Black-capped Chickadee Abundance in a Fragmented Landscape

Abstract

Urbanization, the breaking of continuous forests into smaller, isolated patches, is a main driver of habitat fragmentation. Black-capped Chickadees, a species closely associated with mature forest structure, may be sensitive to these changes. Understanding local patterns in Helena, MT, USA is important because the mountain-valley landscape and patchy suburban development create fragmentation that differs from those documented in larger metropolitan systems. This study asks whether habitat fragmentation associated with urban development reduces Black-capped Chickadee abundance compared to continuous forest habitats surrounding Helena, MT. We anticipate a greater relative abundance in areas of contiguous forest. This study uses eBird observations of Black-capped Chickadees within the Helena area to generate broad estimates of relative abundance across urban, suburban, and intact forested habitats. We also expect a lower abundance in fragmented habitats due to the reduced cavity availability and increased edge exposure. This data provides a landscape view of how Chickadee abundance varies within habitat fragmentation, while allowing comparisons across multiple levels of development. The analysis follows established guidelines for controlling variation in the observer efforts, detectability, and sampling bias, ensuring that the abundance patterns reflect ecological differences rather than differences in observer behavior. The resulting estimates provide a broad baseline for addressing how chickadee abundance shifts across fragmented and continuous forest habitats.