Effects of grassland management on overwintering bird communities

Abstract

Birds that depend on grassland and successional-scrub vegetation communities are experiencing a greater decline than any other avian assemblage in North America. Habitat loss and degradation on breeding and wintering grounds are among the leading causes of these declines. We used public and private lands in northern Virginia, USA, to explore bene?ts of grassland management and associated ?eld structure on supporting overwintering bird species from 2013 to 2016. Speci?cally, we used non-metric multidimensional scaling and multispecies occupancy models to compare species richness and habitat associations of grassland-obligate and successional-scrub species during winter in ?elds comprised of native warm-season grasses (WSG) or non-native cool-season grasses (CSG) that were managed at di?erent times of the year. Results demonstrated positive correlations of grassland-obligate species with decreased vegetation structure and a higher percentage of grass cover, whereas successional-scrub species positively correlated with increased vegetation structure and height and increased percentages of woody stems, forb cover, and bare ground. Fields of WSG supported higher estimated total and target species richness compared to ?elds of CSG. Estimated species richness was also in?uenced by management timing, with ?elds managed during the previous winter or left unmanaged exhibiting higher estimated richness than ?elds managed in summer or fall. Warm-season grass ?elds managed in the previous winter or left unmanaged had higher estimated species richness than any other treatment group. This study identi?es important winter habitat associations (e.g., vegetation height and ?eld openness) with species abundance and richness and can be used to make inferences about optimal management practices for overwintering avian species in eastern grasslands of North America. © 2019 The Authors. Journal of Wildlife Management Published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.