Birds of Indian Subcontinent

Plasma Estrogens and Brain Aromatase in Winter White-Crowned Sparrows

Publication Type:Journal Article
Year of Publication:1992
Authors:Schlinger, BA, Slotow, RH, Arnold, AP
Journal:Ornis Scandinavica
Date Published:1992
ISBN Number:00305693
Keywords:Emberizidae, Estrildidae, Poephila, Poephila guttata, Taeniopygia, Taeniopygia guttata, Zonotrichia, Zonotrichia leucophrys
Abstract:The expression of reproductive behaviors by songbirds outside of the breeding season suggests that these behaviors do not require gonadal hormones for their activation. However, many of these behaviors can be activated by estrogens, and castration of some songbirds does not eliminate estrogens from the circulation or eliminate estrogen-dependent effects on brain. Therefore, it is possible that reproductive and aggressive behaviors remain activated by endogenous estrogen when circulating androgens are low. We have measured plasma androgen and estrogen in a group of captive, winter White-crowned Sparrows Zonotrichia leucophrys. As expected, sex steroids were present at low levels in plasma. Nevertheless, estrogens (estradiol and estrone combined) were detected in the blood of most birds (adult males and immature males and females). In addition, we measured aromatase activity in brain and found high amounts of aromatase in the telencephalon, as has been reported for the Zebra Finch Poephila guttata. Because brain may be a source of circulating estrogen in songbirds, it is possible that the estrogen found in plasma of winter sparrows comes from brain and activates some reproductive behavior at this time of year.
Short Title:Ornis Scandinavica
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith