Black‐backed woodpecker abundance in the Black Hills

Abstract

ABSTRACTThe 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.