Breeding Bird Atlas 1 Species Accounts
Number of Broods
The Northern Waterthrushes that nest here arrive in late April and early May, but the species is a common migrant throughout the state, with the greatest passage occurring in mid-May. The male waterthrush sings readily in migration but is not always easy to see. As he walks along, teetering with tail bobbing among the tree roots on a muddy bank, he stays well within the shadowed protection of overhanging grasses or low branches. In a number of locales in Massachusetts, the breeding territories of the Northern Waterthrush overlap with those of the closely related Louisiana Waterthrush. The former species occupies the more sluggish portions of streams and adjacent swamps while the latter frequents the swift-flowing sections of brooks.
The name waterthrush is well deserved for this species resembles a thrush, and it feeds and nests on or near the ground in the immediate vicinity of water. In addition to swamps and sluggish streams, it frequents quiet or isolated ponds and lakes and even temporary pools of standing water such as rain-filled ditches. In such areas, these birds feed on insects—mosquitoes, flies, ants, etc.—and their larvae, slugs, and even tiny fish.
Several vocalizations of the Northern Waterthrush have been described. The familiar song, a loud, ringing, bubbling warble, emphatically delivered, may be heard until the middle of July. There is also a flight song that has been described as a longer, hurried, and jumbled version of the usual song with call notes interspersed. This is sung as the bird flies through or just above the woods. The common call or chip note is a sharp, thin, and metallic clink.
Nests have been found in or near moss-covered tree stumps, concealed in the broken roots of fallen trees or other debris, tucked away within a hollow of a muddy bank, or well hidden under an overhanging bank beneath grasses and low branches. They are always within close reach of water. The nesting bird utilizes the sphagnum moss growing in these damp areas as the primary material for nest construction. Apparently because the nest is so well hidden, the waterthrush is infrequently parasitized by cowbirds.
Astonishingly, a single nest studied in 1985 in New Jersey (Wander & Wander 1985) constitutes the only report in the literature on incubation and fledging age in this species. The nest contained a five-egg clutch, and the young hatched after 13 days of incubation (thought to have begun with the third egg laid). At 8 days of age, the five nestlings were banded and showed well-developed juvenal plumage, strongly resembling the adults in color (the young were whitish below) and pattern (the superciliary line distinctly showing). The young fledged 9 days after hatching.
There is very little specific information on the nesting of this species in Massachusetts. Two state nests each contained five eggs (DKW). Adults in Brookfield and West Brookfield were observed carrying food from June 15 to June 21, presumably for nestlings. A pair feeding four large fledglings was recorded on July 17 in Charlton (Meservey).
Waterthrushes begin their southward migration in July, with the peak occurring in late August to mid-September, but stragglers are found, especially along the coast, into early October and rarely to December. The winter range extends from Texas, Florida, and Bermuda through Central America and the West Indies south to Peru and Ecuador. Once in its winter quarters, a Northern Waterthrush quickly establishes a territory near water in which to lead a solitary existence.