Apparent Movements of Birds Within an Urban Riparian Corridor During the Breeding Season

摘要

Riparian corridors provide diverse vegetation and a water supply that facilitates foraging and provides breeding areas for all sorts of wildlife. Increasing amounts of urbanization has adverse effects on wildlife that utilize riparian areas. Previous studies of habitat use by urban or riparian birds assumed that individuals were unlikely to move from a site once they settled in their breeding areas, however recent studies have shown that site use by birds may not remain static throughout the breeding season and movement may occur. I test the hypothesis that birds move throughout the breeding season leading to changes of habitat use as the breeding season progresses, especially with increasing amounts of human development and activity. I conducted point counts throughout the breeding season along the Boise River, ID. I placed species into 14 functional guilds to increase counts needed for analysis. Using detailed aerial photography, buffers were placed around each of the point count sites in ArcGIS and were hand digitized to assess the landscape composition of the area. At each site, vegetation metrics were taken within the riparian area to assess structure. This information was analyzed to give me models that estimated abundance and possible movement. Movement models outcompeted static models for every guild. Furthermore, I found evidence that birds not only moved throughout the breeding season but that movement is associated with aspects of urbanization and the riparian corridor at differing spatial scales. Within the urban matrix, I found that birds were more likely to move from urban areas into areas with larger amounts of riparian forest. In this study, I showed the importance of riparian habitat to wildlife, such as breeding birds, and the need to manage riparian areas that are becoming encroached by urbanization and increased land use.