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ARS Home » Pacific West Area » Burns, Oregon » Range and Meadow Forage Management Research » Research » Publications at this Location » Publication #410851
Research Project: Restoration and Conservation of Great Basin Ecosystems

Location: Range and Meadow Forage Management Research

Title: First record of tricolored blackbirds in Idaho

Author
item Olsoy, Peter
item SORENSON, KATIE - Non ARS Employee

Submitted to: Western Birds
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/24/2024
Publication Date: 3/1/2024
Citation: Olsoy, P.J., Sorenson, K.J. 2024. First record of tricolored blackbirds in Idaho. Western Birds. 55(1):43-50. https://doi.org/10.21199/WB55.1.3.
DOI: https://doi.org/10.21199/WB55.1.3

Interpretive Summary: Tricolored Blackbirds have declined by almost 90% in California, where most of the populations occur outside of small pockets in the Pacific Northwest, Nevada, and Baja California. Loss of wetlands that served as historical foraging and nesting habitats has led Tricolored Blackbirds to increasingly use agricultural landscapes including silage fields and cattle feedlots. In this paper, we provide a full account of the first documented Tricolored Blackbirds in Idaho from March to May 2023 and where they returned in November 2023. We found Tricolored Blackbirds at five locations in two counties, with all sites located at or adjacent to cattle feedlots. With documented range shifts northward, Tricolored Blackbirds will likely continue to expand into Idaho and use these agricultural habitats. Land and wildlife managers require additional information on wintering and potential breeding locations of Tricolored Blackbirds to make informed decisions.

Technical Abstract: Over 99% of Tricolored Blackbirds (Agelaius tricolor) occur in California. However, small populations persist in Oregon, Washington, Nevada, and Baja California. Loss of wetlands that historically served as foraging and breeding habitat has led to their increasing use of agricultural landscapes including silage fields and cattle feedlots. Here we provide the first documentation of the Tricolored Blackbird in Idaho (26 March–13 May and 3 November–16 December 2023), of up to 30 birds observed at five different locations associated with cattle feedlots, each 10–15 km apart, in Payette and Gem counties. Seven observations included recordings of vocalizations (3-23 April and 14 December 2023), largely coinciding with the final observations at each location, presumably before dispersal to breeding grounds. We consider three hypotheses to explain the apparently sudden occurrence of these birds, including their return to some of the same sites in November 2023: (1) a continued pattern of range expansion due to climate change; (2) an undetected long-term population due to low survey effort; or (3) a large-scale movement in response to flooding and extreme weather in the traditional range. We encourage continued monitoring and surveying of these locations in the coming years and surveying for both new wintering locations and for evidence of the Tricolored Blackbird breeding in Idaho.