An Ornithological Investigation of the Relationships Among Species Assemblages in Diverse Landscapes in Portland, Oregon

This study involves geographic variables of the urban landscape and how they affect bird species assemblage. I utilized bird point count data from observation sites in the Portland, OR metropolitan region provided by Portland Environmental Services. Species data and its relationship with environmental variables were evaluated using Bray-Curtis Dissimilarity measurements together with Non-metric Multidimensional scaling (NMDS) to provide a clear image of the spatial relationships between sites. Land classification, water and canopy in 500 m buffers were quantified in order to describe important geographic variability among collection areas of bird data. Patterns indicating spatial trends in the urban landscape emerged. Three groups of sites (Wetland, Built, and Forest) representing a tiered breakdown were formed to further inspect these trends and their effect on bird species communities. The breakdown trend extended from low-lying, heavily industrialized areas with extensive wetland or former wetland, to upland with less wetlands, some forest, and moderate-intensity suburban development at middle elevations, to heavily forested regions well upland in the large well-drained parklands and outer suburban terrain of the city. Bird species assemblages un-clustered across these trends suggest important landscapes for bird diversity throughout the city terrain, as well as interesting species associations. Unanticipated species finds, shifts in species diversity and indicator values among the clusters informs managers interested in maintenance and restoration of urban habitat in Portland