HANK MORGAN / SCIENCE PHOTO LIBRARY HANK MORGAN / SCIENCE PHOTO LIBRARY
Portrait of the biologist Nancy Czekala in her laboratory at the Center for Reproduction of Endangered Species at San Diego Zoo, California, USA. Czekala's research subject is the black rhinoceros Diceros bicornis. This African rhino- ceros is an endangered species in the wild. In captivity, most mature female black rhinoceros produce only one offspring. To better understand and treat this infertility in captivity, Czekala has established a method of monitoring reproduc- tive hormones of female rhinoceros by the sampling of saliva. Hormone levels in rhinoceros saliva provide a way of predicting birth by about 1 month and can detect pregnancy 13 months before birth.
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