Long-term population declines have elevated recovery of grassland avifauna to among the highest conservation priorities in North America. Because most of the Great Plains is privately owned, recovery of grassland bird populations depends on voluntary conservation with strong partnerships between private landowners and resource professionals. Despite large areas enrolled in voluntary practices through U.S. Department of Agriculture's Lesser Prairie-chicken (Tympanuchus pallidicinctus) Initiative (LPCI), the effectiveness of Farm Bill investments for meeting wildlife conservation goals remains an open question. Our objectives were to evaluate extents to which Conservation Reserve Program (CRP) and LPCI-grazing practices influence population densities of grassland birds; estimate relative contributions of practices to regional bird populations; and evaluate percentages of populations conserved relative to vulnerability of species. We designed a large-scale impact-reference study and used the Integrated Monitoring in Bird Conservation Regions program to evaluate bird population targets of the Playa Lakes Joint Venture. We used point transect distance sampling to estimate density and population size for 35 species of grassland birds on private lands enrolled in native or introduced CRP plantings and LPCI-prescribed grazing. Treatment effects indicated CRP plantings increased densities of three grassland obligates vulnerable to habitat loss, and LPCI grazing increased densities of four species requiring heterogeneity in dense, tall-grass structure (α = 0.1). Population estimates in 2016 indicated the practices conserved breeding habitat for 4.5 million birds (90% CI: 4.0–5.1), and increased population sizes of 16 species , totaling 1.8 million birds (CI: 1.4–2.4). Conservation practices on private land benefited the most vulnerable grassland obligate species (AIC_c weight = 0.53). By addressing habitat loss and degradation in agricultural landscapes, conservation on private land provides a solution to declining avifauna of North America and scales up to meet population recovery goals for the most imperiled grassland birds.

中文翻译：

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扩大私人土地保护以实现草原鸟类的恢复目标

长期的人口下降使草原鸟类的恢复成为北美最高的保护优先事项之一。由于大平原的大部分地区为私人所有，草原鸟类种群的恢复取决于私人土地所有者和资源专业人员之间强有力的伙伴关系的自愿保护。尽管有大片地区通过美国农业部的小草原鸡（Tympanuchus pallidicinctus) 倡议 (LPCI)，《农业法案》投资对实现野生动物保护目标的有效性仍然是一个悬而未决的问题。我们的目标是评估保护保护区计划 (CRP) 和 LPCI 放牧实践对草原鸟类种群密度的影响程度；估计实践对区域鸟类种群的相对贡献；并评估相对于物种脆弱性的保护种群百分比。我们设计了一项大规模影响参考研究，并使用鸟类保护区综合监测计划来评估 Playa Lakes 合资企业的鸟类种群目标。我们使用点横断面距离抽样来估计私人土地上 35 种草原鸟类的密度和种群规模，这些鸟类在本地或引入 CRP 种植和 LPCI 规定的放牧。α = 0.1）。2016 年的种群估计表明，这种做法保护了 450 万只鸟类的繁殖栖息地（90% CI：4.0-5.1），并增加了 16 个物种的种群规模，总计 180 万只鸟类（CI：1.4-2.4）。私有土地的保护措施使最脆弱的草原专性物种受益（AIC _c权重 = 0.53）。通过解决农业景观中的栖息地丧失和退化问题，私人土地保护为北美鸟类数量减少提供了解决方案，并扩大规模以满足最危险的草原鸟类的种群恢复目标。