AUGUSTA — Recently, a large number of finches have been reported sick or dead at feeders across southern and central Maine.
Contacts outside Maine, and even outside the Northeast, suggest that many other states are affected as well. Such widespread mortality at feeders is not uncommon this time of year but can be alarming to witness and has resulted in a large volume of calls to Maine Department of Inland Fisheries and Wildlife and to Maine Audubon as well as an influx of sick birds to local wildlife rehabilitators.
The cause of death, though no Maine specimens have been tested, is very likely to be salmonellosis, according to DF&W wildlife biologist Tom Hodgman. This gastrointestinal disease is caused by the bacteria salmonella. It leads to death most commonly in gulls and songbirds (especially finches) but also waterfowl and herons. Most reports currently in Maine are of affected pine siskins, with lesser numbers of American goldfinches and common redpolls.
Salmonellosis is commonly seen in late winter and early spring when three things work together to increase risk to birds at feeders. First, a winter’s worth of seed waste (and bird droppings) has accumulated on the ground under feeders. Throughout the winter, snow repeatedly covers these, limiting to some degree exposure to feeding birds.
Second, the weather in late winter and early spring results in melting conditions that exposes seed and bird waste. Furthermore, warm temperatures, especially in the debris under feeders, likely reach temperatures favorable for bacterial (i.e., salmonella) growth.
Third, wintering finches often arrive at feeders in great numbers, far more than can fit on a platform feeder or can perch on a tube-style feeder. The resulting “overflow” of birds land on the ground and sift through the seed waste under feeders looking for bits of food that have fallen from above.
Many birds suffering from salmonellosis appear “puffed out,” with their head down and eyes closed. Many will have no fear of humans and remain at the feeder while you approach. This behavior increases their vulnerability to predators, including pets.
Recently, cats known to have eaten infected birds became seriously ill and required veterinary care. It is important to keep cats indoors at all times and especially so during a salmonella outbreak. The family dog and even humans (especially children) can be exposed if they handle sick or dead birds. If you find dead birds at your feeder, it is recommended to place your hand in a plastic bag, pick up the bird, then invert the bag over the bird.
Bird and bag can be disposed of in domestic trash or the bird could be buried if the ground is not frozen. Do not simply discard the carcass where scavengers could find it, become infected and further spread the disease. Be sure to wash your hands after handling dead birds and bird feeders.
It is important at this time of year to break the salmonella “cycle.” To do so, a few steps can be taken to minimize future exposure.
First, bring your feeders in and wash them in a solution of 10 percent Clorox/90 percent water. Scrubbing with an old toothbrush is helpful. Allow the feeder to sit in the sun and thoroughly dry before reusing.
Second, and most importantly, clean up under the feeder. Rake up seed waste and dispose of in trash or bury it. If you reinstall your feeder, do so in another location to prevent birds from continuing to use the contaminated site.
Third, resist the temptation to feed during summer. This contributes to chronic salmonella infection (mildly affected birds that serve as carriers which can reinfect the population next winter) as warm temperatures and messy conditions under feeders during summer often lead to limited outbreaks in July and August.
Those who must feed during summer should do so over a paved driveway, brick walkway or other solid surface that can be swept clean regularly.
Fourth, begin feeding in fall once cooler temps have arrived and only use feeds that are preferred. Avoid using mixed seed where much of the millet and other seeds are not used and end up on the ground. Instead, feed only preferred items like black oil sunflower, suet and niger (thistle).
Additional resources to better understand this disease and others that affect birds at feeders can be found at the Web site for the Cornell University Laboratory of Ornithology: www.birds.cornell.edu/pfw/