Spatially Explicit Management Recommendation for Early Successional Bird Communities on Department of Defense Lands in the Mid-Atlantic Region.
Populations of many of the bird species that depend on early successional habitat in the mid-Atlantic region are declining and of conservation concern. The United States Department of Defense supports more open, early successional habitat than any other government agency in the region. Large, open grasslands and shrublands are regularly maintained on DoD installations for military missions such as airfields, firing ranges, armored vehicle maneuvering, and other purposes. However, not all open patches have the same flexibility for management due to requirements of the military mission. This assessment was conducted to determine the capacity and management flexibility of DoD installations to provide habitat for grassland and shrubland birds. A status assessment of early successional habitats on DoD lands was conducted by delineating individual patches of grassland and shrubland habitats from aerial imagery. Results of this assessment indicate that DoD installations support 1,223 patches of early successional habitat patches totaling 23,149 ha (57,178 acres). Projected estimates suggest that these patches can potentially support 213,000 pairs of breeding grassland and shrubland birds. Grassland and shrubland birds occupy distinctly different habitats due to differences in their overall habitat requirements. Grassland birds require open patches composed of only grasses and forbs and respond negatively to woody plant intrusion. Most grassland bird species are also sensitive to habitat area and found more frequently in large patches compared to smaller patches. Shrubland birds use later stages of open field succession and require woody vegetation in the form of shrubs and sapling trees. Shrubland birds are not as sensitive to habitat area as their grassland species counterparts and often found in small patches, along forest edges, and at canopy caps if dense shrub vegetation is present. Conversion of small grassland patches to shrublands is one recommended management scenario that can be broadly implemented across DoD installations to increase the overall land holding capacity of for early successional birds. This conversion allows small patches that represent poor habitat for grassland birds become quality habitat for shrubland birds. However, because small grasslands are not that common across DoD installations relative to other early successional habitats, this shift in management would only increase populations of shrubland birds by 2% of the current estimate. A comparison between 1996 and 2012 indicated relatively little change in the availability of early successional habitats on DoD installations. DoD lands provide some of the most expansive and stable patches of habitat for early successional birds of conservation concern in mid-Atlantic region.