The effect of testosterone propionate on the black-crowned night heron

Abstract

Both sexes of the black crowned night heron undergo a marked increase in the pigmentation of lore, lower mandible and buccal cavity during the breeding season. The legs also undergo an intense vascularization which gives them a pink color. Gonadectomy causes a loss of these modifications. Injections of testosterone propic nate (Ciba) will produce these sexual changes in immature herons and in gonadectc mized adults. Estrogens (theelin, estrone acetate, amniotin and follutein) do not have this effect. It is concluded that the secondary sexual characters of the night heron are presumably produced by an androgen in both sexes. Both testosterone propionate and the estrogens cause an enlargement of the oviduct of the spayed night heron but only the estrogens produce a hyperplasia of its mucosa. The epididymides and their homologues are hypertrophied by testosterone propionate but not by the estrogens. Testosterone propionate will induce male sexual behavior in adult females or in immature birds of both sexes. Even in montlvold chicks it will make the voice more guttural and will induce territory defense, nest building, all male courtship ceremonies, copulation and, later, brooding. Differences between the sexual behavior of the adults seem regulated only by differences in the amounts of male hormone normally found in these birds. Estrogens alone fail to stimulate any breeding behavior in either sex. © 1940 by The Endocrine Society.