Meeting Abstract

P3.175  Sunday, Jan. 6  Do prolonged elevations of corticosterone influence the stable isotope ratios of blood in zebra finches? JOHNSTON, NR*; LOPES, PC; GOLDSMITH, GR; BENTLEY, GE; DAWSON, TE; Univ. of California, Berkeley; Univ. of California, Berkeley and GABBA, Univ. of Porto; Univ. of California, Berkeley; Helen Wills Neuroscience Institute and Univ. of California, Berkeley; Center for Stable Isotope Biogeochemistry and Univ. of California, Berkeley njohnston@berkeley.edu

Stable isotope analyses can be a powerful tool for determining animal diet, food web relationships and habitat quality. Changes in the stable isotope ratios of carbon and nitrogen are known to be associated with shifts in the quality, availability or source of food being consumed. To test whether other, previously unconsidered factors can cause changes in tissue stable isotope ratios, we implanted corticosterone capsules into female zebra finches (Taeniopygia guttata). Corticosterone is a hormone involved in carbohydrate metabolism often released in response to stressful stimuli. Prolonged elevations of this hormone can lead to catabolic effects on muscle protein. Blood samples for stable isotope analysis were collected prior to inserting the capsules and following 14 days of treatment. We also quantified food intake, body mass and plasma levels of corticosterone. We predicted that birds exposed to elevated corticosterone would demonstrate altered stable isotope ratios in blood despite the fact that food availability and quality remained the same. The experimental treatment induced reduced food intake and significant body mass loss, as well as a significant change in the carbon content (%) in blood plasma, indicating effects of corticosterone on bird metabolism. Although the treatment was maintained long enough for these birds to experience blood turnover, we found no evidence for the effects of prolonged corticosterone exposure on stable isotope ratios.