Dependence of spatial scale in landscape associations with cause‐specific predation of snowy plover nests

Abstract

AbstractUnderstanding relationships between habitat and ecological processes often depends on the spatial scale at which the landscape is measured. A common objective in studies of avian nesting ecology is to link habitat characteristics with nest predation for generating potential conservation and management strategies aimed at increasing avian reproductive success. Yet scale dependence likely plays a considerable role in these assessments, particularly when multiple species of nest predators are present. We identified nest predators of snowy plovers, a ground‐nesting shorebird, and modeled predator‐specific hazard rates of nest mortality in relation to the landscape at multiple spatial scales (200 m, 500 m, 1 km, 2.5 km, and 5 km) and at the nest site. We used a Bayesian latent indicator approach for weighting the influence of habitat across spatial scales and to gain insight into the hierarchical nature of how specific predators responded to the landscape when preying upon plover nests. We did not identify a common spatial scale that best predicted nest predation by all predators, though our results indicated that unfragmented playa and marsh habitats at large spatial scales reduced nest predation by all nest predators. Land cover features including grass, shrubs, human development, and open water elicited variable responses depending on the predator group, and predator groups responded at different spatial scales. Further, the spatial configuration of nests (nest dispersion) influenced nest predation by common ravens Corvus corax and foxes (kit fox Vulpes macrotis and red fox Vulpes vulpes), suggesting that certain predators develop a search image for nests. Our results illustrate that clarifying complex relationships between nest predation and habitat characteristics requires the incorporation of predator identity and scale dependence. Thus, management and conservation plans aiming to increase avian productivity by altering or restoring habitats will likely benefit from consideration of predator‐specific patterns at multiple spatial scales.