Non-invasive diagnosis of pregnancy in wild black rhinoceros (Diceros bicornis minor) by faecal steroid analysis

Abstract

The objective of this study was to determine whether faecal progestagenmeasurement could be used to diagnose pregnancy in wild black rhinoceros cows.Immunoreactive 20α-progestagens were measured in faecal samplescollected regularly (one or two times times per week) from pregnant andnon-pregnant wild black rhinoceros females (n =6)in Zimbabwe. Fresh dung piles deposited by the study animals were seriallysampled during prolonged periods of tracking with local game scouts. Sampleswere stored frozen, and dried prior to methanol extraction. Immunoreactivityin faecal extracts was measured with a 20α-dihydroprogesterone enzymeimmunoassay and was shown to reflect circulating progesterone concentrations.Mean concentrations of faecal 20α-progestagens during each month ofgestation were significantly higher than faecal concentrations in non-pregnantanimals (P<0.05), except during the second month ofgestation. Faecal 20α-progestagens remained 5-10 times higher thanconcentrations in non-pregnant animals from the 4th to 15th month ofgestation. It was concluded that regular non-invasive reproductive monitoringof black rhinoceros in the wild was possible and that pregnancy could beaccurately diagnosed from the measurement of 20α-progestagens in faecalsamples. The use of this technique in wild black rhinoceros populations willoffer new perspectives for in situ management of thisendangered species.