Data from: Private land conservation has landscape-scale benefits for wildlife in agroecosystems

Private lands contain much of the world's biodiversity. Conservation
of private land, especially agricultural land, is urgent yet challenging
because of the diverse priorities of landowners. Local effects of farmland
conservation programmes have been evaluated thoroughly, but
population-level response to these programmes may depend on effects that
extend beyond targeted land parcels. We investigated the landscape-scale
effects of a grassland conservation initiative, the Conservation Reserve
Enhancement Program (CREP), on a socially and economically important
gamebird, the Northern Bobwhite (Colinus virginianus). Barriers to
assessing population-level response to conservation include determining
the spatial scale at which a species responds to environmental change (the
scale of effect) and untangling density-dependent processes. We performed
point counts over 6 years at 247 sites with similar local CREP density but
varying landscape-scale CREP density. We used an open-population distance
sampling model to evaluate population response to landscape-level CREP
density and to forecast population densities under differing re-enrollment
scenarios. Our model included kernel smoothing techniques to estimate
scale of effect and an estimator of the strength of density dependence.
Density dependence moderated the effectiveness of the CREP, but overall
populations responded positively to increasing landscape-scale CREP
density. We estimated that at least 5% of the landscape needs to be in
CREP to meet population density goals of 0.25 bobwhite/ha. Conservatively,
we recommend 10% of the landscape to be in CREP. Our percent cover
recommendations are based on a distance-weighted average of CREP around
focal sites. Landscape-scale effects diminished with distance. For
example, assuming all else is equal, a CREP field 3000 m away had 88% less
of an effect on local abundance than a field 1000 m away. Fields farther
than 5000 m away had no effect on local abundance. Synthesis and
applications. Our study underscores the importance of a landscape-scale
approach to farmland conservation. Benefits of these programmes can extend
beyond the local scale, but their importance to local populations
diminishes with distance. Estimating the relationship between increasing
distance and the utility of conservation land to local populations could
provide land managers a practical framework in which to target land
enrollment to maximize biodiversity outcomes.