PARENT SESSION
Poster Session #43: Avian Ecology.
Thursday, August 9, 2001. Presentation from 3:30 PM to 5:00 PM. Exhibition Hall

Phoenix or Tucson: does landscape structure influence where Abert's Towhees choose to live?

Shochat, Eyal¹, Katti, Madhusudan¹, ¹

ABSTRACT- Habitat structure is often identified as a primary driver of bird distribution in urban areas. We demonstrate how landscape structure may override the influence of habitat through a case study of Abert's Towhees (Pipilo aberti) in Tucson and Phoenix, Arizona. Previous studies describe this species as common in urban habitats in Phoenix, but scarce in Tucson, although it is common in natural habitats surrounding both cities. An important difference between these cities is that several major riparian corridors run across Phoenix, but not Tucson. We tested the hypothesis that riparian corridors influence the distribution and abundance of Abert's Towhee in Phoenix. We estimated Towhee abundance from 51 point counts throughout the Phoenix area. We found that Towhees did not occupy all areas, and that their abundance decreased with distance from river. This suggests that riparian corridors facilitate towhee dispersal into urban habitats, and that the lack of such corridors in Tucson may explain their absence there. The lack of towhees away from riparian corridors suggests potential source-sink population dynamics along a riparian-urban habitat gradient. We suggest that studies on urban habitat use by bird species need to incorporate appropriately large spatial scales and landscape elements, since data from one city, as big as it may be, may represent pseudoreplication.

KEY WORDS: Pipilo aberti, urban, riparian, corridor