For as long as I can remember, I have enjoyed feeding birds around my home. Hours have been spent with Peterson and Sibley close at hand and DeGraaf and Yamasaki’s New England Wildlife not far from reach. Friendships have been cemented while exchanging bird-feeding tips and squirrelavoidance techniques. I have become a more aware and engaged part of our beautiful world by watching the birds and their changes throughout the years.
My enjoyment was tinged with misgivings when I started working on hemlock woolly adelgid (HWA) issues for the Maine Forest Service. While this insect is just getting a foothold here in northern New England, I don’t have to travel far to see the damage it’s capable of. Hemlock forests in much of Massachusetts and Connecticut have been devastated, and the farther south you go, the worse the hemlocks fare. This loss ripples through the ecosystem and affects all kinds of plant and animal life, from shade-loving flora to brook trout.
When you work with forest pests every day, you become very aware of the role humans play in spreading exotic insects. I’ve become conscious of my behavior and concerned for my trees. To protect the privacy-giving hemlocks that line the perimeter of my lot in downtown Augusta, I won’t set foot in my backyard until I’ve showered and changed my clothes after returning from work in HWA-infested areas. I’ve spread the word about the hazards of moving firewood to anyone who would listen. I’ve dressed as an Asian longhorned beetle and paraded in front of thousands to raise awareness about invasive pests.
These things were easy. What was harder was accepting the fact that my birdfeeders were potentially part of the problem. Studies by entomologist Mark McClure, among others, indicate that birds are likely responsible for much of the long-distance and within community spread of HWA. It’s no coincidence that new outbreaks of the insect seem to be spreading up the Connecticut River Valley in Vermont and New Hampshire, as this area doubles as a migratory bird flyway. As an entomologist, I was forced to confront the fact that the birds flitting from my hemlocks, to the birdfeeder, then back to the hemlocks were putting the forest at risk. Begrudgingly, I took the feeders down, and now I only feed birds from November through March.
HWA is not the only reason to consider taking down your birdfeeders in the summer. Animals that visit birdfeeders can carry forest health threats including elongate hemlock scale, beech scale, and dwarf mistletoe. They also play a role in the spread of tree diseases such as chestnut blight and white pine blister rust, and it is thought that animals can spread dogwood anthracnose, butternut canker, and others. Although removing birdfeeders will not stop the spread of forest pests by birds and other feeder visitors, it may slow the spread of these pests into new areas and allow time for the development of new management techniques.
Other reasons to remove birdfeeders during the spring and summer are related to wildlife and human health. The Connecticut Agricultural Experiment Station’s Tick Management Handbook advises moving birdfeeders away from the house as one of its 14 actions that help control ticks. It also advises limiting feeder activity to the fall and winter, when subadult deer ticks aren’t around to feed on rodents and birds, the reservoir for the Lyme disease bacterium.
Tick-borne diseases are not the only disease concerns associated with birds in the summer. Birds may also be exposed to two mosquito-borne diseases, West Nile virus and eastern equine encephalitis. Recent studies of both diseases have shown that birds may be able to contaminate one another through pecking, and this pecking could be intensified by competition among birds at feeders. Other feeder visitors such as raccoons and bears create different kinds of risks for nearby wildlife, people, and pets.
I do not have the expertise to determine whether all summer bird feeding poses equal threats to forest, wildlife, and human health or whether the benefits to the birds, wildlife, and their watchers are outweighed by the risks. But I do know that by removing feeders, a landowner may forestall the degradation of critical forest habitat in the Northeast.
Like many other people who enjoy watching birds at their backyard feeders, I am dismayed at the thought of having to put mine away for the season. While I know this is the right thing to do, it doesn’t make it easy. This year the temptation to leave my feeders up was especially strong because my toddler would sit quietly watching the birds for half- hour stretches. But the risk of introducing invasive forest pests into my backyard, along with their potential to compromise an entire ecosystem, outweighs my personal wishes. If a lot of us put away our birdfeeders, it could make a real difference.
Allison Kanoti grew up in the woods of Vermont and New Hampshire and is today a forest entomologist with the Maine Forest Service. Allison gives permission to anyone interested in distributing this story.