Abstract:

Aims: Human disturbance strongly influences wildlife survival and distribution. Reproduction, a critical and vulnerable stage in the life cycle of Nycticorax nycticorax, is particularly sensitive to external stressors, especially human activity. Urbanization, one of the major forms of disturbance, can force birds to adjust nest-site selection in order to mitigate adverse impacts. However, such behavioral responses often vary with changes in the intensity of disturbance. Previous studies, relying mainly on single time points or widely spaced observations, have frequently overlooked these continuous and dynamic adjustments. 

Methods: During the 2023 breeding season, we conducted high-frequency, continuous monitoring of nest sites and breeding behaviors of Nycticorax nycticorax on the ecological island of East China Normal University’s Minhang Campus in Shanghai. We recorded changes in nest integrity and heron behaviors to examine responses to varying levels of human disturbance. 

Results: Nest distance from the pedestrian path decreased as human disturbance lessened. Similarly, average nest height declined under reduced disturbance. However, breeding success showed no significant correlation with disturbance intensity, nest distance from paths, nest height, or tree species used for nesting. 

Conclusion: Nycticorax nycticorax appear to mitigate human disturbance primarily through nest-site selection during the breeding season. These findings provide useful insights for the development of conservation strategies for urban birds during reproduction.

Key words: black-crowned night heron, bird reproduction, nest site selection, human disturbance, urbanization