The National Audubon Society relies on volunteers every year to track bird populations across the country. In Oakland, human participation stayed strong; the birds just weren't there, SF Gate reported.

Called the Christmas Bird Count, the project is in its 114th year. The society credits the "citizen-count" for revealing species in decline, according to its website. A collection of past reports has helped identify 64 species currently on Audubon's watch list. More could be added if Oakland's data persists.

"Normally we'd see thousands of scaup and bufflehead and canvasback. This year it's staggering - we've hardly seen any," said Ruth Tobey, one of over 200 volunteers who tracked birds in the the East Bay on Sunday.

It's early to pinpoint the exact reason for the area's low numbers (the count only began on Saturday and official numbers don't reach the public until Jan. 5, when the event ends), though all the usual factors are being considered, such as drought, the recent cold weather, pesticides, and climate change, among others, according to SF Gate.

"It's like going back to summer camp to see your old friends, but suddenly your friends aren't there," she said. "It's a serious disappointment. But that's why we're here - to record the shifts and changes, for better or worse."

"This is really citizen science," said David Rice, a psychologist from Berkeley who noted the ArrowHead Marsh in Oakland at least looked cleaner even if it wasn't supporting as many birds. Conservation efforts to protect the marsh can be credited to the Audubon society and its band of volunteer scientists, according to SF Gate. "It's not about counting rare birds; it's about counting all birds. This way you can pick up changes in populations and try to see the big picture," rice added.

Of course, bird watchers aren't only it for the numbers, but for the chance to spot a rare species. According to SF Gate, the most exotic find was a redstart warbler, which normally live in southwestern deserts.