Interactive effects of habitat attributes and predator identity explain avian nest predation patterns

Abstract

Predation is the main cause of nest failure among birds. Habitat characteristics play a critical role in affecting nest predation by modifying nest conspicuousness and ease of access to predators. Here, using artificial nests containing a canary egg and a model clay egg we examined and compared nest predation rates and the principal nest predators in three different Patagonian forest stand types. Also, we evaluated how vegetation cover and nest height affected the different nest predators. We found lower nest predation rates in evergreen than deciduous forests, suggesting the forest type as a key factor modulating the risk of nest predation. We identified birds, an arboreal marsupial (Dromiciops gliroides), and mice as the main nest predators in the study area. These nest predators responded differently to the microhabitat conditions around the nest. Predation by birds was mainly related to nests placed closer to the ground, while marsupial nest predation was linked to greater shrub cover and mice showed no response to microhabitat conditions. Together, our results suggest that predation rates result from the interplay between large and small scale habitat characteristics, in addition to predator assemblages. Comparing specific predator-prey interactions is key for understanding the underlying mechanisms influencing nest predation.