Bacterial disease not completely gone, but North Bay bird feeders can go back up, officials say

Bird lovers have been waiting for months now for word that it’s safe to rehang and refill their feeders after a highly contagious bacterial disease killed untold thousands of songbirds over the winter and early spring.

But while the reported incidence of salmonellosis has declined substantially in recent weeks, a dying bird found in Sonoma County within the past 11 or 12 days suggests anyone deciding to feed the birds in their area should proceed with caution, experts say.

That means keeping a vigilant eye out for signs of ill health or mortality among the birds around one’s home and maintaining a regular cleaning schedule that includes using bleach to sanitize bird feeders, they said.

“It’s still out there, gosh darn it,” said Veronica Bowers, director and founder of Native Songbird Care & Conservation in Sebastopol, which received a sick pine siskin found in Cotati on May 2. It died a few hours later, she said.

“The main thing,” said Alison Hermance, communications manager at WildCare in San Rafael, “is the salmonellosis has not really left. It’s the birds who are most susceptible who have mostly moved on.”

The disease is caused by salmonella, a common gut bacteria that poses little danger to most bird species, which carry it asymptomatically.

For reasons still unknown, tiny pine siskins, members of the finch family, are especially susceptible. Once infected, they quickly become underweight, grow weak, develop labored breathing and a fluffed-up or ruffled appearance, and usually die within 24 hours, said Krysta Rogers, a senior environmental scientist with the California Department of Fish and Wildlife.

Pine siskins breed in the boreal forests of Canada, and winter in California and other parts of the United States. They are common at bird feeders, where sick birds easily pass on the bacteria through their feces to other feasting birds.

The birds were especially abundant this year but by late November and December were turning up weak and dead around the greater Bay Area, Central Coast and Sierra Nevada, Rogers said.

State Fish and Wildlife received reports of more than 2,420 dead birds, mostly pine siskins, including about 260 in Sonoma County, mostly around the time of an agency news release in February, Rogers said. But that doesn’t count what could be tens of thousands that were never seen and never reported.

The birds have mostly migrated back north, though a few dawdlers have still come in, Rogers said.

In addition, there have been cases in house finches and goldfinches, though they also are vulnerable to avian mycoplasmosis, another bacterial infection easily spread at certain kinds of feeders that causes conjunctivitis and upper respiratory symptoms, Rogers said.

“It’s just a crazy thing,” Bowers said, “and the problem now is that goldfinches and house finches are just as susceptible to it, and it’s the breeding season for them, so you don’t want parents out there becoming exposed and then passing it on to their young.”

Said Rogers, “There are many diseases we see circulating in wild birds at bird feeders, so it’s always important to remain vigilant and to keep the feeders and bird baths as clean as possible, cleaning them thoroughly at least weekly.”

Hermance, with WildCare, recommended using only plastic or glass feeders and soaking them weekly in a 10% bleach solution — 1 part bleach to 9 parts water — for 20 minutes, then drying them in the sun for additional disinfection. Having two bird feeders that can be swapped out weekly facilitates the cleaning, she said.

“You’re inviting them to feed at your house,” Hermance said. “You’d better make sure to keep your tables clean.”

You can reach Staff Writer Mary Callahan at 707-521-5249 or mary.callahan@pressdemocrat.com. On Twitter @MaryCallahanB.