Kirtland’s warbler is a fairly large warbler is blue-gray above, yellow below, and heavily streaked with black on its back and sides. Its white eye-ring does not completely circle the eye and its wingbars are faint.
Songs and calls of the Kirtland’s Warbler
The Kirtland’s warbler is a loud and persistent singer on its breeding territory, though studies have shown that males sing during spring migration, from the Carolinas, northward. The song, which sounds like the chip-chip-che-way-o, is described as clear and not buzzy as many other warbler songs. The Kirtland’s warbler has a habit of wagging or bobbing its tail.
When and where to look:
This warbler, classified as an endangered species, nests only in a now strictly protected area in north-central Michigan. Its preferred habitat is in stands of young jack pines, where it nests on the ground. Kirtland’s warblers arrive in Michigan in early May and depart between August and October for their wintering grounds in the Bahamas.
These warblers forage on the ground and low in trees, where they glean or flycatch small insects such as sawflies, grasshoppers, and moths. Ripe fruits are also eaten, especially on the wintering grounds. Nestlings are fed a mix of insects and soft fruits.
Kirtland’s warblers form pairs about a week after arriving on the breeding grounds in mid-May. By the last week of May, weather permitting, egg laying begins. Eggs hatch in mid-June after a two-week incubation period. Young birds fledge after about nine days. Brown-headed cowbirds are a major threat to the nesting success of these warblers. A female cowbird can access and lay her egg in an unattended Kirtland’s nest and depart within 15 seconds. She may return later to remove warbler eggs to enhance the survival of her own offspring. Cowbird nestlings hatch earlier and are larger than warbler young, and so they are much more likely to survive in times of cold weather and food shortage. Efforts to control cowbirds have increased nesting success for Kirtland’s warbler.