For more than two decades, the Southern Region of the USDA Forest Service has adhered to the Migrant and Landbird Conservation Strategy to address conservation concerns arising from long-term population declines among many bird species. To accomplish this objective, the Forest Service has conducted a regionwide program designed to improve monitoring, research, and management of avian populations and their habitats. A team led by NE CASC principal investigators Thomas Bonnot and Frank Thompson has conducted the first comprehensive study analyzing the 26-year dataset generated by this program. Its results, which have been assembled in a new report, will help inform conservation and management efforts in the Southern Region.
The Forest Service conducts avian monitoring via 10-minute point counts from early April to late June across 15 national forest units. This study analyzed monitoring data collected from 1992 through 2017 to assess population trends and habitat associations of birds. It used time-removal models within a hierarchical Bayesian model framework to estimate species abundance by year, population trends, and abundance related to forest type and successional class.
All told, the monitoring effort yielded 82,367 point counts and detected 1,104,423 birds. In turn, the NE CASC study determined population trends for a total of 152 species and between 58 and 117 species per national forest. Seventy-five species had a majority of positive annual trends and 68 species had a majority of negative annual trends across all national forests.
The project estimated abundance in relation to forest type and successional class for 101 individual bird species. Thirteen species generally had greater abundances in late-successional classes and 29 species in early-successional classes. Twenty-one species were generally more abundant in specific forest types, and abundances of 38 species were more mixed or variable among forest types.