Fire-stricken birds are fleeing the smoky North Bay. Here's where they're roosting.

A bird rests on a tree during a wind-driven wildfire in Malibu, California, October 22, 2007. Birds fleeing the North Bay fires that started on Oct. 8, 2017 have come to roost in surrounding cities, experts say. less A bird rests on a tree during a wind-driven wildfire in Malibu, California, October 22, 2007. Birds fleeing the North Bay fires that started on Oct. 8, 2017 have come to roost in surrounding cities, experts ... more Photo: MARIO ANZUONI Photo: MARIO ANZUONI Image 1 of / 39 Caption Close Fire-stricken birds are fleeing the smoky North Bay. Here's where they're roosting. 1 / 39 Back to Gallery

Birds, their feathers dusted with ash and their lungs choked by smoke, are turning up in Bay Area parks and backyards in droves as wildfires continue to sizzle across Northern California, experts say.

"I've seen a lot more hillside birds coming down from the fires and moving into East Bay cities," said Andrew Ford, a Martinez-based wildfire biologist. "Birds I wouldn't normally see in such high numbers."

Don't expect any rare bird sightings, Ford said, but you can look forward to higher volumes of species that have fled the North Bay like vireos, lesser goldfinch, morning doves and scrub jays. It will likely take a few weeks before data from regional banding sites can confirm Ford's anecdotal findings, but biologists from the Audubon Society and San Francisco Bay Bird Observatory also claim to have noticed the trend.

The birds that survived the initial outburst of flames have other dangers to contend with now, Ford notes, namely the thick smoke that has floated south from the Wine Country and blanketed surrounding regions.

Avians are circular breathers, explained Amber Engle, wildlife rehabilitation manager at Lindsay Wildlife Experience, and smoke can suffocate their delicate lungs.

"Birds are more sensitive to it [than humans] because they have a more extensive respiratory system," Engle said. "They have to move so much oxygen throughout their bodies to fly."

Thus, it's ostensible that a suffocated bird may drop to earth, Ford said, having suffocated mid-flight from the ash-flecked air.

Navigating fuzzy skies poses problems for birds' navigation systems, too, because the gray smoke can block out the sun and cloud their vision. This can prove a challenge for predators, like raptors, that case the ground for prey and birds in the midst of migrations.

"It's an important migration time for the birds so my question is what are the migratory birds doing that normally migrate to the North Bay?" said Yiwei Wang, executive director of the San Francisco Bay Bird Observatory. "Will there be any differences or changes in their journeys?"

Many questions remain up in the air, but humans shouldn't excessively worry for the Bay Area's airborne animals, at least in the short term.

All of the biologists SFGATE spoke to stressed that wildfires are often a positive force for forest-dwelling creatures, diversifying the landscape and enabling new outgrowth. At least that's been the narrative for the last few decades.

With global warming, says Andrea Jones, Audubon Society's director of bird conservation, the story might be changing.

"We're going to have to rethink the way we look at fires," she said. "It may not always be positive. We're getting these absolutely gigantic fires, and it's not yet certain how they will impact the landscape and wildlife."

Read Michelle Robertson’s latest stories and send her news tips at mrobertson@sfchronicle.com.