Black-backed woodpecker abundance in the black hills

The Black Hills population of black-backed woodpeckers (Picoides arcticus) was petitioned, but deemed not warranted, to be listed as a threatened or endangered species under the Endangered Species Act and more information on their population size in the region is needed. Our objective was to map abundance and provide a population estimate of black-backed woodpeckers in the Black Hills and Bear Lodge Mountains of South Dakota and Wyoming, USA. We conducted 3,666 and 3,384 5-minute point count surveys from late-March to late-June in 2015 and 2016, respectively. We characterized vegetation around each point using geographic information system-derived landscape variables and fit 3-level hierarchical time-removal models in R package unmarked using gmultmix. The global abundance model received the most support and included year, latitude, and percent area of green trees, beetle-killed trees, dead trees, 1- to 2-year-old wildfire, 3-year-old wildfire, and 4- to 5-year-old wildfire. Points with high percent cover of beetle-killed trees had the greatest density of black-backed woodpeckers, followed by 1- to 2-year-old wildfires. After 4 years, areas burned by wildfire supported lower densities of black-backed woodpeckers than undisturbed forests. Mean density was 0.528 birds/km² in 2015 and 0.626 birds/km² in 2016. There were an estimated 2,920 and 3,439 black-backed woodpeckers in the Black Hills and Bear Lodge Mountains in 2015 and 2016, respectively. We suggest areas with high percent cover of beetle-killed trees may support high densities of black-backed woodpeckers and are important to sustaining populations when the availability of recent (<4 years old) wildfire is declining or scarce. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.