Research Article Winter Avian Community and Sparrow Response to Field Border Width ROSS R. CONOVER, 1,2 Department of Biological Sciences, Mississippi State University, P.O. Box GY, Mississippi State, MS 39762, USA L. WES BURGER, JR., Department of Wildlife and Fisheries, Mississippi State University, P.O. Box 9690, Mississippi State, MS 39762, USA ERIC T. LINDER, Department of Biological Sciences, Mississippi State University, P.O. Box GY, Mississippi State, MS 39762, USA ABSTRACT Transformations of agricultural practices in the southeastern United States have drastically reduced preexisting quantities of strip-cover habitat along field margins. The National Conservation Buffer Initiative has promoted the establishment of herbaceous field borders to restore wildlife benefits once provided by such habitat. We evaluated effects of native warm-season grass field border establishment and width on winter bird response. Narrow (approx. 8-m) field borders represented a marginal improvement to non-bordered margins that were cropped ditch to ditch, whereas wide (approx. 30-m) borders significantly enhanced total avian conservation value, abundance, species richness, and sparrow abundance compared to non- or narrow borders. Furthermore, presence of wide borders altered bird use of row-crop fields. We observed increased sparrow (Emberizidae) abundances in agricultural fields adjacent to wide borders, which likely resulted from enhanced waste grain foraging opportunities. Given these benefits to wintering farmland birds, we advocate the integration of herbaceous field border habitat in agricultural landscapes, particularly borders of enhanced width. ( JOURNAL OF WILDLIFE MANAGEMENT 71(6):1917–1923; 2007) DOI: 10.2193/2006-119 KEY WORDS conservation buffer, CP33, farmland birds, field border, Habitat Buffers for Upland Birds, Mississippi Alluvial Valley, National Conservation Buffer Initiative, wintering sparrows. Large-scale conversion of native grassland habitat to agriculture in the United States (Noss et al. 1995) has increased dependence of many grassland birds on agricul- tural landscapes for habitat (Hunter et al. 2001). Whereas agricultural growth previously benefited farmland birds through geographic range expansions (Hurley and Franks 1976), technological advancements have intensified agricul- tural practices (Vickery et al. 1999, Murphy 2003) and reduced non-crop habitat on field margins (Shalaway 1979). As grassland bird populations continue to decline (Herkert 1995, Peterjohn and Sauer 1999, Brennan and Kuvlesky 2005), field margin habitat during winter is increasingly important to prevent resource depletion from causing population bottlenecks (Payne and Wilson 1999). Intensive agricultural systems are unlikely to experience large-scale conversion of croplands to native habitat and, as such, wildlife habitat establishment must balance producer and wildlife needs (Peterjohn 2003). In 1997, the National Conservation Buffer Initiative (NCBI) was created to improve soil, air, and water quality, to conserve biodiver- sity, and to enhance wildlife habitat (Best 2000). Con- servation buffers represent a viable habitat option because they are easily integrated into production systems, provide multiple environmental benefits, and are more likely to be adopted by agricultural producers for economic reasons (Best 2000, Barbour 2006). Initial NCBI practices focused on water quality and, as such, buffers were restricted to down-slope field margins. In 2004, Habitat Buffers for Upland Birds (hereafter field borders) represented a new buffer practice under the continuous Conservation Reserve Program, with location flexibility to enhance wildlife habitat along upland field margins. Field borders are non- crop, herbaceous buffers that are typically incorporated with a preexisting field margin feature and provide nesting and foraging habitat, movement corridors, and escape cover for many avian species (Puckett et al. 1995, 2000; Marcus et al. 2000; Smith et al. 2005). Smith et al. (2005) also noted that escape cover in field borders might increase avian use of adjacent crop fields in close proximity, thereby increasing access to waste grain. Such benefits may be particularly beneficial to defray forage resource limitations for wintering birds (Davis 1973, Jansson et al. 1981, Lima 1990, Watts 1990). Field border establishment in the southeastern United States has specific potential to benefit temperate, short- distance migrant sparrows (Emberizidae) exhibiting declin- ing populations (Sauer et al. 2004). The Mississippi Alluvial Valley (MAV) physiographic region has undergone large- scale conversion of native habitat to agriculture (Noss et al. 1995, Rudis 2001), which likely increased grassland bird dependence on the landscape. The majority of overwintering sparrows in the MAV had negative population trends throughout North America from 1980 to 2003, and most sparrows inhabiting agricultural field edges in the Southeast are of conservation concern (Peterjohn and Sauer 1999). Unfortunately, the current paucity of research on wintering grassland birds in the southeastern United States (Marcus et al. 2000, Peterjohn 2003, Smith et al. 2005) inhibits development of efficacious management regimes. Field borders are increasingly popular among agricultural producers for their minimal impact on crop production (Davison 1941, Barbour 2006), attractiveness for northern bobwhite (Colinus virginianus), and potential to increase whole-farm profitability (Barbour 2006). The conceptual 1 E-mail: melospiza77@yahoo.com 2 Present address: Department of Natural Resource Ecology and Management, 339 Science II, Iowa State University, Ames, IA 50011-3221, USA Conover et al.  Winter Birds and Field Border Width 1917