Annual Changes in Fecal Sex Hormones with Corresponding Changes in Reproductive Behaviors in Thai Sarus Crane, Black-headed Ibis, and Lesser Adjutant Stork

Abstract

We monitored annual fecal sex hormones and reproductive displays of five individuals of males and females Thai sarus crane (Grus antigone sharpii), a flock of five males and females black-headed Ibis (Threskiornis melanocephalus), and five pair bonded lesser adjutant stork (Leptoptilos javanicus), all maintained in captivity at Bangprha Waterbird Breeding Research Center. Reproductive behaviors were observed during 0600-1800 h, for four days during the second week of each month and feces were collected monthly to determine annual male total testosterone (mTT) and female estradiol (fE2) levels by radioimmunoassay. Thai sarus crane exhibited a peak mTT in August following a fE2, with a surge in July. Black-headed ibis demonstrated a peak mTT in January prior to a fE2 with a surge in March. Lesser adjutant stork showed a maximal mTT coincidently with fE2 with a surge in October. Thai sarus crane frequently displayed courtship in May-October, corresponding well with higher mTT rather than fE2 levels. Black-headed ibis showed courtship-copulation displays in January, simultaneously with mTT, but not with fE2 surge. Lesser adjutant stork often displayed courtship-copulation in October-January, seemingly corresponded with higher mTT and fE2 levels during October-December and October-November, respectively. Male and female lesser adjutant stork displayed egg-incubation and chick-rearing behaviors in November-January and December-June, respectively. We suggest that mTT and/or fE2 apparently played an important role in regulation of courtship-copulation displays but did not relate to both egg-incubation and chickrearing behaviors.