Screening the foods of an endangered parrot, the kakapo (Strigops habroptilus), for oestrogenic activity using a recombinant yeast bioassay

In recent years the possibility of environmental oestrogens affecting the r eproduction of vertebrates has become an issue of both public and scientifi c interest. Although the significance of such chemicals remains controversi al there is clear evidence that, in some contexts, environmental oestrogens can influence the fertility of vertebrates. Highly endangered species repr esent a situation in which even modest reductions in the fertility of key i ndividuals may have implications for the survival of the entire species. Th is paper reports the screening of both natural and supplementary foods of t he kakapo (Strigops habroptilus), a critically endangered New Zealand noctu rnal parrot, for oestrogenic activity using a recombinant yeast based bioas say. Low levels of oestrogenic activity were detected in one of the 'chick- raising' foods, but no oestrogenic activity was detected in the adult suppl ementary foods. The oestrogenicity of a range of phytochemicals possibly as sociated with the kakapo natural diet was also examined. Two such phytochem icals, podocarpic acid and its reduced derivative podocarpinol, showed weak oestrogenic activity (approximately 10(-6) and 10(-4) of the activity of 1 7-beta -oestradiol, respectively).