Breeding Bird Atlas 1 Species Accounts
Number of Broods
The current state breeding range of the Magnolia Warbler almost exactly matches that occupied in the 1920s, but Forbush also showed a few widely scattered breeding season records for Middlesex, Essex, and Plymouth counties. Historically, the species may have been more widely distributed in Massachusetts, hanging on for a time in a few isolated eastern pockets, but some combination of factors has since led to the disappearance of these outposts.
During the first week of May, breeding birds begin to appear, and by the middle of the month the species becomes common as later arrivals show up along with many northbound migrants. By late May, the migrant wave has passed, but a few stragglers are observed into the first week of June. Resident males claim and defend breeding territories, which are occasionally in deep coniferous forest but are more commonly in more open areas in one of two types of situations. The first is a forest clearing where young spruces and hemlocks can be found in addition to more mature trees; the second is an abandoned field or pasture grown up to Red Cedars, pines, and Pasture-junipers. In certain favorable locales, several territories may abut one another. It is difficult to understand why some areas support breeding populations of this species while nearby zones of apparently suitable habitat are not occupied.
As is the case with many warbler species, unmated male Magnolia Warblers often sing repeatedly for long periods of time, and once a female arrives it may be pursued or followed about the territory. Songs are variable but can be divided into two main types. The more familiar pattern can be represented as wee-o, wee-o, wee-chy or wichy, wichy, wee-see, and the alternate as weetee, weet, wur, with a low ending note. Calls include a loud chip note, a characteristic softer tlep note, a scolding tit-tit-tit, and a unique and surprisingly jaylike de kay, kay, kay, uttered when the birds are agitated. The young have a begging call consisting of a long series of two- or three-note phrases: tsee-tsee, tsee, tsee, tu, etc.
Nests are almost always situated in a conifer, from 1 to 35 feet high but more commonly not above 6 feet, and may be positioned either at the top of a small tree or out from the trunk on a horizontal branch. A nest in Pelham, believed to be a second attempt following failure, was constructed from June 17 to June 21 in a clump of juniper. It was 33 inches from the ground and well hidden from view (Nice 1926). While there are reports of males helping to gather materials for building the nest, the actual work of construction is done by the female. Pieces of dry grass, spruce, twigs, pine needles, and spiderwebs may be used for the outside of the structure, which is lined with hair, moss, or fine rootlets, especially black ones. The Pelham nest was typical, being composed of dried grass stems with a lining of pine needles and black horsehair (Nice 1926).
The most common clutch size is four, with the range being three to six eggs. A Worcester County nest contained four eggs on June 15 (DKW), and at a Pelham nest three eggs were laid on June 22, 23, and 24, respectively (Nice 1926). At a second Pelham nest, laying was estimated to have occurred between July 15 and 18 (Nice 1928). Incubation lasts from 11 to 13 days and is generally carried out by the female, although there are records of males remaining on nests for brief periods. For the 8 to 10 days that the young remain in the nest, they are fed by both parents. At hatching the tiny young are helpless and require brooding by the female. Their eyes open on day 3 or 4, they begin to show feathering and become more active on day 6, and they are well feathered by day 8 or 9. Nestlings have been reported in Massachusetts from July 6 to August 7. The July 6 date was a known hatch day, the young fledging on July 16. July 29 to 30 was an estimated hatch period for another state nest (Nice 1926, 1928).
Parental care continues for several weeks as the fledglings gradually become self-sufficient. At this time, the family groups may wander away from the breeding territory. In Massachusetts, adults have been observed feeding fledglings from July 14 to August 20 (Nice 1926, 1928). Two second-brood young, recently fledged on August 9, were still being fed on August 20 (Nice 1928). Some Magnolia Warbler pairs rear two broods, and in these cases the male cares for the first-brood young while the female builds a new nest and produces a second clutch in July. Because some pairs are well established on territory by mid-May, it is likely that there are earlier dates for both eggs and young than have been reported.
Adults undergo a complete molt in July or August, once they have finished their breeding duties. Both young and old birds join mixed flocks of Black-capped Chickadees, warblers, and other species and forage in these groups throughout August. By the first week of September, most of the resident birds have departed on their southward flight. Migrants from farther north continue to pass throughout the month, with small numbers being regularly encountered into the third week of October. After this date, only a few stragglers are observed. Winter quarters are in Mexico, Central America, and the West Indies.