Meeting Abstract

73.11  Sunday, Jan. 6  Experimental manipulation of workload in European starlings: effects on oxidative stress BOURGEON, S.*; WILLIAMS, T.D.; Simon Fraser University; Simon Fraser University sbourgeo@sfu.ca

Oxidative stress is widely held to be one of the main proximate mechanism underlying ageing and costs of reproduction. We examined the effects of experimental manipulation of breeding effort coupled with an antioxidant treatment, on oxidative stress in female European starlings (Sturnus vulgaris). Based on their initial clutch size, high quality females were given 3 chicks to raise (small brood size, BS) while low quality females were given 6 chicks to raise (large brood size). Half of the large BS birds were injected with vitamin C (an antioxidant) and half with saline, while females from the small BS group were injected with saline only. Oxidative stress was quantified by the ratio between total antioxidant capacity and total oxidative status. Unexpectedly, independent of antioxidant treatment, oxidative stress was significantly higher (by 40 %) in the small BS females during chick rearing. However, these females actually provisioned chicks at higher rates (due to lower contributions by their male partner). Furthermore, 81.8 % of small BS females returned to lay a second clutch of which 8 of 9 (88.9 %) raised chicks. Among the large BS group, 87.5 % of females injected with vitamin C returned compared with only 50 % of saline-injected birds. Among these returning females, 3 of 7 (42 %) vitamin C injected females raised chicks while only 1 of 4 (25 %) of saline birds did. Thus, antioxidant treatment appeared to influence female return rate and future fecundity. Given these short-term effects that we documented, in the context of costs of reproduction, we suggest that investigation of long-term effects of such an experimental manipulation will be important.