Nest distribution of magpies Pica pica sericea as related to habitat connectivity in an urban environment

Understanding the relationship between population dynamics and habitat connectivity is crucial for effective conservation and management of wildlife. In this study, we performed a graph-theoretical analysis to identify the relationship between nest distribution of the black-billed magpie Pica pica sericea and well-connected habitat patches. We analyzed 134 nest sites to determine environmental variables important for nesting magpies and identify habitat patches using a logistic model. Connectivity was estimated by Euclidean distance between habitat patches. A randomization procedure was implemented to verify the association between the nest distribution and the degree of habitat connectivity measured at multiple spatial scales. Preferred nesting habitat was areas close to the forest edge, containing more forest cover within 30 m of the nest. Connectivity analysis showed that the nest location was highly related to large clusters of habitat patches when patches are connected at large spatial scales. In addition, the nests in forest patches were close to grass patches with high connectivity. However, the size of habitat clusters adjacent to nests was much smaller than the average size of total habitat clusters across most scales, indicating that there are anthropogenic factors (e.g., effect of supplementary food in an urban matrix) affecting the distribution of magpie nests. Our results suggest that the distribution of magpie nests is related to landscape connectivity, which can be more clearly explained by taking into account the anthropogenic factors.