Prolactin and the Photoperiodic Gonadal Response in Several Avian Species

Abstract

A possible antigoriadal effect of prolactin was tested in several taxa of passerine birds. Prolactin partially inhibited gonadal growth induced by the photoperiod in Zonotrichia leucophrys nuttalli, Passer domesticus and Melospiza melodla merrelli. However, prolactin did not inhibit this gonadal re-sponse in Zonotrichia leucophrvs gambelii Zonotrichia albicollis and Junco hvemalis. A correlation was drawn between the presence of an antigonadal response and the migratory status of the birds. Those taxa in which there was no antigonadal effect by prolactin are all strong migrants. Those taxa in which an antigonadal effect was demonstrated are either non-migrants or weak migrants (M. melodla).