Movements of black-capped chickadees (Poecile atricapillus) in a highly fragmented urban environment
Habitat fragmentation caused by human activities has been linked with extinctions of many species globally as pristine environments are divided into isolated patches, contributing to habitat loss and restricting gene flow. However, relatively little research has been done on the effects of fragmentation within an already urbanized landscape. Due to their high abundance and relatively large home ranges, black-capped chickadees (Poecile atricapillus) are an ideal species with which to study habitat connectivity within an urban setting. We tested the hypothesis that chickadee densities would be lower in more fragmented urban areas, using a Circuitscape model based on electric circuit theory and documented behavioural responses of chickadees to barriers in fragmented landscapes. The model simulated habitat connectivity across the small urban study area of Camrose, Alberta. This model was validated in the field using density surveys of chickadee populations in areas modelled as isolated against those modelled as connected. Due in part to the ‘stepping-stone’ effect of trees planted alongside roads, habitat connectivity was generally high across Camrose, with busy roads and unvegetated parks acting as major barriers. Chickadee densities were low in poorly connected areas, thus supporting the model and our hypothesis. The ability to model animal movements in urban centers is vital to inform city planning and management decisions, and to support local biodiversity.