OLIVE-SIDED FLYCATCHER (Contopus cooperi)
Sallying forth from a perch atop a prominent snag to catch a bee or flying ant, the impressive foraging behavior of this species has earned it the name “peregrine of flycatchers” (Marshall 1988: 365). Its distinctive and far-reaching song, “quick-THREE-beers,” makes it an instantly recognizable denizen of montane forests, at least by ear. Olive-sided Flycatchers breed in conifer forests from Alaska to Labrador and Newfoundland south to n. New England, New York, and the Great Lakes states in the east and along the major mountain ranges of the west to s. California, Arizona, and New Mexico. Isolated breeding populations occur in Baja California Norte, w. Texas, Massachusetts, Connecticut, West Virginia, North Carolina, and Tennessee. The main winter range is from Panama to n. and w. South America, with the highest abundance in the Colombian Andes; smaller numbers winter in s. Mexico, Guatemala, Belize, and Costa Rica (Altman and Sallabanks 2000).
Subspecies: C. c. cooperi
Status and Occurrence: Uncommon breeding resident in w. third of state, and probable breeder in the Judith, Belt, Highwood, and Pryor Mts. east of the Continental Divide; uncommon migrant elsewhere. Arrives from late May to early Jun; earliest sighting 12 May 1994 in Lewis and Clark Co. by Rob Fergus. On the basis of 18 nests found by Ty Smucker in Missoula and Powell Cos., nest building and egg laying occur in the last half of Jun, and fledging occurs from late Jul to early Aug. Fall migration occurs from mid-Aug to early Sep; latest sighting 15 Sep 2003 in Gallatin Co. by Robin Wolcott.
F. H. Knowlton collected one on Trail Creek between Bozeman and Livingston on 28 Jul 1890 (Richmond and Knowlton 1894), but its whereabouts are unknown. The earliest extant specimen was taken by A. H. Howell at Saint Mary Lake on 24 May 1895 (USNM 140021). Other early specimens from the breeding range were obtained at Flathead Lake on 7 Aug 1900 (UMZM 1949) and on Mount MacDougal on 10 Aug 1901 (UMZM 2031). C. F. Hedges collected five migrants from the Miles City area, one in Jun 1902 (UMZM 2030) and four in Aug from 1919 to 1921 (FMNH 140524, 140525, 173584, 173585).
Habitat: Olive-sided Flycatchers inhabit forest openings, forest edges near openings, and open or semi-open forest stands with low canopy closure (Altman 1997). They are more common in early postfire habitats than in any other major cover type, although they also use harvested live stands with structure that mimics postfire habitat, particularly those with high densities of snags (Hutto and Young 1999). In w. Montana, they are more abundant in logged (i.e., clearcut and partial cut) than in unlogged forests (Tobalske et al. 1991).
Range-wide, they occur regularly but in low densities in forests dominated by spruce and aspen; uncommonly in mixed conifers, ponderosa pine, and cedar-hemlock; and rarely in lodgepole pine and pinyon-juniper (Hejl et al. 1995, Hutto 1995). Although they are more common in early successional forest types, they require large snags and/or large live trees for foraging and singing perches (Altman 1997). Typical nests are open cups placed toward the end of a horizontal branch of a conifer, high above the ground. Of 36 nests found in nw. Montana in 2002, most were in subalpine fir (66%) or Engelman spruce (28%) in a harvested site, and 94% were in dead subalpine firs with remnant needles in a burned site; nest height averaged 12.1 m above ground (Robertson and Hutto 2007).
Conservation: Level I Priority and Species of Concern in Montana. Also listed as Near Threatened by BirdLife International. BBS data indicate a significant decline in numbers of 3.3% per year survey-wide from 1980 to 2007. Data for Montana are derived from inadequate sample sizes and suggest a nonsignificant decline of 0.2% per year during the same period. The global population estimate is 1.2 million birds (Rich et al. 2004).
Initial speculation on causes of declines in the U.S. and Canada focused on habitat alteration on the wintering grounds (Altman 1997). The species is considered to be among the most highly vulnerable of the Nearctic-Neotropical migratory landbirds to habitat destruction in the tropics (Petit et al. 1993, 1995). Research in Montana indicates that this species uses managed forest types that have similar structural conditions to postfire habitat but may function as population sinks, further contributing to declines (Hutto 1995, Robertson and Hutto 2007; see Contemporary Work below).
Management recommendations include leaving large trees and snags, especially those that are higher than the average canopy height of the stand that was harvested; maintaining stands with relatively open canopy cover; and allowing fires to burn at high severity in some areas (Casey 2000, Smucker et al. 2005).
Historical Notes: Mention of Olive-sided Flycatchers is notably absent in the writings of Hayden, Cooper, Allen, Coues, and Grinnell, suggesting that these naturalists did not encounter the species in Montana. Indeed, the earliest reference from presumed breeding habitat is by Williams (1882: 62), whose sole remark from observations in the Big Belt Mts. in the summer of 1880 was “One bird seen.” Similarly, Richmond and Knowlton (1894: 304), who traveled extensively in suitable habitat in the Bozeman area, said only “One shot on Traill Creek, July 28.” A statement about the species’ distribution made nearly a century ago is equally appropriate today: “A summer resident of the mountains in the western half of the state. Not common but widely distributed” (Saunders 1921: 86). Saunders further stated that “While the bird is not common, the loud whistle of the male, coming from his perch in the dead top of a fir, carries for a long distance and proclaims his presence.” This flycatcher’s penchant for prominent perches also was noted by Silloway (1901: 55), who commented that “A specimen was sitting in the bare top of a tall tree, uttering its harsh, querulous call."
Contemporary Work: The Landbird Monitoring Program at the University of Montana’s Avian Science Center has contributed hundreds of breeding-season records that have generated a wealth of information on habitat affinities of this species (Hutto and Young 1999). Two studies that grew out of the monitoring program have been especially enlightening with regard to conservation. In comparing data from points sampled before and after wildfires in the Bitterroot NF, Smucker et al. (2005) observed that numbers increased significantly in forest stands that burned at high severity. Their results highlight the need to consider fire severity in studies of fire effects on birds and underscore the importance of managing public forest lands for the maintenance of all types of fires. Robertson and Hutto (2007) found that Olive-sided Flycatchers readily nest in naturally burned forest and in selectively harvested forest in w. Montana. Nesting density and nestling feeding rates actually were higher in harvested forest than in burned forest, but nesting success was much lower in the former habitat. They attributed the reduced nesting success to a higher number of nest predators in harvested forest, which acts like an “ecological trap” because it attracts the flycatchers to a human-created habitat that resembles the structure of their preferred natural habitat. The influence of this phenomenon on the long-term status of the species remains to be determined.
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