The Tricolored Blackbird in Washington State: First Assessment of Status and Distribution

Abstract

Breeding of the Tricolored Blackbird (Agelaius tricolor) in Washington State was first reported in 1998, but since then the species’ status and population trends have been poorly documented. I reviewed available data and found reliable reports of breeding at six locations, all in the Columbia Basin ecoregion, and additional reports of nonbreeding birds in 11 counties statewide. Breeding colonies were small, averaging 34 birds. All colonies were in emergent vegetation, and birds moved among them over the 24 years covered by this assessment. The relatively arid environment of the Columbia Basin, the limited extent of wetlands suitable for nesting, and the intensification of agriculture, implying a reduction in insect populations, likely inhibit the expansion of the Tricolored Blackbird’s range in Washington. A systematic survey of known and suitable breeding locations within the Columbia Basin ecoregion, more intensive monitoring of colonies during the breeding season, an assessment of foraging habitats, and a review of the Tricolored Blackbird in the Washington State Wildlife Action Plan for 2025 should be the next steps in assessing the status and trends of the species.