Breeding Bird Atlas 1 Species Accounts
Number of Broods
A population decline of the Golden-winged Warbler throughout much of its range has been well documented, and the major reasons for that decline are twofold. First, for much of the nineteenth century, the Massachusetts landscape was approximately 85 percent cleared of forests for agricultural and logging purposes. Subsequent changing land use patterns allowed abandoned pasture to grow into second-growth woodlands, ideal habitat for Golden-winged Warblers. Over time, these woodlands matured into hardwood (primarily oak) forests that were unsuitable for Golden-winged Warblers. Second, since the late 1950s, the population of the closely related Blue-winged Warbler has increased dramatically and spread into what little Golden-winged Warbler habitat remained (see Blue-winged Warbler account). In addition to the well-known hybridization of the two species, the Blue-winged Warbler is behaviorally more aggressive and eventually replaces the Golden-winged Warbler.
The situation in Worcester County illustrates this pattern of replacement. Prior to the late 1930s, the Golden-winged Warbler was a regular, but uncommon, nester throughout the county. The first Blue-winged Warbler was reported in 1938, and by the early 1960s the species had established itself as a common breeder. “Brewster’s” hybrids have been reported from 1943 onward, and the rarer “Lawrence’s” hybrid (which indicates an advanced state of contact between the two parent species) has been reported from 1968 to the present. By the late 1970s, reports of successful nesting of the Golden-winged Warbler practically ceased, and most reports were of unmated males, with a high proportion giving Blue-winged Warbler type songs and aberrant songs. During the Atlas period, the Golden-winged Warbler was rare and declining. Since the close of the Atlas period, there have been a few records of migrants and lone territorial males.
In eastern Massachusetts, the decline in Golden-winged Warblers since the late 1950s has been equally serious. As an example, there were approximately 25 pairs (based on singing males) in Wellesley in 1954, where none could be found by 1980. The last strongholds for them were in northern Essex County from North Andover to West Newbury, with another population pocket persisting in the Franklin-Medfield area, but both of these have since been replaced by Blue-winged Warblers and hybrids.
Although the Golden-winged Warbler was not confirmed breeding in Berkshire County during the Atlas period, the number of probable reports indicated that nesting was occurring. In western Massachusetts, in alarmingly low numbers, the Golden-winged Warbler is making its last stand. In recent years, there has been a cluster of reports from the Housatonic River valley. The outlook for the ultimate survival of this species in the state is gloomy, and the bird is listed as endangered by the Massachusetts Division of Fisheries and Wildlife.
The favored habitat of the Golden-winged Warbler is second-growth woodlands, especially on hillsides, where Gray Birch and associated shrubby vegetation predominate. Other suitable nesting areas are damp meadows overgrown with weeds and saplings, power-line cuts, and abandoned orchards. Male Golden-winged Warblers arrive on the breeding grounds during the first week of May. They immediately set up territories, which include the brushy areas nearby and their forest edge, and announce their presence by singing their distinctive buzzy song. The song is frequently given from an exposed dead branch of a tree at the edge of the woodland. Typical songs consist of three or four notes, the introductory note higher than the succeeding ones, which are all on the same pitch: zeee zer-zer-zer or zee-ze-ze. Songs of a second type are used in different contexts and are longer and more rapid: see-see-see-see-see-see-see-see-see-dz-dsee. Call notes are similar, if not identical, to those of the Blue-winged Warbler.
Females arrive about 10 days after the males. During courtship, the male may posture, present food, or follow and chase the female. Nests, constructed by the female, are usually located near the edge of a field or pasture with trees that provide shade for most of the day and are built on or slightly above the ground in herbaceous clumps. In a series of nests from eastern Massachusetts, the most common site was in a cluster of goldenrod, the nests becoming more concealed as the weeds grew. Other nests were found at the bases of briers and small saplings, in tussocks of meadow grass, and in clumps of low weeds such as ironweed (ACB). The nest itself is a bulky structure, usually set on a base of dead leaves and constructed of dry leaves with a coarse lining of bark and grasses. The clutches averaged four eggs, rarely five or six eggs; there was one record of seven eggs (ACB). Once the female begins incubation, which takes 10 days, the male becomes less vocal and uses the longer songs more often.
Both sexes feed the young, which fledge in about 10 days. Nestlings have been reported in the state from June 9 to June 16 and fledglings from June 23 to August 4 (TC, BOEM). The actual range of dates is potentially greater and probably cor-responds to those of the Blue-winged Warbler. One brood is raised each season, and there is no information on renesting. The adults undergo a complete molt after nesting, and the young acquire their first winter plumage about a month after fledging. Until they depart in late August and early September, Golden-winged Warblers join mixed-species flocks. The wintering grounds are from Central America to northern South America.