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Species of Special Concern
Status
Alaska species of special concern; Federal species of management concern
Description
The olive-sided flycatcher is a stout, block-headed, short-tailed bird with a large bill. Its back is olive-gray-brown, with similar colored streaked sides. Dull white runs from the throat down the center of the breast to the light belly. Some characterize this underside as an “unbuttoned vest.” Pure white tufts are sometimes visible on perched birds poking from behind the wings above the rump, and also in front of the wings on the sides (this second set of tufts is not mentioned in most identification guides).
The birds commonly perch atop prominent snags or dead-topped spruce in spruce woods and bogs and chase dragonflies, wasps, and other large insect prey over the tree canopy or across muskegs and sloughs. In addition to their characteristic 3-note song, they may be identified by their loud “pip-pip-pip” or “pip-pip” call.
Habitats and Habits
The Olive-sided flycatcher is a long-distance (neotropical) migrant that belongs to the Tyrant Flycatcher family, one of many bird families originating in the hotbed of South America's rich and diverse environments.
Males return to central Alaska breeding areas in mid- to late May, with most females returning 1-2 weeks later. They remain in central Alaska through late August. Flycatchers feed from prominent perches by aerial hawking large insects, including bees, wasps, ants, and bark beetles. They nest almost exclusively on horizontal limbs of conifers, where they lay clutches of 4 eggs and raise one brood per season. Adults and young remain together for about two weeks after fledging. Very limited marking of adults indicates both breeding (by both sexes) and wintering site fidelity.
The olive-sided flycatcher is considered an indicator species of the coniferous forest biome throughout North America, although it is occasionally found in mixed deciduous/coniferous forests. This species is usually associated with openings, including muskegs, meadows, burns and logged areas; and water, including streams, beaver ponds, bogs and lakes. The olive-sided apparently requires uneven canopy or openings for aerial hawking, and wet areas productive of insect prey. These birds regularly use prominent dead or partially dead trees for perches for singing and hawking.
Causes of Decline
North American Breeding Bird Survey data provide strong evidence for population declines over most of the breeding range. Because no consistent impact is immediately obvious across its broad breeding range, initial concern has focussed on problems on the winter range. As noted above, its primary wintering habitat (based on limited anecdotal information)—mature evergreen forests of low-mid elevation in the Northern and Central Andes—is one of the most heavily altered habitats in South America. Andean valleys are almost completely deforested, and 85% or more of montane forests have been cut.
Potential impacts on the breeding range are less obvious. Fire suppression policies may have reduced breeding habitat by eliminating or reducing a primary mechanism for creating forest openings and uneven canopy structure. Logging would appear to create suitable habitat and singing males are detected using logged areas, but some speculate that logging is not equivalent to fire and that logged areas may not provide adequate prey or may expose olive-sideds to increased predation.
Range of the Olive-sided FlycatcherResearch and Recovery
Population monitoring continues using the North American Breeding Bird Survey; additional years of data are needed to determine trends in Alaska. Recent research found this standard survey to be adequate for tracking trends of this conspicuous songbird. Causes of declines, documented in many parts of contiguous U.S., are still poorly understood and require study. [Also see Preliminary Study of Olive-Sided Flycatchers. (PDF File 143K)]
Text: John Wright
For Additional Information
Please contact:
Doug Vincent-Lang
(907) 267-2339
