Meeting Abstract

65.2  Tuesday, Jan. 6  Hormone Levels in Laying and Non-Laying Female Eurasian Tree Sparrows on the Tibetan Plateau FOLTZ, S.L.*; DAVIS, J.E.; LEI, F.; WINGFIELD, J.C.; Univ. of California, Davis; Radford University; Chinese Academy of Sciences, Institute of Zoology; Univ. of California, Davis sarahlfoltz@gmail.com

Onset of breeding is energetically demanding, requiring precise modulation of multiple hormones, both before and after laying. Previous studies have shown that female birds also deposit hormones in their eggs that then influence development of the embryo. Such maternal effects may be particularly important in harsh and unpredictable environments such as the Tibetan Plateau, where sudden storms and extreme temperature fluctuations may interrupt the breeding season. The Eurasian tree sparrow (Passer montanus), is a resident of the Tibetan Plateau in towns and settlements. It is multiple-brooded, and to maximize breeding success across the entire season it must cope with unpredictable weather and unreliable food sources. Late season breeding is particularly risky due to the possibility of early snow storms shortening the breeding season. To determine potential mechanisms of coping with this severe environment, we measured corticosterone and testosterone levels of individual birds and eggs,comparing females with and without developing eggs. Additionally, we compared the hormone levels in yolks of developing eggs relative to each other and to the mother.