| General Species Description: |
Reproduction Comments:Courtship includes territorial fights between males, and males pursuing females across the canopies of coniferous forests. Courtship continues for at least two weeks until nest sites are chosen and pairing is completed (Bent 1942). Clutches normally of three (rarely four) (Harrison 1978, Altman and Sallabanks 2000); four in Central Alaska (n=10 first clutches; Wright 1997); 62% three eggs, 32% four eggs in Oregon (n=50 clutches; Altman 1999). Egg dates are 6-24 June in Ontario (Peck and James 1987), 9-27 June in New York,14 June in Vermont (Fichtel 1985), 27 May to 29 July (n=154, Altman 1999), and 31 May-16 June for first eggs of 12 first clutches in central Alaska (Wright 1997). Renesting following loss of first clutch is common, second clutches may be smaller, three or even two eggs. The incubation period is 14-17 days in New York, 15-16 in Oregon (Altman 1999), 15-16 in Alaska with mean hatch date of 28 June (Wright 1997). Incubation is by the female. Nestlings leave the nest at 15-19 days (Harrison 1978). Most fledging occurs in early to mid July, though young from renesting efforts may fledge late in July. In New York State records of unfledged juveniles on 22 June and fledglings from 10-24 July, and in Oregon most young fledged in 19-21 days (Altman 1999). In Alaska fledging recorded at 19-20 days after hatching of first egg for 2 nests (Wright 1997). Singing behavior relative to nesting period is detailed in Wright 1997.
Eggs: creamy white, buff, or pink, and lightly wreathed on the broad end with brown or gray blotches (Harrison 1978).
Nest: a loosely formed cup of dead twigs, sticks and rootlets, often lined with arboreal lichens such as Usnea; constructed on branch of coniferous tree.
Ecology Comments:Considered an indicator species of the coniferous forest biome throughout North America, although occasionally found in mixed deciduous/coniferous forests. Usually territorial in non-breeding areas (Stiles and Skutch 1989) and may display strong year-to-year site fidelity on breeding (Wright 1997) and wintering grounds (Marshall 1988, Altman 1997). In a study of 16 insectivorous, aerially-foraging neotropical flycatcher species, including the olive-sided flycatcher, that are seasonally sympatric in the humid Caribbean lowlands of Costa Rica, Sherry (1984) found that migrants are more opportunistic while wintering than the syntopic year-round residents.
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