Redpolls, other birds can catch diseases from feeders

Dead and dying redpoll birds are not a pretty sight, but that's what some folks are finding around their seed and suet feeders. Last week I wrote about two readers who contacted me about dying redpolls. One lives on Crow Wing County Road 25 and the other on White Sand Lake in Baxter.

Since then Carrie and John Guida of Nisswa, Sandre Strasser, who lives between Backus and Longville and Tom Rohlfs of Backus have contacted me and said that they, too, have dead redpolls. Tom also had a dead pine siskin.

In addition to their reports, they all had excellent questions. John asked, "Is it possible redpolls are becoming infected from bits of suet on the ground? Should we be feeding raw suet so close to the thistle feeder? Indeed, should we be feeding raw suet at all? Lastly, if raw suet is bad, would those bird blocks that one can buy "cooked" be a good substitute?

Sandy wondered if the birds should be turned in for analysis. The answer is no. If it's salmonella, what about transmission to pets and humans? What keeps the redpoll population in check? What preys on redpolls?

Tom wrote: "I have about 60 to 89 birds at my feeders now and about 90 percent are redpolls. I get all different types of birds throughout the year. I'm wondering if this will affect other birds this spring or summer."

These queries are all important and worth exploring, but first let's backtrack a bit.

In my last column I mentioned a rash of redpoll deaths in past years caused by salmonella. In addition, I noted two other potential culprits: aspergillus and E. coli. The latter was confirmed in redpolls found dead in Alaska.

After I wrote that column I received an e-mail from Carrol Henderson, DNR nongame wildlife supervisor, with an update on the situation. According to Carrol, similar die-offs are occurring from Michigan to New York and Vermont and south through Virginia and North Carolina. Some of the dead redpolls were turned in to the DNR's division of ecological services for analysis. It's been determined that the birds died from Salmonella B. This bacterial disease is transmitted by contact between birds, especially where they are concentrated at feeders. It may also be transmitted when droppings fall onto bird seed that is eaten by other birds. Redpolls, pine siskins and other northern finches should be migrating northward this month and the problem will subside as they disperse through northern woods for nesting.

Meanwhile, people who feed birds should consider cleaning under their feeders. Fallen seed could be contaminated. They also should take down their finch feeders for a week or two so birds are forced to feed over a larger area. Feeders should be washed and bleached and put out after redpolls have diminished. Carrol also cautions pet owners, whose cats can contract the disease by eating sickened birds.

Andrea Lee Lambrecht, naturalist and outdoor writer, can be reached at andreal@umn.edu.