eWestern Birds

The Quarterly Journal of Western Field Ornithologists

Vol. 52, No. 3
August 2021
Western Field Ornithologists

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Requiem for the Tricolored Blackbird in Mexico?
Richard A. Erickson, Horacio de la Cueva, and Enrique D. Zamora-Hernández

ABSTRACT: We summarize existing literature and document a recent steep population decline and range contraction in the Tricolored Blackbird (Agelaius tricolor) at the southern end of its range, in Baja California, the only state of Mexico in which the species occurs. From >1000 nesting birds using at least 14 sites south to 30° N around the turn of the 21st century, the population declined and contracted northward and upward in elevation to a single colony of ~150 nesting birds near the international border in 2019. Chronic drought, rising temperatures, and habitat losses due primarily to intensification of agriculture in Mexico are largely responsible for the decline, as in the core of the species’ range in California. Because of the reduction of breeding and foraging habitat, we fear the imminent extirpation of the species in Mexico.

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