Climate change and habitat management implications for a declining grassland songbird in the North American Great Plains

Abstract

Accelerating climate change is affecting species worldwide, and is expected to have impacts on more than half of North American bird species. Some of the most rapidly declining birds in continental North America include those in the Great Plains, which are considered particularly vulnerable to climate-induced range contractions and shifts. Although grassland bird responses to habitat management are well-documented, less is known about their population responses to climate change and its interactions with their breeding habitat. We evaluated how climate and habitat management parameters influenced the abundance of Grasshopper Sparrow (Ammodramus savannarum), a declining Neotropical migratory bird that breeds on private conservation lands in the Platte River Valley, Nebraska, USA. To assess the potential impacts of future climate change on this species, we used a mark-recapture framework to sample birds at a total of 15 grassland sites subjected to various management actions including patch burning, cattle grazing, and haying over a 6 year period. We collected data for a total of 1194 birds over 388 netting days and used data to test sparrow responses to climate and management variables and their interactions via a series of candidate models created as generalized linear mixed models in R. Our top model incorporated the additive effects of interactions between grazing and burning histories with spring precipitation. Lower rainfall was correlated with higher sparrow abundance, likely due to its influence on foraging and food availability. The Grasshopper Sparrow population in this study was heavily affected by climate, so we expect ongoing climate change to have a strong influence on future population trends. The high conservation value of this area for a steeply declining grassland bird species highlights the importance of private conservation lands in mitigating negative anthropogenic impacts, including climate change, on wildlife, and the importance of adaptive management in maintaining populations of vulnerable species.