Short-Term and Cumulative Life Stress in Mature Zebra Finches Based on Rearing Condition: Responses and Influence on Sexually Selected Traits

Stress responses, initiated by the hypothalamic-pituitary-adrenal axis (HPA axis), are essential for the survival of all animals when threatened by their environment. However, prolonged secretion of stress hormones can lead to several negative health consequences. Studies looking at individual differences in both short-term and long-term stress responses have suggested that early rearing conditions may contribute to an individual’s HPA axis activation, as well as developmental variations early in life. Royal, Hartly, and Parker (2002) found evidence that zebra finch chicks raised biparentally initially grew faster than chicks raised uniparentally. Despite these developmental discrepancies, singlemother nests were shown to raise better quality offspring and more physically attractive males. Additionally, previous research has found that chicks raised biparentally had elevated levels of corticosterone (CORT) compared to chicks raised uniparentally. In the present study, we examined whether these hormonal and physical differences continued into adulthood. CORT levels, via fecal assays, were studied in mature zebra finches before, during, and after experiencing a short-term stressor. Additionally, CORT levels were examined in feathers to represent cumulative life stress. Physical variations in male attractiveness were compared by measuring breast and cheek patches. No observable differences in sexually selected traits were found between uniparentally and biparentally raised males; thus suggesting that differences in attractiveness are derived solely from behavioral variations. Results from CORT assays for both short term stressors and overall life stress will be reported