Nest predation in Meadow pipits Anthus pratensis nesting in natural conditions

Abstract

Predation was the most important cause of nest failures in a population of Meadow Pipits Anthus pratensis breeding in a natural fen mire in Biebrza marshes (NE Poland). According to the Mayfield method, in two breeding seasons, predators interrupted 47% of all breeding attempts (95% confidence limits : 36%-55%). Other mortality agents (e .g . desertion of nests, flooding) eliminated another 5% of nests. Predators reduced production of fledglings by about 50% and introduced most of the variability in the number of fledglings produced in a single reproductive bout. There was a significant annual and within-season variation in the probability of nest predation. When seasonal changes in vulnerability were controlled for, the analysis revealed that in all stages of the breeding cycle the nest was equally likely to be depredated . A review of the data on survival of nests in four populations of Meadow Pipits, indicates that even though nest failure rates are similar (around 50%), the species must cope with different agents of mortality. In natural habitats predators pose a greater threat to nests than in habitats strongly modified by human activity