Can at-risk species serve as effective conservation surrogates? Case study in northeastern US shrublands

Targeted, single-species management and ecosystem-based management are generally considered disparate conservation approaches. In imperiled ecosystems, these approaches may be complementary, when habitat management for targeted at-risk species provides broad ecosystem benefits through an umbrella or surrogate species effect. In the northeastern United States, extensive management has been ongoing since 2011 to restore declining habitat for an at-risk shrubland habitat specialist, the New England cottontail (Sylvilagus transitionalis), with the goal that other shrubland-obligate wildlife will also benefit; yet the efficacy of these efforts has not been evaluated. In this study, we assessed whether habitat management targeting New England cottontail provides conservation benefits for shrubland-obligate birds. Specifically, we (1) identified shrubland-obligate birds that are indicative of the microhabitat conditions and habitat types suitable for New England cottontails, and (2) determined microhabitat and patch-level influences on shrubland bird occupancy at sites occupied by or managed for New England cottontail. Through avian point count surveys and indicator species analyses, we identified 12 shrubland-obligate bird species on patches occupied by New England cottontail and in microhabitat conditions suitable for New England cottontail. Occupancy models for five shrubland bird species further identified species-specific habitat associations. Generalized linear models showed that shrubland bird species richness was positively associated with herbaceous vegetation and low shrubs, indicating that shrublands managed for the purpose of cottontail colonization can also benefit a suite of shrubland birds before the habitat is dense enough to provide cover for cottontails. Our findings show that managing habitat for New England cottontail on a variety of site types can maintain a range of microhabitat conditions to support a high diversity of shrubland-obligate birds. These findings provide evidence for broad ecosystem benefits of managing for New England cottontail and exemplify the value of at-risk habitat specialists as conservation surrogates in imperiled ecosystems.See ReadMe and Metadata tabs of spreadsheets. Funding provided by: National Institute of Food and AgricultureCrossref Funder Registry ID: http://dx.doi.org/10.13039/100005825Award Number: 1006964Funding provided by: U.S. Fish and Wildlife ServiceCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000202Award Number:Bird point counts were conducted in 2015 and 2016 via the U.S. Fish and Wildlife Service landbird monitoring standard operating procedures. During each point count, the observer recorded all birds detected at distance bins of 0-25 m, 26-50 m, 51-100 m, and >100 m. We retained data from the 0-25 m and 26-50 m distance bins for analyses and excluded flyover detections. The raw data are provided by site, including detection covariates (temperature, time of survey, cloud cover, wind speed, background noise level, survey day, i.e., days since the start of the survey/breeding season). Vegetation data were collected at point count locations in 2017, at 20 sampling points placed in 4 cardinal directions within 50 m of each survey point. Measured habitat variables were averaged over the 20 sampling points and these data are provided in this dataset. For patch-level covariates (patch, woody vegetation species richness, and proportion of woody invasive vegetation), averages are given across the patch. Further details are provided in the metadata tab of the vegetation spreadsheet data