Vesper Sparrows (Pooecetes gramineus) are found throughout the northern half of North America and Canada. In the Pacific Northwest, breeding populations of Oregon Vesper Sparrow (Pooecetes gramineus affinis), one of four subspecies, historically spanned from southwest British Columbia, through western Washington and Oregon, to northwestern California. Breeding Oregon Vesper Sparrows have been extirpated from British Columbia and California, and their overall abundance has declined at a rate of about 5% per year since 1968 – equivalent to losing over 90% of the population from 1968-2015. The current population size is estimated to be fewer than 3,000 individuals. Due to these dramatic changes, the subspecies has been petitioned for listing as endangered or threatened under the U.S. Endangered Species Act.
Collaborators are conducting field research to determine why this species has declined, and what can be done to turn these negative trends around. Klamath Bird Observatory, American Bird Conservancy, and Center for Natural Lands Management are tackling this unique opportunity to study Oregon Vesper Sparrows together, throughout the subspecies’ breeding range, in order to develop strategies for stabilizing and recovering populations.