Laura Erickson's For the Birds

Bird diseases II

Last week I reported on a Birds in the News that a sad number of redpolls, siskins, and goldfinches were dying at people’s bird feeders. On Wednesday, there was a post on the Minnesota bird chat Internet listserves from Sharon Stiteler about some birds that Minnesota DNR Nongame Wildlife Program Supervisor Carrol Henderson had had necropsied. Sharon wrote, “The early tests on the redpoll carcasses had suggested that the redpolls and siskins were dying of something viral not fungal, however the tests have concluded that the redpolls died of Salmonella E.

‘’This outbreak of salmonella is widespread with reports of dead birds from several areas including Minnesota, Vermont, Virginia, Michigan and Quebec just to name a few.

Sharon continues, ‘’One of the ways birds are probably spreading it is through fecal material built up around feeding areas. The best thing to do when this occurs is remove finch feeders and thoroughly clean them. It is also a good idea to keep the feeders in for a week to encourage the redpolls and siskins to move on to other areas and cut back on the chance of it spreading at your feeder. Also, it is important to clean up the area under the feeders as well.

‘’One one other note is that salmonella is transmittable to cats so if you have a problem with a neighbor’s cat at your feeder, you might want to warn them to keep their cat indoors for a week (or preferably the rest of the cat’s life).’‘

Sharon’s absolutely right about making sure your feeders are clean. Giving them a thorough brushing in soapy water, then soaking them briefly in a solution of water and household bleach, rinsing and allowing them to dry out overnight is a good way of making sure they’re germ free. But overall, I suspect that hanging feeders aren’t nearly as dangerous for disease transmission as platform feeders with wood bottoms (many are now made with screened bottoms to allow rainwater and melted snow to drain quickly) or the ground itself, where seeds collect. Common feeder diseases are most easily spread, and thus most prevalent, among ground-feeding birds. Especially vulnerable are little birds where Rock Pigeons proliferate, because they can harbor a great many pathogens in their droppings. So making sure to clean up the ground in big finch years is a great idea.

Of course, like anything edible, bird seed itself can be a hotbed of fungus and bacteria, especially when it gets moist. I’ll never understand why manufacturers of tube feeders make the tubes extend lower than the lowest feeding ports or holes, since there’s no way the seed below those holes can possibly get eaten. Whenever I fill my thistle feeders, I first empty out all the contents out on the snow for the finches to finish, unless the seed inside is wet—in that case I throw it out. I only offer suet at all when there are lots of finches to eat it—otherwise, they’re stuck with sunflower like everyone else, and I never offer that in tube feeders. When I empty my thistle feeders, I try to pour the seed in different places in the yard, so the birds won’t gather in a few places all the time—I’m hoping that helps protect them.

When birds first ingest Salmonella, it takes a while for them to get sick, and meanwhile they can move to new areas, so if you do discover a sick or dead bird, it wasn’t necessarily your feeder that caused the illness. But because Salmonella is so easily transmitted among ground-feeders, it’s important to keep the disease from spreading. If I found a sick bird, I’d close up shop for two weeks to prevent healthy birds from gathering where they could possibly pick up the sickness. It’s lovely to invite birds to our yards to dine. But as with any company, shouldn’t we make sure the table’s cleaned at least once in a while? http://www.dnr.state.mn.us/ecological_services/nongame/index.html