The telephone calls and e-mails are still coming from people concerned about finding dead, dying and stressed-looking wild birds near their homes and feeders. And though I had only written about this topic less than two months ago, I think it's a good idea to visit the matter once again.
From the sounds of things, the problem has been fairly widespread. Articles have recently been printed in newspapers across the Northland describing salmonella poisoning in wild birds. While several species of birds have been reported to be dying from the bacteria, including purple finches, American goldfinches, and pine siskins, it has been mostly redpolls succumbing to the disease this past winter and early spring.
That said, no one with absolute certainty can diagnose the problem in any of these cases without first having the affected birds examined and tested in the laboratory. Nevertheless, the bacterium Salmonella is frequently the reason wild birds become sick and die during late winter and early spring around bird feeding stations. Unfortunately it's often people who enjoy feeding wild birds who unknowingly help spread the disease amongst a population of birds.
According to the United States Geologic Survey's "National Wildlife Health Center" Web page, salmonella infection can occur in all species of birds. However, "the outcome of infection depends on a variety of factors, including age, stress, host species susceptibility, and bacterial virulence."
Furthermore, "Salmonellosis is a common cause of mortality in birds at birdfeeders."
While salmonella is a normally occurring bacterium found in the gut of many different species of wild and domestic birds, it's usually because of limited food sources and concentrations of birds around available food - frequently exacerbated by severe winter weather - that lead to stress and, consequently, a bird's susceptibility to the disease.
Afflicted birds often appear lethargic with droopy heads, spread wings, puffed out feathers and labored breathing. They sometimes will have diarrhea and might look severely emaciated too. In most cases, diseased birds lose their natural fear of people and other animals. These sick and dying birds will appear very weak while sitting on the ground. If they can still fly, they will do so weakly and with difficulty, usually landing quickly after taking flight.
Salmonella outbreaks occur throughout populations of birds across the northern tier of North America. A major event happened during the severe winter of 1996-97 when the disease was witnessed in birds in all Canadian provinces and in 15 eastern and Midwest states. Smaller outbreaks of the disease are reported yearly and have also been documented in populations of house sparrows.
As I wrote recently, what do we do when we observe sick and dying birds around our wintertime feeders? Or, more importantly, wish to avoid seeing such birds? First and foremost, it's important to insure that our feeding stations don't become sources of infection. This can be accomplished by making certain that the birdfeeders we use to attract birds (as well as the ground below the feeders) are kept clean.
Secondly, be attentive about the condition of your seed. Don't feed damp or moldy seed. If your seed is stored inside the garage or some other building subject to temperature and humidity fluctuations, be sure to store your seed in weather and mouse-proof containers - how, where, and in what you store your birdseed inside of really matters.
Birdseed inside feeders, in addition to the residual seed that has fallen on the ground, becomes excellent sources for molds to grow and flourish on during periods of warm, damp weather. As well, contaminated bird feces can help spread the disease too. Thus, always keep your feeders and areas surrounding your birdfeeders clean. Clean your feeders, including birdbaths, and don't allow seed and feces to accumulate on the ground below or inside your birdfeeders and birdbaths.
Thoroughly sanitize your feeders and birdbaths from time to time with hot water and soap, followed by disinfecting them with a 10-percent bleach and water solution, especially if you feed birds in the wintertime or have observed sick and dying birds nearby. Also, if you don't feed birds in the summertime, remove and disinfect your feeders and put them away until you're ready to use them again.
When performing these vital birdfeeder and birdseed cleaning chores, protect yourself from possible contamination. Never wash your feeders or birdbaths inside your house; clean them outdoors. Wash your hands with soap and water and wear rubber gloves when handling feeders for cleaning purposes or when picking up dead or sick birds and old seed. And always dispose of used gloves, old seed and dead birds in a proper place to reduce the risk of spreading the disease.
I'm hopeful that the apparent salmonella outbreak in some of our populations of wild birds has about run its course. Spread of the bacteria can be greatly reduced by following sanitary feeding and cleaning practices at your backyard bird feeding stations. However, if an outbreak occurs, stop feeding birds altogether, take down and clean your feeders, and remove the discarded seed covering the ground.
Until next time, be sure to get out and enjoy the great outdoors. Spring is here.
(For more information related to bird diseases, including salmonella infection, visit the National Wildlife Health Center Web site at: www.nwhc.usgs.gov.)
Blane Klemek is the Bemidji area assistant wildlife manager, DNR Division of Fish & Wildlife. He can be reached at email@example.com.