Bird communities of ponderosa pine forests: Impacts of patchiness, urbanization and resource availability

Fragmentation of forest environments has been shown to have profound effects on the animal communities using the forest patches. The forests near Boulder, Colorado, show a spatial pattern of patchiness closely mimicking that of human fragmented systems due not only to natural forest patchiness, but also to the combined effects of fire suppression and forest management. To determine if these "natural" patches follow patterns seen in anthropogenically created forest fragments, I examined the relationship between the bird community, spatial structure, and urbanization. Specifically, I looked at the abundance, diversity and resource use of birds using the ponderosa pine forest during the breeding seasons of 2001--2003.; I found that both patch size and urbanization in the surrounding landscape did affect species richness and diversity of the bird community. Individual species responded differently to size and urbanization but overall, ponderosa pine forest specialists showed the least response to these variables. Patterns of bird diversity and overall species richness closely mimicked patterns seen in human fragmented systems. Physical characteristics of forest plots showed patterns of soil temperature and ambient temperature that suggest effects of edge are important in these patches. However, vegetation did not vary in a way explained by patchiness or surrounding landscape. Foraging patterns by ponderosa pine forest birds did not shift in relation to resource availability and availability was not impacted by patchiness of the landscape. However, some species showed changes in foraging behavior in relation to patchiness.; In respect to bird communities, the complete picture developed from this study is one of isolated patches of ponderosa pine that harbor a variety of species adapted to using heterogeneous and even patchy environments. However, overall community patterns and responses of individual species suggest that this pattern is not universal and should be applied carefully. Patchy ponderosa pine forests of the Front Range display patterns that in some instances look like those seen in human fragmented systems, but display much higher complexity.