SALVANTE, K.G.*; WALZEM, R.L.; WILLIAMS, T.D.; Simon Fraser Univ., Burnaby, B.C.; Texas A&M Univ., College Station; Simon Fraser Univ., Burnaby, B.C.: Temperature-Dependent Reproductive and Behavioral Plasticity in Breeding Birds

Avian reproduction is generally timed to synchronize chick-rearing with periods of increased food abundance. Consequently, the energetically-demanding period of egg production may coincide with periods of lower food availability, fluctuating temperature, and more unstable weather. Little is known about the behavioral responses to forming and laying eggs at various temperatures or the physiological mechanisms underlying these responses. We therefore investigated whether varying ambient temperature during egg production influenced reproductive output (e.g., egg and clutch size, laying interval, laying rate) and daily food consumption in Zebra Finches (Taeniopygia guttata). Concurrently circulating levels of both generic very-low density lipoprotein (VLDL) and the yolk-precursor, yolk-targeted VLDL (VLDLy), and VLDLy particle size distribution were measured to determine changes in the female’s lipid metabolism in response to reproductive effort at varying temperatures. Female Zebra Finches were paired under each of three experimental temperatures: 7°C, 14°C, and 21°C. Preliminary analyses on females that bred while housed at both 14°C and 21°C found that egg laying was initiated three days later at 14°C than at 21°C (8 days and 5 days post-pairing, respectively). In contrast, there were no differences in egg size, clutch size, laying rate, mass at the 1-egg stage, or total plasma VLDL levels between 14°C and 21°C. Reproductive output and total plasma VLDL levels of females that lay while housed at 7°C will be compared to data from 14°C and 21°C. Similarly, comparisons between food consumption and VLDLy plasma levels and particle size distribution at each temperature will also be presented.