In a state the size of Maine, the bird nesting season is somewhat protracted, due to distances across regions and to the calendar timings of each given species. Locally, we see a continuum of birds engaged in various stages of actions. Take wild turkeys, for example. By now, many hen turkeys have half-grown, fully feathered chicks, foraging with the adults. The more recent clutches contain smaller individuals, still in juvenile phases of development. While pursuing the Maine Bird Atlas project last week, I approached a cavernous, commercial sand pit, where a hen turkey guided a contingent of three juveniles. This was an awkward, and potentially hazardous, situation for the turkeys, since they were midway across a wide-open expanse, affording few opportunities to hide from danger. After ducking behind a clump of weeds, the adult clucked and ran, trying to divert me from her chicks. The silent poults stayed put, obscured by the sparse patch of weeds.

As I skirted around the turkey family, a distinctive warbler song reached my ear: an ascending, buzzy zoo-zoo, zoo, ZEEEEET that steadily climbed in pitch. It was a colorful male prairie warbler, a slightly unusual species for these parts during the nesting season. This warbler’s common name has little connection with traditional prairie grass habitats that might come to mind. Instead, its prairie name was derived from low, grassy openings occurring in pine woods of Florida, where the species is a year-round resident.

This warbler’s range has expanded northward in recent times, now nesting in limited numbers in parts of south-central and interior midcoastal Maine. With its olive-green back, bright yellow under parts, and bold black stripes on face, sides and flanks, this warbler is eye-catching. The sand pit male sang persistently from several perches, but I saw no evidence of nesting activity. Atlasing designations for confirmed breeding status can include: a nest containing eggs or young, newly fledged young, an adult carrying food or fecal sacs, an occupied nest, carrying nesting materials or building a nest.

Prairie warbler nests are typically constructed in densely overgrown fields, young second-growth scrub or brushy areas, and areas affected by forest clearing or fires. The sand pit’s perimeters made a perfect setting, as well. Long-term nest locations may shift, as these temporary habitats revert to mature forest. Nest parasitism by brown-headed cowbirds is another concern. Cowbird predations are more likely in areas of fragmented forest, where it is easier for cowbirds to locate nests of other birds.

A day earlier, I’d happened upon a begging cowbird chick that was being fed by a pair of chestnut-sided warblers, common victims of cowbirds. The juvenile cowbird’s two-syllable peeps intensified whenever the fostering parents approached to deliver food. There was a second, and happier, surprise to witness, however: a chestnut-sided warbler fledgling was also receiving his parents’ food provisions.

Female brown-headed cowbirds lay an average of forty eggs per year in the nests of other birds. Of these, an estimated two or three hatchlings mature to adulthood. Nest-searching occurs primarily in the mornings and is conducted by the female alone. Females may perch in a high vantage point of a tree and observe the activity of surrounding birds. Other tactics involve finding active nest building by potential host species.

Responses to cowbird eggs vary somewhat by host species. Certain species, such as robins and catbirds, tend to recognize the egg as foreign, puncture it, and remove it. Other birds, such as yellow warblers and phoebes, may desert the nest or build a new nest on top of it. The remaining species accept the egg and incubate it as their own.