Reproductive success of songbirds and waterfowl in native mixed-grass pasture and planted grasslands used for pasture and hay

Abstract

Conservation of grassland birds in agricultural landscapes requires an understanding of the demographic consequences of nesting in native and planted grasslands. Much of the native grassland in agricultural regions has been converted to cropland. Subsequently, seeding cropland to perennial grasslands has become a common strategy to restore habitat for grassland birds, but these grasslands also may be used as hay and pasture forage for livestock. Our objectives were to determine (1) if the abundance of grassland songbirds and the reproductive success of songbirds and waterfowl varied between native pasture and planted grassland, and (2) if the amount of grassland in the surrounding landscape influenced the abundance and reproductive success of songbirds or the nest survival of waterfowl in native and planted grasslands. Our results suggest that planted grasslands used for pasture and hay in our region are likely ecological sinks for grassland specialist songbirds. Sprague's Pipit (Anthus spragueii) nested only in native pasture, and Chestnut-collared Longspur (Calcarius ornatus), Lark Bunting (Calamospiza melanocorys), and Baird's Sparrow (Ammodramus bairdii) were sometimes more abundant in planted pasture or hayfields, but fledged 1.4-4.5 times as many young per nest in native pasture. The reproductive success of waterfowl and grassland songbird generalists was similar in planted grasslands and native pasture. The abundance of all songbirds varied with the amount of grassland or cropland in the surrounding landscape, but landscape composition only weakly influenced the nest survival rates of 1 of 8 songbirds and 4 of 6 waterfowl species. Our results demonstrate that the preservation of native pasture is critical for the conservation of grassland specialists. Other grassland songbirds and waterfowl likely will benefit from the conservation of native and planted grassland and conversion of cropland to perennial grassland used for pasture and hay.