Bird of the Month: Hermit Warbler
By Andy McCormick
Hermit Warbler
Scientific Name: Setophaga occidentalis
Length: 5 inches
Wingspan: 8 inches
Weight: 0.32 oz
AOU Code: HEWA
The Hermit Warbler is considered a specialist in living in the canopy of 200 foot tall conifers. In western Washington it populates Douglas firs, western hemlocks, and western red cedars. It winters in pine-oak forests in Mexico and in California it enjoys Jeffrey, pondersosa, and lodgepole pines. It forages so high that it is often heard long before it is seen.
High Wire Specialist
The Hermit is not really solitary. It is just difficult to find high in the canopy. It begins foraging near the trunk and works its way toward the end of a branch, and then flies into a trunk to start on another branch, but not always in the same tree. It uses a variety of techniques employed by other canopy birds. It sometimes hover-gleans as Golden-crowned Kinglets do, as they pick insects from leaves and twigs while staying steady in flight. It will also hang onto branches as chickadees do. Using a third method similar to flycatchers, but less often than other means, it will sally out to hawk insects in the air. The Hermit Warbler’s diet consists almost entirely of insects.
The Hermit Warbler migrates strictly along the Pacific Flyway. It is an early migrant arriving on the breeding grounds in early May. In the fall it leaves the breeding area earlier than other warblers, typically heading south in early August or even late July. It follows the forests until some birds settle in California and others winter in the forests of western Mexico.
Warbler Sisters
The Hermit Warbler is a sister species of Townsend’s Warbler (S. townsendi) and both are part of the virens superspecies which also includes the Black-throated Gray, Golden-cheeked, and Black-throated Green Warblers (Dunn and Garrett). The Hermit and Townsend’s Warblers enjoy similar habitat and hybridize regularly in areas where they overlap in Southwest Washington and on the east side of the Olympic Peninsula. Recent studies find that the range of the hybridization zone is moving south, which may indicate that Townsend’s Warbler is competitively superior to the Hermit Warbler (Pearson). Hybrids will generally keep the yellow face of the Hermit Warbler, and show yellow on the breast similar to Townsend’s Warbler.
The Hermit is in the genus Setophaga, moth eater, from the Greek setos, moth, and phagein, eat, with the species name occidentalis, of the west, based on its habitat in western Washington, Oregon, and California. Difficulty in finding this bird led to the name Hermit. However, this species is not solitary in its habits (Holloway), and it will be found in mixed flocks in the early spring.
Made in Washington
The Hermit Warbler breeds in Pacific Northwest coniferous forests. The female builds the nest on a horizontal branch out from the trunk. The nest is constructed as a deep cup built of weed stalks, pine needles, twigs, lichen, and moss and lined with softer materials such as soft bark and cobwebs. Usually four eggs are deposited. The timing of incubation and first flight are not well-documented. The young may leave the nest about 10 days after hatching (Kaufman).
The Hermit Warbler is vulnerable to changes in forests in both its breeding and wintering areas. It is considered “a habitat specialist, has a narrow geographic distribution, and does not have a large population” (Reed in Pearson). Forest practices that include longer rotations between harvests on private land, reduced forest edge by keeping forest stands intact, and high canopy closure “…would likely benefit breeding, wintering, and migrating populations” (Pearson).
Photo Credit by Frode Jacobsen