Identifying important military installations for continental-scale conservation of marsh bird breeding habitat

Abstract

Degradation of wetland ecosystems has negatively impacted many species, perhaps none more so than marsh birds that breed in vegetative emergent wetlands throughout North America. The U.S. Department of Defense manages approximately 29 million acres of land within the continental U.S., and many military installations contain wetland complexes that may be important for wetland birds. Thus, failure to adequately manage habitat for marsh birds could result in species extirpations and additional listings under the Endangered Species Act, and may result in regulatory burdens that reduce military readiness. We conducted spatial analyses to identify important breeding habitat on > 500 military installations for 12 species of marsh birds, with the goal of identifying installations that are, and are not, likely to harbor breeding habitat for each species. We also sought to assess the local value of military installations for species of greatest concern by comparing habitat suitability within installations to that in areas directly adjacent to those sites. We built range-wide, spatially-explicit models of species distribution to project suitability of breeding habitat for marsh birds within and adjacent to military installations. Our results demonstrate that installations with the best marsh bird habitat are geographically aggregated (both among and within species), primarily at sites along the eastern seaboard and within the southern U.S. In addition, only a few sites appear to contain high-quality habitat for most species. Five or fewer sites contained most of the high-quality habitat for 9 of 12 species, whereas most of the high-quality habitat for remaining species was found at ≤ 10 sites. This work fills an information gap regarding the distribution of breeding habitat for marsh birds on military lands across the U.S., and should facilitate both strategic conservation of habitat over broad scales and the integration of marsh birds into management efforts at the site level. Our analyses also identify installations that are not likely to harbor breeding habitat for priority species, and thus should help minimize conflicts between needs of the military and marsh-bird conservation.