A neotropical migrant, the Olive-sided Flycatcher starts to arrive in Western Washington by the first of May. It breeds in forests throughout the state. By mid-September it departs for its wintering grounds. It is easier to locate this migrant in spring when it is singing. Southbound migrants may be less vocal or silent. Keep an eye on dead snags or dead branches at the tops of live conifers for this flycatcher. It is one of the largest flycatchers, distinctive for its large bill and head, as well as for the dark flanks that form a vest to contrast with its light throat and belly.
As is the case with flycatchers, the Olive-sided Flycatcher eats a diet of insects. In summer it catches mostly wasps, winged ants and bees, including honey bees. It also eats grasshoppers, beetles, true bugs, and moths. Little is known about the specific insects it eats on its wintering grounds in South America. Its forages by catching insects in midair. It watches from a high, exposed perch, often from a dead branch at the top of a tree, sallies out to catch an insect, and then returns to its perch to eat.
The male defends its nesting territory by singing ceaselessly in spring, its song translated to “quick-three-beers.” Courtship behavior has not been studied but may involve active chasing through the forest canopy. The pair build the nest on a horizontal branch, well away from the trunk of the tree, and from 5 – 70 feet above ground. This flycatcher mostly nests in conifers but will sometimes nest in deciduous trees, which include tall eucalyptus trees in California’s coastal canyons. Generally, the Olive-sided Flycatcher prefers northern coniferous forests at higher elevations, seeking nest trees around the edges of open areas such as bogs, ponds, and clearings.
The female probably builds the nest, which is a shallow open cup of twigs, weeds, and grasses, lined with finer materials. The two to four eggs are incubated only by the female for about two weeks. Both adults feed the young, which take their first flight at about three weeks of age.
The oldest known Olive-sided Flycatcher was at least 11 years and 1 month of age when it was recaptured during a California banding operation. Flycatchers are not known to be social species, more often seen alone. Nonetheless, a number of collective nouns, which apply to any flycatcher species, have evolved to include outfield, swatting, zapper, and zipper.
The Olive-sided Flycatcher is on the State of the Birds Watch List because it is considered at risk of becoming threatened or endangered without conservation action. The population is now estimated at 1.7 million, having undergone a cumulative decline of 81 percent during the survey years 1966 to 2014. This is consistent with our local impression that the Olive-sided Flycatcher is more difficult to find in Edmonds during spring migration than it was 20 – 30 years ago. Reasons for the decline are poorly understood, with some speculation that there has been a loss of wintering habitat.
This is the song of the Olive-sided Flycatcher: https://www.xeno-canto.org/207797 .
The next Bird Lore column will be published Sept. 14.
— By Carol Riddell
Carol Riddell manages the bird education displays, on behalf of Pilchuck Audubon Society and Edmonds Parks & Recreation, at the Olympic Beach Visitor Station.