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WILLIAM C. YOUNG
assist in tasks such as nest building, incubation, and care of the young,
which in most species are performed by the female. Many examples of
behavior of this sort are cited by Lehrman (7). He states that there are
no data bearing on the relationship between nest building and male
gonadal cycles to compare with those on the relationship of nest building
to the female cycle.
The relationship between testicular hormone and incubation by the
male is not clear. Again, citing cases from Lehrman's review (7), there
is at least one species, the black-crowned night heron, Nycticorax n.
hoactli, in which incubation by the male was induced by testosterone
(241). In the ring dove incubation by the male was induced by progesterone (242, 243), and in the short-tailed shearwater the lipid metamorphosis of testis tubules associated with the production of progestins
(244) coincides with the onset of incubation by the male (245). In
cases of this latter type it should be ascertained whether progesterone
acts directly or as an intermediary in the production of testosterone
(246).
Care of chicks by the domestic cock is inhibited by testosterone (7,
247). Clearly therefore in males of this species the action of some other
hormone is involved, and prolactin is indicated (247, 248). Nalbandov
doubts, however, that prolactin in itself brings about broodiness. Recalling the old observations that capons readily accept the care of young
chicks (249) and that prolactin inhibits secretion of follicle-stimulating
hormone (FSH) (250), he devised experiments leading to the conclusion that prolactin, by shutting off the secretion of androgen, creates
conditions whereby environmental stimuli essential for the brooding
response can act. A recent reconsideration of the problem (5) is centered
around the control of parental behavior in female birds, but the suggestions which emerge seem applicable to the male as well and in many
respects are more satisfying than the explanation advanced by Nalbandov (247) and Lehrman (7). The most important is that there is no
very precise hormonal condition which is a necessary prerequisite for
parental behavior; at the most a facilitating action would be claimed.
Eisner (5) notes after a thoughtful analysis of the problem, that the
hormones which in one species or another have been found to facilitate
parental behavior are prolactin, progesterone, deoxycorticosterone, luteinizing hormone (LH), androgen, and thyroxine. She suggests, however, that in the future attention should be given mainly to prolactin
and progesterone.
The behavior characteristic of the female consists of such elements
as oviposition, nest building, mating, incubation, and care of the young.
Territorial defense, courtship behavior, song, and male-like mounting
WILLIAM C. YOUNG
assist in tasks such as nest building, incubation, and care of the young,
which in most species are performed by the female. Many examples of
behavior of this sort are cited by Lehrman (7). He states that there are
no data bearing on the relationship between nest building and male
gonadal cycles to compare with those on the relationship of nest building
to the female cycle.
The relationship between testicular hormone and incubation by the
male is not clear. Again, citing cases from Lehrman's review (7), there
is at least one species, the black-crowned night heron, Nycticorax n.
hoactli, in which incubation by the male was induced by testosterone
(241). In the ring dove incubation by the male was induced by progesterone (242, 243), and in the short-tailed shearwater the lipid metamorphosis of testis tubules associated with the production of progestins
(244) coincides with the onset of incubation by the male (245). In
cases of this latter type it should be ascertained whether progesterone
acts directly or as an intermediary in the production of testosterone
(246).
Care of chicks by the domestic cock is inhibited by testosterone (7,
247). Clearly therefore in males of this species the action of some other
hormone is involved, and prolactin is indicated (247, 248). Nalbandov
doubts, however, that prolactin in itself brings about broodiness. Recalling the old observations that capons readily accept the care of young
chicks (249) and that prolactin inhibits secretion of follicle-stimulating
hormone (FSH) (250), he devised experiments leading to the conclusion that prolactin, by shutting off the secretion of androgen, creates
conditions whereby environmental stimuli essential for the brooding
response can act. A recent reconsideration of the problem (5) is centered
around the control of parental behavior in female birds, but the suggestions which emerge seem applicable to the male as well and in many
respects are more satisfying than the explanation advanced by Nalbandov (247) and Lehrman (7). The most important is that there is no
very precise hormonal condition which is a necessary prerequisite for
parental behavior; at the most a facilitating action would be claimed.
Eisner (5) notes after a thoughtful analysis of the problem, that the
hormones which in one species or another have been found to facilitate
parental behavior are prolactin, progesterone, deoxycorticosterone, luteinizing hormone (LH), androgen, and thyroxine. She suggests, however, that in the future attention should be given mainly to prolactin
and progesterone.
The behavior characteristic of the female consists of such elements
as oviposition, nest building, mating, incubation, and care of the young.
Territorial defense, courtship behavior, song, and male-like mounting