Bacteria killing songbird species in Monterey County
Sickness related to salmonella has struck the creatures, threatening to end their song
MONTEREY » Birders across the Central Coast and all the way up into Oregon and Washington are lamenting the loss of thousands of Pine siskins, a small songbird belonging to the finch family that are dying in large numbers in the Monterey Bay Area from a bacteria that is spread through bird feeders.
And the backyard birders are not going to like the cure: They are being advised to pull down their feeders and stow them away until the end of this month and likely until the end of April until the siskins
disperse.
Beth Brookhouser, the vice president of marketing and communications for the SPCA Monterey County, said the birds are dying from salmonellosis, an infection caused by the bacteria belonging to the genus Salmonella.
It is a common cause of mortality in feeder birds, but the symptoms are not always obvious. Sick birds may appear thin, fluffed up, and depressed and may have swollen eyelids. They are often lethargic and easy to approach, which is not normal. Some infected birds may show no outward signs, but are carriers of the disease and can spread
the infection to other birds.
As much as backyard birders love the feeders, Brookhouser and other experts say the only way to curb the dieoff is to temporarily remove the feeders. It comes down to the birds congregating near each other, which is the catalyst for the spread of the bacteria. Once a bird is infected, it stands little chance of survival.
Infected birds shed the bacteria in their feces, and if they are frequenting a bird feeder, the surface of the feeder or the food itself is likely to become contaminated with their feces. In this way, the feeder
becomes a vector for the disease, spreading it to other birds. Pine siskins can be messy eaters, spraying seed on the ground where it becomes mixed with feces and becomes an additional source of infection.
While salmonellosis is particularly lethal for siskins, it can also infect other species of songbirds that hang out at feeders, such as lesser goldfinches. Siskins are small and heavily streaked on their breasts and have yellow-accents that typically appear on the ends of their wings and also on their tail feathers. But they are most eas
ily identified by the pronounced streaking, usually more visible than the streaking of other types of finches.
“In Monterey County, we noted a large influx of Pine siskins early in the fall with flocks exceeding 250 birds,” said Paul Fenwick, vice president of the Monterey Audubon Society. “It was not long after their arrival that we began to receive
inquiries from people who were discovering lethargic or puffed-up birds around their feeding station. I personally removed my feeders and water sources in December as a proactive move to prevent an outbreak in my neighborhood, but we have received reports of up to 30 or more birds perishing in a single yard over a 24-hour period in the Fisherman Flat area (Monterey) before the feeders were removed.”
Siskins are a migratory bird with an extremely sporadic winter range, ac
cording to the Cornell University Lab of Ornithology. They can overwinter from the Canadian border down into Mexico and from the Pacific shore to Cape Cod. They’ll summer in central Canada and up into Alaska. But they can also live yearround in a number of places in the west, including the Central Coast.
Siskins are not endangered. In fact, according to the Audubon Society, in the United States, there is an “irruption” taking place where flocks move southward into the U.S. during
years when there is a shortage of food in their home range in Canada.
A video produced by My Backyard Birding shows how the illness affects siskins. It can be viewed at https://www.youtube.com/ watch?v=ik5rNZFhT7E.