Habitat
BREEDING: Inhabits a wide variety of wooded upland and lowland habitats including deciduous, coniferous, or mixed forests (Bond 1957, McCarty 1996). Occurs most frequently in forests with some degree of openness, whether it be the result of forest structure, natural disturbance, or human alteration (Palmer-Ball 1996). Intermediate-aged forests with a relatively sparse midstory are preferred (Crawford et al. 1981, Johnston and Odum 1956). Territories in such forests can be equally abundant under both an open or closed canopy (Johnston 1971). However, under some circumstances may be absent from closed-canopied forests (Hespenheide 1971). Tends to inhabit edges of younger forests having a relatively dense midstory (Palmer-Ball 1996, Strelke and Dickson 1980). Also occurs in anthropogenic habitats providing an open forested aspect such as parks and suburban neighborhoods (Palmer-Ball 1996). Nest is constructed atop a horizontal branch, 1.2-21.4 meters above the ground, in a wide variety of deciduous and coniferous trees (McCarty 1996, Terres 1991). NON-BREEDING: During migration through Central America, inhabits edges, clearings, and canopy of tall forest to second-growth scrub forest (Blake and Loiselle 1992, Greenberg 1992, Stiles and Skutch 1989). On wintering grounds inhabits secondary forest as well as edges or canopy gaps of primary forest (Fitzpatrick 1980, Pearson 1980, Stotz et al. 1992).
Ecology
Estimates of population density vary widely. Population density in Arkansas varies from 2-11 individuals/40.5 hectares [0.05-0.27 birds/ha] in uplands forests and from 2-13 individuals/40.5 hectares [0.04-0.32/ha] in bottomland forests, and territorial males are most abundant (25/40.5 hectares or 0.62/ha) in Ozark Mountain cedar glades (James and Neal 1986). Breeding pair density in Connecticut ranges from 0.4-1.7/10 hectares (0.04-0.17/ha; Askins and Philbrick 1987). In Illinois, breeding population density ranges from 1-67 birds/40.5 hectares (0.02-1.65/ha; Graber et al. 1974). In open, mixed pine-hardwood forest in Arkansas, density ranges from 5.2-14.9 birds/ha (Wilson et al. 1995). In Red Oak (QUERCUS RUBRA) forest in the Smoky Mountains, breeding pair density is 1.2/10 hectares (0.12/ha; Wilcove 1988). In three Illinois forest fragments, densities ranged from 0.32-0.86 pairs/ha during a 5-year period (Robinson 1992). In two studies conducted in Illinois, territory size averaged 0.76, 1.09, and 1.17 hectares (range 0.4-1.25) depending upon year of study. Territories were smaller in years of higher populations and larger with lower population densities (Graber et al. 1974). Exhibits breeding site fidelity. For example, 22.2% of individuals banded one year were recaptured the following year on the same net line in the same forest fragment in Illinois (Robinson 1992). Maximum life span is > 7 years (McCarty 1996).
Reproduction
Nesting dates (eggs or young) across the range vary from 6 May-1 September, with earliest nests occurring in the southern states and latest in the northern states and Canada. Later nests may represent renests or multiple broods, but data are lacking. Average clutch size is 3 eggs (range 2-4). Eggs are laid on consecutive days, but beginning of incubation in relation to oviposition is unknown. Incubation, by female only, requires 12-14 days. Young, who are fed by both parents, fledge in 16-18 days. Although multiple clutches/broods have not been documented, they are suspected to occur (McCarty 1996). Nest success (defined as a nest that fledged at least one young) was 100% in four nests studied in managed forests in Minnesota (Hanski et al. 1996) and 100% for seven nests examined in oak-hickory forest in Maryland (Chasko and Gates 1982). Thought to first breed at one year of age (J. McCarty, pers. comm.).