Meeting Abstract

12.1  Thursday, Jan. 3  Species and reproductive stage-specific variation in avian acute stress response associated with urbanization in a desert environment. FOKIDIS, H.B*; ORCHINIK, M.; DEVICHE, P.; Arizona State University; Arizona State University; Arizona State University bfokidis@asu.edu

Cities now occupy vast areas of the earth�s landscape. The ability of organisms to occupy these human-dominated habitats may become an important factor governing their future survival. In the Sonoran desert, a region of high temporal resource variability, cities may provide more reliable food and water resources than native habitats to birds that are capable of exploiting them. However, birds living in urban areas are often exposed to frequent anthropogenic disturbance. Physiological and behavioral responses to varying resource availability or habitat disruption may be mediated through changes in hypothalamic-pituitary-adrenal axis activity. We measured baseline and acute stress-induced plasma corticosterone (CORT) in urban and rural populations of five passerine species that we sampled before, during, and after their breeding season in and outside Phoenix, Arizona. Within species, baseline CORT did not differ between rural and urban populations. Urban Abert�s Towhees and Curve-Billed Thrashers (desert natives) mounted greater stress responses than rural conspecifics. Urban, as well as rural Abert�s Towhees had CORT responses that differed from those of closely related rural Canyon Towhees, which exhibited a lesser stress response during breeding than during other stages. Rural House Sparrows and Northern Mockingbirds (urban generalists) showed greater stress responses than urban conspecifics, but only during breeding. Patterns of CORT secretion in birds across urban and rural gradients may be associated with a species-specific ability to exploit access natural or anthropogenic resources in cities. This ability may induce changes in stress responsiveness that contribute to individual success.