Landscape Patterns and Their Influence on Bird Communities Resulting from Agricultural Policies Promoting Shelterbelts in Eastern Nebraska

Evolving agricultural policies and technologies have influenced land management practices within agroecosystems, impacting available habitats for many species of wildlife. Increasing available wildlife habitat and enhancing habitat quality have become an explicit objective of existing agricultural policy. Thus, there is renewed focus on utilizing shelterbelt agroforestry systems as a tool to achieve conservation goals in the northern Great Plains. Two representative farms - a 700-acre dryland and 1260-acre irrigated farm were created in Saunders County, Nebraska. The Habitat Analysis and Modeling System (HAMS) was used to describe the composition and pattern of existing farms and surrounding landscape, as well as for the landscapes surrounding selected Breeding Bird Survey (BBS) routes. Simulated land use changes resulting from the implementation of two shelterbelt scenarios, Agricultural and Wildlife, were incorporated on each Representative Farm and surrounding landscape. Landscape variables which influence breeding bird species richness and community composition as determined from BBS routes were measured on simulated farm landscapes. A more heterogeneous landscape results from implementing either the Agricultural or Wildlife shelterbelt scenario. The percent total woods was confirmed to be a significant determinant of bird species richness on the BBS routes and therefore was important in influencing the bird community at both the farm- and landscape-level. Other landscape metrics which influenced the bird community composition on the BBS routes were woody edge percentages and edge density values. Policies promoting shelterbelts at the farm-level as well as on the agricultural landscape create edge habitats which ultimately favor birds within the Forest-edge/generalist and Grassland-edge guilds, while bird in need of conservation such as grassland-field species would potentially be negatively affected.