Habitat
BREEDING: Inhabits young, medium-aged and mature deciduous and mixed forests (Bushman and Therres 1988, Kricher 1995). Studies of habitat selection have yielded conflicting results which appear to be due to geography, as well as variations in forest type and stand age. In the southern part of its range, this species appears to be most closely associated with relatively closed-canopied forests having low shrub density (Conner et al. 1983, Crawford et al. 1981, Noon et al. 1980, Wilson et al. 1995). In Maine and Michigan, it occupies relatively open forests having high shrub density (Noon et al. 1980). Associated with intermediate canopy closure and dense understory vegetation in American Beech-Yellow Birch-Sugar Maple forests in Vermont (Thompson and Capen 1988). More abundant in mature than successional aspen and oak stands in managed forests of Pennsylvania, where its presence correlates with density of understory trees and tall shrubs (Yahner 1986).
In aspen forests of Alberta, however, stands with high shrub density were avoided (Westworth and Telfer 1993). Associated with high tree density and high canopy volume (indicative of mid- to late-successional forests) in mixed forests of central Ontario (Clark et al. 1983). In Red Maple (ACER RUBRUM)-Sugar Maple-Paper Birch (BETULA PAPYRIFERA)-Yellow Birch forests in Nova Scotia, closed-canopied stands having low shrub density were preferred over open-canopied stands with high shrub density (Freedman et al. 1981). In Northern Red Oak (QUERCUS RUBRA)-Red Maple forest in Massachusetts, relatively open canopied stands with moderate shrub densities were preferred (Chadwick et al. 1986). Typically nests on the ground, often adjacent to a tree, shrub, rock, stump or log, under a shrub or dead branches, or, more rarely, atop stumps (Bent 1953, Kricher 1995).
NON-BREEDING: Uses a wide variety of habitats during the winter, from early successional disturbed areas to mature forests (Kricher 1995). Caribbean habitats utilized include coastal forest, dry interior forest, wet forest, forest edge, pine woods, riparian areas, wetlands, urban habitats that provide plant cover, and some open areas (Arendt 1992). Also inhabits cacao, citrus, mango, shade coffee, and pine plantations in Puerto Rico, Jamaica, and Costa Rica (Robbins et al. 1992). In Costa Rica, inhabits both young, second-growth forest and primary forest, as well as parks and gardens having large trees (Blake and Loiselle 1992, Stiles and Skutch 1989). Considered a habitat generalist in western Mexico, even though it showed a preference for undisturbed habitats, particularly forest (Hutto 1992). Prefers primary forest over other habitat types in the Yucatan Peninsula, Mexico (Greenberg 1992, Lynch 1989) and in Veracruz, Mexico (Rappole et al. 1992). In the Virgin Islands, exhibited a preference for moist forest (90.5% of detections) over other habitat types (Askins et al. 1992).
Ecology
DENSITY/TERRITORIALITY: Density of breeding birds is low in Illinois, averaging 0.1 individuals/40.5 hectares (Graber et al. 1983). Density of territorial males in the Ozark Mountains of Arkansas ranges from 6-29/40.5 hectares depending upon forest type (James and Neal 1986). Breeding pair density in various forest types in the southern Appalachian Mountains varied from 1.2-4.2/10 hectares (Wilcove 1988). In the Missouri Ozarks, territory density ranged from 0.47-3.24/10 hectares depending upon forest stand age (Thompson et al. 1992). Breeding territories in aspen forest in Alberta range from 14-28.7/100 hectares (Westworth and Telfer 1993). In Nova Scotia, density of breeding pairs ranged from 15-50/km2 in uncut forest and from 15-70/km2 in strip-cut forest (Freedman et al. 1981). Density of individuals ranged from 0.9-2.3/10 hectares in Pennsylvania (Yahner 1993). In trembling aspen (POPULUS TREMULOIDES) forest in Alberta, male pairing success was lower in forest fragments (56%) than in continuous forest (80%) but, due to small sample sizes, the difference was not statistically significant (Sodhi and Paszkowski 1997). In winter in the Virgin Islands, occurs commonly in small mixed species flocks of warblers; density in moist forest was less than 1/ha on St. Thomas and 1-2/ha on St. John (Ewert and Askins 1991). Conflicting reports of winter territoriality (Faaborg and Arendt 1984, Morton 1980).
SITE FIDELITY: Exhibits site fidelity: on the wintering grounds in Puerto Rico, 22% of banded birds were recaptured at the study site. The average time between banding and recapture was 1.9 years, the longest interval was 4 years (Faaborg and Arendt 1984). Twenty percent of birds captured in Cuba were birds banded there the previous year (Gonzalez-Alonso et al. 1992).
POPULATION PARAMETERS: Average annual adult survivorship is estimated to be 71%, and the oldest known individual lived to be 11 years, 3 months old (Klimkiewicz et al. 1983, Kricher 1995).
PARASITES: Parasitized by blood parasites (HAEMOPROTEUS spp. and LEUCOCYTOZOON spp.), feather mites, a louse (MYRSIDEA INCERTA), and a fly (ORNITHOICA CONFLUENS) (Bent 1953, Kricher 1995). Maggots destroyed a nestful of young (Bent 1953).
Reproduction
Breeding begins as early as mid-April at southern latitudes and as late as late July at northern latitudes. Clutch size is usually five, and ranges from 4-6 eggs. Eggs are laid daily until the clutch is complete. Incubation, which requires 10-12 days, begins when the penultimate or last egg is laid and is by the female only. The young are fed by both parents and leave the nest at 8-12 days posthatching. Single brooded, though double broods are suspected (Kricher 1995). In Arkansas, 73.7% of 19 nests were successful (fledged at least one young; Martin 1993). Age at sexual maturity is unknown (Kricher 1995).