Abstract: The familiar spring sound of birdsongs heralds the onset of territory formation and a complex sequence of interrelated events that make up the breeding period. Such songs are an integral part of the repertoire of aggressive behaviors that males use to advertise and defend territorial boundaries and to attract mates (Fig. 1). It is well established that hormones, particularly testosterone, have stimulatory effects on aggression in reproductive contexts. The prevailing challenge hy pothesis asserts that testosterone and aggression corre late only during periods of heightened interactions be tween males. Under more stable social conditions, according to the hypothesis, relation ships among males are maintained by other factors such as social inertia, individual recognition of status, and territorial boundaries, and testoster one levels remain low. Recent re search has suggested ways in which the hypothesis should be modified or extended. In this article we will con_ sider the complexities of aggressive behaviors and their regulation, focusing specifically on species differences in territorial behavior of male birds as models for the multiple interactions of hormones, envi ronment, and behavior. The secretion of testosterone by interstitial cells in the testis is controlled primarily by a glycoprotein, luteinizing hormone, secreted from the anterior pituitary gland (Fig. 2). Testosterone stimulates the development of secondary sex characteristics such as wattles, combs, spurs, the cloacal protuberance (a copulatory organ), and
Publication Year: 1987
Publication Date: 1987-11-01
Language: en
Type: article
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Cited By Count: 501
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