Application of modern endocrine methods to conservation biology

Abstract

Ishii, S. 1999. Application of modem endocrine methods to conservation biology. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban. Ostrich 70 (1): 33–38.

I report here on novel endocrinological methods originally developed for the artificial breeding of the Japanese Crested Ibis, Nipponia nippon. According to the most recent information. the only wild population in the world is one of about 60 individuals in Yang Xian, China. Captive populations of 54 and 17 individuals are located in Yang Xian and at Beijing Zoo, respectively and a single female of this species survives in Japan. Females of many birds stop breeding when they are brought to captivity. Hormone administration is considered to be effective in stimulating the breeding activity of such females. If the ovary of a captive female contains well-developed ova but does not ovulate, the problem is not serious. Ovulation can be induced by injection of gonadotropic hormone. However, if the ovary is regressed and contains no developed ova, the problem is serious. Until recently, no avian endocrinologist had been able to induce ovulation in hens with a regressed ovary. We developed a non-invasive method to assess the ovarian and testicular condition of birds by analysing gonadal sex steroid hormones in droppings. By using this method, we can decide whether the ovary contains developed ova or not and whether a male is sexually active or not. To reactivate a regressed ovary, we employed gonadotropin administration by means of the osmotic pump implantation in female Japanese Quail Coturnix japonica kept under short-days and then injected with the gonadotropin preparation once a day for several days. About 50% of the females laid an egg or eggs in response to the injection. Seven of the eggs were artificially incubated and two of them hatched. One of the two was revealed to be a male and fertile. The faecal sex steroid assays have been successfully applied to males of the Japanese Crested Ibis and Kakapo Strigops habroptilus in New Zealand. Although too late to apply the hormone administration method to the Japanese Crested Ibis for breeding, application of the method to the Kakapo is now being examined in New Zealand.