There are a lot of things I look forward to in fall, especially because I live and work at Goose Pond Sanctuary. I welcome the wooly bears marching en masse, goose tornadoes over the pond, heaps of ripening seeds, and of course, the flow of migrating birds. However, the hoards of flies accumulating in my windows is something I could live without. In fall and spring, cleaning up flies becomes a not-too-exciting part of my daily routine. That is, until I started noticing quick streaks flashing by my windows.
Multiple days passed before I realized that the flit out of the corner of my eyes happened way too consistently to be my imagination, so I started paying closer attention. Finally, I watched long enough for the streak to come to a stop on my windowsill—the culprit had white ‘eyebrows,’ light brown streaks across a white belly, and a hint of yellow under its tail. My mind was not playing tricks on me, but the Palm Warblers in fall plumage might have been. It turns out that Palm Warblers’ primary diet is composed of insects like flies, caterpillars, and beetles, and that they were ‘sallying out’ or ‘hawking’ the flies in the windows. These terms refer to birds’ insect-hunting technique, often utilized by flycatchers, where they launch from a perch, catch an insect midflight, and return to their perch in preparation to do it again.
Palm Warbler in fall plumage perched on a branch (photo by Arlene Koziol).
Like most birds, window collisions are a threat to Palm Warblers. If you notice that birds are hitting your windows at home, it’s critical to monitor and identify which windows are problems. Once you do, there are many ways to make the glass more visible: you can put up insect screens, apply dot decals, or hang paracord curtains outside so that birds see they’re approaching a hard surface. We use a few of those techniques at the two Goose Pond residences and have noticed a reduction in window collisions.
Cornell Lab’s All About Birds describes the Palm Warbler as a “warbler that doesn’t act like one.” For one, Palm Warblers spend considerably more time walking on the ground than other warblers, and are often seen foraging with sparrows and juncos. A few years ago in mid-October, Mark Martin and Steve Thiessen were searching for sparrows in a few weedy areas around Goose Pond and counted 17 Palm Warblers in the mix, the only warbler species of the day. Their tail wagging, or bobbing, is another trait that separates them, and is apparent whether they are on the ground or perched in a tree or shrub. I will always value scientific research, but there is a certain charm to peoples’ personal observations and decisions about the natural world. I especially appreciate a bunch of bird experts, heads together, determining that this warbler just doesn’t act like one. And I have to agree—the wagging tail, curious eyes, and tilted head of the Palm Warbler on my windowsill seemed more to me like a dog than a warbler.
Palm Warbler range map (courtesy of Birds of the World).
Palm Warblers are one of the most abundant warbler species at Goose Pond during fall migration. I’ve been enjoying my time watching them by my windows, hopping in shrubs, and rummaging around in weedy fields and food plots, but their time here (and much of Wisconsin, in general) is a small snippet of their lives and migratory journey. Although a few Palm Warblers nest in northern Wisconsin, 98% of them breed in Canada’s expansive boreal forest, also referred to as North America’s bird nursery. This makes them one of the northernmost breeding warblers, only beaten out by the Blackpoll Warbler who nests in northern Canada and into Alaska. Come winter, Palm Warblers will be enjoying the open savannas and prairies, coastal scrub, marshes, young woods, weedy fields, and forest edges of the southeastern coast of the United States, the Caribbean islands, and east coast of Central America.
Until then, I will admire their playful spirit as they chase the flies stirred up by my vacuum and look at me, head tilted, saying ‘let’s go again!’ after I finish. But don’t worry, there are enough flies outside the windows, waiting to find their way in, that the Palm Warblers won’t leave hungry!
Written by Emma Raasch, Goose Pond Sanctuary ecological restoration technician
Cover image by Andy Reago & Chrissy McClarren. A Palm Warbler (in breeding plumage) walks along the ground in a wooded area.
