Endocrinological and behavioral changes associated with the onset of incubation in the duck.

Plasma levels of prolactin were measured during the onset of incubation in ducks. A rapid rise in prolactin levels from a mean of 5.7 to 33.1 ng/ml occurred during the formation of the final 20% of the clutch; during which the females increased their nest-box occupancy from 9.9 to 22.2 hours per day. A pronounced decrease in plasma progesterone levels, but… CONTINUE READING