Hermit Warbler migration tracked

Hermit Warblers spend their breeding season, April through July, in the Pacific Northwest, and their overwintering season in Mexico and Central America. Photo by Hankyu Kim.

"Hermit Warblers (Setophaga occidentalis) are an endemic-breeding species in the Pacific Northwest that winters in Mexico and the Central Americas. This species faces threats from mature forest loss and climate change throughout its range, but we know little about its migration ecology. To understand the annual movements of Hermit Warblers, researchers tracked 22 adult male Hermit Warblers. Birds showed shorter and faster movements during spring migration compared to fall migration. A high degree of mixing on the wintering grounds among birds from different breeding locations indicated low migratory connectivity. A compressed breeding schedule and departure of birds from the breeding grounds in early July may indicate that breeding is limited by a short window of favorable climatic conditions for breeding, which could signal heightened vulnerability under future climatic scenarios."

Kim, H., R. B. Siegel, J. L. Stephens, J. C. Hagar, B. J. Furnas, M.-S. Jeong, B. C. McComb, and M. G. Betts. 2024. Annual migratory movement, apparent molt-migration, migration schedule, and diffuse migratory connectivity of Hermit Warblers. Avian Conservation and Ecology 19(2):6. https://doi.org/10.5751/ACE-02622-190206