A systematic review and meta-analysis of variation in nest predation of ground-nesting birds.

Abstract

Predation and communities of predators of ground-nesting bird nests and fledglings have been studied across multiple groups of ground-nesting birds, such as waders, waterbirds, gamebirds and passerines, and habitats, but differences and similarities between groups are less studied. We synthesized data from 355 studies, mainly from North America and Europe, to investigate variations in predation rates of nests and fledglings of ground-nesting birds. The use of artificial nests to study predation has been a common practice, but the extent to which predation rates are similar to those of real nests has been a topic of discussion since the establishment of the method. Investigating effects on fledgling predation was not possible due to a lack of data. No differences in predation rates were detected for studies with or without invasive species or between waders, waterbirds, gamebirds and passerines, and predation rates were generally high for all groups. Artificial nests did have significantly higher overall predation rates compared to real nests, with an odds-ratio of 0.46 (95% CI: 0.35–0.61) of real nests relative to artificial nests. Mammals were the most frequent predator, being described in 50% of all studies, followed by avian predator species in 35%. Of mammals, the Red Fox Vulpes vulpes was described most frequently, in 19% of the studies. Unidentified predators were also prevalent in the literature (10% of studies), highlighting the common problem of not being able to identify predators of nests and fledglings. While the study identified a lack of data for some of the variables and regions, it does suggest that despite the differences in predator communities, predation has similarly high rates across ground-nesting bird groups. Further work is required to better understand predation, especially for fledglings.