birds and some others appeared to be down so far during this year's Christmas bird counts, held Dec. 14 through Jan. 5.
Those and other birds like to feast on the plants, insects and other creatures that are nurtured by water, Frost said. If there's a shortage of food, they won't stop by, he said.
In Mendocino County, there was no shortage of bird species — 129, about average — during the Peregrine Audubon Society's Ukiah-area count, held Dec. 14, said Bob Keiffer, a board member and superintendent of the University of California's Hopland research and extension center.
But bird counters reported seeing fewer waterfowl, including scaup, a diving duck that normally is plentiful, he said.
Keiffer said unseasonably mild weather could be a factor. There haven't been enough heavy storms to push all the birds south from their summer homes, he said.
"They only go as far as they have to," he said.
Darlene Hecomovich, who organizes Lake County's Redbud Audubon Society Christmas bird counts, agrees. "As long as there's food where they are, they don't want to move," she said.