The effects of landscape composition and configuration on Eastern Whip-poor-will (Caprimulgus vociferous) and Common Nighthawk (Chordeiles minor) occupancy in an agroecosystem

Abstract

Agricultural expansion and intensification are some of the leading drivers of biodiversity loss globally. Effective conservation and management strategies for threatened species in agroecosystems require information on how these species are affected by (1) the amount and configuration of natural habitats, and (2) the type and extent of agricultural land covers. The Eastern Whip-poor-will (Caprimulgus vociferous) and Common Nighthawk (Chordeiles minor) are two nocturnal aerial insectivores in decline in North America, and have breeding ranges that include agriculturally dominated landscapes. We first assessed mean breeding occupancy of both species in eastern Ontario, Canada in 2016 using acoustic recording units at 127 sites. We then assessed the effects of landscape composition (forest, agriculture, wetlands, and urban covers), forest configuration (mean patch size, number of patches, distance to nearest patch), and agriculture type (perennial forages versus cropland) on Eastern Whip-poor-will occupancy. Eastern Whip-poor-will and Common Nighthawk occupancy in the study area averaged 0.244 and 0.064, respectively. We were unable to examine the relationships between landscape composition/configuration and Common Nighthawk occupancy because of small sample sizes. Nonetheless, Eastern Whip-poor-will occupancy was positively correlated with the amount of wetland cover and forest patch size, was weakly negatively correlated with urban land cover, and was unrelated to the type of agriculture. Our results highlight how the conservation of the Eastern Whip-poor-will in agricultural landscapes of eastern Canada would benefit from both wetland protection and the presence of larger forest patches, which can be accomplished through both forest protection and by allowing forest regeneration on abandoned lands.

Keywords

• aerial insectivores
• agroecosystems
• landscape composition
• landscape configuration
• occupancy
• scale of effect
• species at risk