Contopus cooperi

A rather large (18-20 cm) flycatcher, large-headed, with a proportionately short tail. Plumage is brownish-olive above (browner on juveniles) with a dull white to yellowish throat, breast, and belly. The streaked or mottled chest patches are darker. Sexes are similar, but may be separable in the hand by wing chord length, 96-109 mm (females) and 103-117 mm (males) (Pyle et al. 1987).

The juvenal plumage, "...essentially like the adult in color pattern, but darker above and brighter below" (Bent 1942), is acquired by a complete postnatal molt. Banders recognize a combination juvenal/hatching year plumage from June to November with "upperparts dark brown; wing bars distinct, brownish-buffy or brownish-white; [and] flight feathers relatively fresh" (Pyle et al. 1987).

An after-hatching-year plumage between January and October consists of grayish-olive upperparts, indistinct, pale grayish-olive wing bars, and worn flight feathers. From April to August, breeding males have a cloacal protuberance, and breeding females have a brood patch (Pyle et al. 1987).

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 twigs and grasses, sometimes comprised of lichens of the genus USNEA, and lined with finer plant materials and hair.

VOCALIZATIONS: The song is a loud, ringing whistle, rather easily imitated, delivered by the male generally from the top of an upright dead snag or living tree (balsam fir (Abies balsamea), spruce (Picea spp.), tamarack (Larix laricina), or other pointed tree), often the tallest in the area. Most observers use the mnemonic "quick-three-beers" of (Peterson 1980) to recall the song. The song is often heard as a foreshortened "free beer." The call is a trebled "pip-pip-pip" (Peterson 1980). Oologist V. Burtch told Bent (1942) that these notes "...seemed to be made mostly by the female in the vicinity of the nest and that all the nests he found were located after hearing these notes."

Head (1903) described another vocalization as being "more like a twitter, and was uttered during excitement, chiefly when the young were learning to fly. It sounded like 'why, why, why,' repeated very rapidly a number of times. Sometimes this note was given as a prelude to the real song." Bent (1942) also describes a two-syllabled song, similar to the eastern wood-pewee's [Contopus sordidulus] in quality: "The notes may be whistled as `too-wee' in ascending pitch, slightly suggesting the [rufous-sided] towhee's [Pipilo erythrophthalmus] notes."

In the hand, can be separated from the wood-pewees (Contopus sordidulus and C. virens) by the longer (96-117 mm) wing, and from Greater Pewee (C. pertinax) by plumage, tail length (63-74 mm), and by the horn-colored to blackish lower mandible.

BRIEF SUMMARY: Olive-sided flycatchers breed in various forest and woodland habitats: taiga, subalpine coniferous forest, mixed coniferous-deciduous forest, burned-over forest, spruce or tamarack bogs and other forested wetlands, and along the forested edges of lakes, ponds, and streams Most nesting sites contain dead standing trees, which are used as singing and feeding perches. Nests are placed most often in conifers, on horizontal limbs 2-15 meters from the ground. During the northern winter, this species occurs in a variety of forest, woodland, and open situations with scattered trees, especially where tall dead snags are present.

BREEDING: in forest and woodland, especially in burned-over areas with standing dead trees, in taiga, subalpine coniferous forest and mixed coniferous-deciduous forest (AOU 1983). In Ontario, they nest in spruce or tamarack bogs, along the forested edges of beaver (Castor canadensis) ponds and rivers, and in burned-over forests (Cheskey 1987). In New York, however, where forest fires have been suppressed for much of this century, they favor small bog ponds and quaking bogs, swampy edges of lakes, marshy streams, backwaters of rivers, and beaver meadows. Most nesting sites contain dead standing trees, which are used as singing and feeding perches, and are bordered by forest (Peterson 1988). Birds also use small mountaintop ponds. Forests surrounding these sites are usually coniferous or mixed with deciduous trees. Black spruce (Picea mariana) is frequently mentioned as occurring at northern sites, and red spruce (P. rubens) at sites farther south, along with balsam fir, tamarack, and eastern hemlock (Tsuga canadensis) (Peterson 1988).

Forbush (1927) and Griscom and Snyder (1955) mentioned that in southern New England, pitch pine (Pinus rigida) habitats, including pine barrens, are preferred for nesting. Nesting occurs in swamps and open woods or small clearings where fire, flooding or timber harvesting have left standing dead trees (Forbush 1927). High elevation spruce-fir forests are used in the mountains of Virginia and North Carolina (Bailey 1913, Potter et al. 1980).

Nests are placed most often in conifers (Harrison 1978, 1979), on horizontal limbs from two to 15 m from the ground (Harrison 1979, Peck and James 1987). In Ontario, nests were found in black and white spruce (Picea glauca) (14 nests), jack pine (Pinus banksiana) (two nests), and balsam fir (one nest) (Peck and James 1987). Adirondack nests were built on an outer branch from 7.6-13.7 m high in balsam fir or spruce (Peterson 1988). Even though the nest is bulky, it is well concealed and rather difficult to find.

NON-BREEDING: Includes a variety of forest, woodland, and open situations with scattered trees, especially where tall dead snags are present (AOU 1983). Primary habitat is mature, evergreen montane forest (Altman 1997). Migrants in Costa Rica occur almost anywhere, in exposed snags and open branches; in winter mostly around edges and clearings, or broken canopy of highland forest and semi-open areas (Stiles and Skutch 1989).

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. This species apparently is a rare host to the brown-headed cowbird, with just three records of cowbird parasitism (Friedmann 1963, Terres 1980).

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).

Reported egg dates include the following (see Wright 199, Altman 1999): late May to early July in California; late May through late July in northwestern Oregon; early June to mid-July in western Washington; late May through mid-July in British Columbia; mid-June through mid-July in Colorado; early June through early July in Massachusetts; mid-June through late July in Maine; early to late June in Ontario and New York; mid-June through early July in Nova Scotia. In central Alaska, first clutches were initiated from late May through mid-June.

Clutch size is usually 3-4. Incubation, by the female, lasts 14-19 days. Young leave the nest 15-23 days after hatching. 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). Fledglings depend on parents for up to about a week after leaving the nest.

Renesting following loss of first clutch is common, second clutches may be smaller, three or even two eggs.