Skip to main content
U.S. flag

An official website of the United States government

Patterns of maternal yolk hormones in eastern screech owl eggs (Megascops asio)

September 30, 2011

Owl clutches typically hatch asynchronously, and brood size hierarchies develop. In this study, we describe intra-clutch variation of testosterone, androstenedione, estradiol, and corticosterone in Eastern screech owl egg yolks. In order to assess whether these hormones may have originated in the follicle, we also characterize variation of testosterone, androstenedione, and corticosterone within the exterior, intermediate, and interior regions of the yolk. Concentrations of testosterone and androstenedione were distributed relatively evenly across egg lay order with the exception of first-laid eggs that had significantly lower concentrations of both androgens than eggs later in the laying sequence. Corticosterone and estradiol did not vary with laying order. Our results suggest that when food is abundant, yolk hormones are deposited in patterns that minimize sibling differences except to reduce dominance by the first-hatching chick. Testosterone and androstenedione concentrations varied throughout the yolk, while corticosterone was evenly distributed throughout the yolk. This supports a follicular origin for both yolk androgens, and an adrenal origin for yolk corticosterone.

Publication Year 2011
Title Patterns of maternal yolk hormones in eastern screech owl eggs (Megascops asio)
DOI 10.1016/j.ygcen.2011.04.001
Authors D. Caldwell Hahn
Publication Type Article
Publication Subtype Journal Article
Series Title General and Comparative Endocrinology
Index ID 70004613
Record Source USGS Publications Warehouse
USGS Organization Patuxent Wildlife Research Center