Meeting Abstract
34.6 Sunday, Jan. 5 09:30 Urbanization in relation to reproductive success, parental care, aggression, and corticosterone in song sparrows (Melospiza melodia) FOLTZ, S.L.*; DAVIS, J.E.; BATTLE, K.E.; ROSS, A.E.; MOORE, I.T.; Virginia Tech; Radford University; Virginia Tech; Virginia Tech; Virginia Tech sarahf8@vt.edu
As urban areas continue to grow, animals must adapt to the challenges and opportunities presented by these novel habitats or retreat to shrinking and fragmented rural areas. Responses to urbanization could include changes to behavior and physiology that may determine whether individuals succeed or fail at urban colonization. We compared urban and rural song sparrows (Melospiza melodia), a songbird common in both urban and rural areas, at 4 field sites (2 urban, 2 rural) in southwestern Virginia during the 2013 breeding season. We focused on relationships between nest success, parental care, male territorial aggression, and corticosterone, a hormone associated with energy balance and stress. In previous years, urban males from these populations have been more aggressive than rural males. We measured aggression via simulated territorial intrusions with recorded male song. We also measured plasma corticosterone before and after a handling stressor, nest visits by each parent during two 45min observations per nest between days 4 and 8 of the nestling period, and whether nestlings reached fledging age. Preliminary analyses suggest that urban nests were more likely to fledge and that likelihood of nest success changes during the breeding season. Urban males were significantly more aggressive than rural males, and there was a trend toward higher stressed corticosterone in rural birds, though baseline levels did not differ between the two groups. Males’ corticosterone and aggression were not related to their proportion of nest visits or to nest success, and nest visits did not differ between groups. These initial results suggest that urban areas may benefit some species via increased reproductive success.
