Abstract
The detailed reproductive physiology of cockatoos based on gonadal hormone dynamics is unclear. In this study, we aimed to investigate ovarian activity by monitoring urofecal sex steroid hormone profiles in a captive female white cockatoo (Cacatua alba) and to noninvasively reveal basic reproductive physiology by comparing the hormone profiles with the laying dates, body mass changes, and molt progress. Urofeces were collected regularly for approximately 4 years from one female that frequently laid unfertilized eggs under single-rearing conditions. Urofecal progesterone (P(4)) and estradiol-17β (E(2)) were measured by enzyme immunoassay. In addition, body mass and the number of fallen feathers were measured periodically. The urofecal P(4) concentration peaked at an average of 17.7 days after the start of the rise in urofecal E(2) concentration, and egg laying began on the day after the peak urofecal P(4) concentration. The clutch size was usually two eggs, with an average interval of 4.5 days between eggs in each egg-laying cycle. There was a significant correlation between the dynamics of E(2) concentration in urofeces and body mass. The results strongly suggest that E(2) and P(4) reflect the follicle growth and ovulation status, respectively, and that noninvasive monitoring of hormone dynamics using urofeces can accurately capture ovarian activity in the white cockatoo. Furthermore, changes in body mass can predict follicular growth, and reproduction and molt are antagonistic.