220
WILLIAM C. YOUNG
Nest building and incubation behavior by the female are discussed
by Lehrman (7). The generally close temporal relationship between
ovarian follicular growth, sexual receptivity, and nest building suggests
that in many species of birds the physiological conditions leading to
nest building are the same as those associated with copulation and that
females are prepared for both types of behavior by substances produced
during maximum follicular growth. On the other hand, experimental
studies have been few and they have not led to anything definitive or
suggestive. Lehrman (7) induced nest building in intact female ring
doves by injecting diethylstilbestrol. Testosterone propionate was not
effective. What amounts to an opposite result was obtained by Noble
and Wurm (241). Injections of testosterone propionate into intact and
gonadectomized black-crowned night herons were followed by nest
building and courtship by the females as well as by the males. No phase
of the female behavior was induced by the preparations of estrone they
used. Near-lethal levels of estradiol benzoate induced nest building in
canaries during the nonbreeding season (286). The addition of progesterone or progesterone alone was without a detectable effect.
Incubation has long been associated with the hypophyseal hormone
prolactin, but the belief that this is the hormone specifically concerned
with the induction of incubation behavior (49, 287) has been questioned
and largely replaced by the view that an ovarian hormone or hormones
are more directly involved (5, 7, 243, 288). The basis for this change in
opinion has a long history. The amount of prolactin in the pituitary
glands of hens and ring-necked pheasants is small at the beginning of
incubation and rises sharply as incubation progresses (289-293).
This
finding is given meaning by the insightful contribution of Patel (294).
He showed (a) that the act of incubation in pigeons, rather than being
induced by prolactin, actually stimulates the secretion of this hormone,
and (b) that in males, at least, presence of the testes is necessary, not
only for the initiation of sexual behavior, but also for the functioning of
the pituitary as it produces prolactin in response to psychic stimulation.
Indications of the sequence of events in the female are provided by
an examination of the temporal relationship between ovulation and egg
laying, on the one hand, and incubation, on the other (7). Variation is
shown from incubation starting with the laying of the first egg, as in most
water birds and some songbirds such as the Florida Jay, Cyanocitta
coerulescens (295), and graceful warbler, Prinia gracilis (296), to
incubation which starts only after the last egg has been laid, as in the
snow bunting, Plectrophenax nivalis (297), and cedar waxwing, Bombycilla cedrorum (298). Lehrman (7) notes, however, that with respect to
hormonal changes associated with the last stages of follicular develop-
WILLIAM C. YOUNG
Nest building and incubation behavior by the female are discussed
by Lehrman (7). The generally close temporal relationship between
ovarian follicular growth, sexual receptivity, and nest building suggests
that in many species of birds the physiological conditions leading to
nest building are the same as those associated with copulation and that
females are prepared for both types of behavior by substances produced
during maximum follicular growth. On the other hand, experimental
studies have been few and they have not led to anything definitive or
suggestive. Lehrman (7) induced nest building in intact female ring
doves by injecting diethylstilbestrol. Testosterone propionate was not
effective. What amounts to an opposite result was obtained by Noble
and Wurm (241). Injections of testosterone propionate into intact and
gonadectomized black-crowned night herons were followed by nest
building and courtship by the females as well as by the males. No phase
of the female behavior was induced by the preparations of estrone they
used. Near-lethal levels of estradiol benzoate induced nest building in
canaries during the nonbreeding season (286). The addition of progesterone or progesterone alone was without a detectable effect.
Incubation has long been associated with the hypophyseal hormone
prolactin, but the belief that this is the hormone specifically concerned
with the induction of incubation behavior (49, 287) has been questioned
and largely replaced by the view that an ovarian hormone or hormones
are more directly involved (5, 7, 243, 288). The basis for this change in
opinion has a long history. The amount of prolactin in the pituitary
glands of hens and ring-necked pheasants is small at the beginning of
incubation and rises sharply as incubation progresses (289-293).
This
finding is given meaning by the insightful contribution of Patel (294).
He showed (a) that the act of incubation in pigeons, rather than being
induced by prolactin, actually stimulates the secretion of this hormone,
and (b) that in males, at least, presence of the testes is necessary, not
only for the initiation of sexual behavior, but also for the functioning of
the pituitary as it produces prolactin in response to psychic stimulation.
Indications of the sequence of events in the female are provided by
an examination of the temporal relationship between ovulation and egg
laying, on the one hand, and incubation, on the other (7). Variation is
shown from incubation starting with the laying of the first egg, as in most
water birds and some songbirds such as the Florida Jay, Cyanocitta
coerulescens (295), and graceful warbler, Prinia gracilis (296), to
incubation which starts only after the last egg has been laid, as in the
snow bunting, Plectrophenax nivalis (297), and cedar waxwing, Bombycilla cedrorum (298). Lehrman (7) notes, however, that with respect to
hormonal changes associated with the last stages of follicular develop-