Dataset for Re-assessing the Status of High Desert Bird Populations of the Morley Nelson Birds of Prey National Conservation Area After 30 Years of Change

Abstract

Bird populations across North America are in decline. In sagebrush and other shrubsteppe habitats, habitat loss and other human pressures threaten bird communities. Our study assessed the status of a bird community at the Morley Nelson Snake River Birds of Prey National Conservation Area, a high desert site in southwestern Idaho, USA. Between 29 May and 14 June 2022, and 31 May and 19 June 2023, we conducted avian point count surveys at historical points that were surveyed two or more years from 1992–1995. We assessed changes in bird species detections, vegetation, and fire history between survey periods, as well as the relationship between vegetation, fire history, and species detections. We focused on the most numerous ten bird species in each time period, which included sagebrush obligate species, grassland specialist species, and species we considered open country generalists. Sagebrush cover decreased significantly at survey points between the historical and current survey periods, whereas annual herbaceous vegetation cover and fire occurrence increased significantly. Most species with at least 20 detections had different detection rates between time periods. Specifically, there were notable declines in detections of many species, particularly among sagebrush obligate species (Brewer’s Sparrow, Spizella breweri; Sagebrush Sparrow, Artemisiospiza nevadensis; and Sage Thrasher, Oreoscoptes montanus) as well as 2 common, generalist species — Horned Lark (Eremophila alpestris) and Western Meadowlark (Sturnella neglecta). Detections of several species increased from the historical to current survey period, particularly California Gulls (Larus californicus), Common Ravens (Corvus corax), and Long-billed Curlews (Numenius americanus). These 30-year trends highlight the perils of birds in sagebrush and shrubsteppe habitat and the relationship between bird population changes, loss of native vegetation, increase of invasive plant species, and more frequent fire