This October, every time I go into a forest I seem to find yellow-rumped warblers — whether at my window in Hampden, on the Orono Bog Boardwalk, at Dorothea Dix Park or at Essex Woods in Bangor.
This warbler is the most common warbler in Maine. They are the first to arrive in the spring and the last warblers to leave in fall. At this time of year you may see yellow-rumped warblers migrating south, often in groups.
In May and June, they build nests on spruce, pine and cedar trees, usually on a horizontal branch about 15 feet high, close to the trunk. They use conifer twigs and rootlets, which keep the nest together. Next they line the inside of the nest with soft hairs, such as moose hair and small feathers, to keep their young warm.
In Maine, these warblers feed their young many species of beetles, aphids, flies, mosquitoes and spiders. They glean insects from conifer trees in summer.
As fall comes and migration begins, yellow-rumped warblers start to eat berries, especially wax-myrtle berries and bay berries. These berries have oil inside and offer many of the calories in the yellow-rumped warbler’s diet.
I’m also seeing them in deciduous trees, especially oaks. Here they use two different strategies to catch insects. They forage for crawling insects and spiders on oak leaves and twigs, but they also will fly out from the branch and snap up airborne insects, the way flycatchers do.
When yellow-rumped warblers migrate, some go to the southern United States and Central America, from Mexico to Panama. A few stay in southern Maine and New England.
For information on Fields Pond Audubon Center, call 989-2591.