Around the Island

Mashomack Musings: Watching for warblers

This is a birder’s favorite time of year. It is the spring migration, with a variety of species returning from wintering in warmer climates.

Many birds migrate at night, dropping down into natural areas at dawn to rest and refuel. When the sun comes up, the birds begin to sing and call. Migratory birds are warming up for courtship, while year-round residents may have already started a brood.

Small, colorful warblers, sometimes dubbed the “butterflies of the forest” are passing through, with some staying locally to nest. At only 5 inches and weighing 1/3 of an ounce, they are active and vocal.

Warblers are fun to find. However, despite their bright colors, these birds can often be hard to see, flitting from branch to branch as they seek their insect prey. Listen first, then locate them by binoculars. Learning the songs so you can “bird by ear” is an immense advantage.

Many warblers are in decline. Habitat destruction, both on their wintering and breeding grounds, along with climate change, are the main stressors.

Migration is cued by length of day, a better predictor of time of year than temperature. However, plants and non-migratory critters respond to local temperatures. If trees bloom or leaf early, the accompanying insects also emerge early. If insectivorous warblers miss this critical window, they may go hungry, weakening their chance of survival.

You can help biologists track changes in bird populations by reporting observations to the New York State Breeding Bird Atlas (ebird.org/atlasny). For help identifying birds, try using the Merlin app by Cornell’s Lab of Ornithology (merlin.allaboutbirds.org).

The Blue-winged Warbler can be distinguished from other warblers by its heavy black bill and eye-line. (Credit: Derek Rodgers)