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

General and Comparative Endocrinology
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Abstract

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.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Patterns of maternal yolk hormones in eastern screech owl eggs (Megascops asio)
Series title General and Comparative Endocrinology
Volume 172
Issue 3
Year Published 2011
Language English
Publisher Elsevier
Publisher location Amsterdam, Netherlands
Contributing office(s) Patuxent Wildlife Research Center
Description 7 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title General and Comparative Endocrinology
First page 423
Last page 429