Habitat urbanization, nest defense and breeding success in the Oriental Magpie (Pica serica)

Abstract

Nest defense is one component of parental behavior performed to prevent the approaches of potential predators toward eggs and offspring. Although positive relationship between the occurrence and/or intensity of nest defense and the breeding success is expected, conflicting results have been reported. We hypothesized that habitat urbanization may confound the relationship between nest defense behavior and resulting breeding success. Based on the data collected during eight years, we explored the possibility that the relationship between nest defense behavior and breeding success may further depend on habitat urbanization in the Oriental Magpie (Pica serica). We found that magpie breeders with urbanized territories produced fewer fledglings. Furthermore, fledgling body condition was differentially related to the propensity of exhibiting nest defense behavior depending on habitat urbanization; among the breeders whose territories contain more urbanized areas, the breeders who exhibited more frequent nest defense behavior produced fledglings poorer in condition while opposite relationship was observed among the breeders with less urbanized territories. Our results suggest a possibility that habitat urbanization mediates the relationship between the frequency and/or intensity of nest defense behavior and the breeding success.