The November 1980 census suggests that population size and troop ranges have remained stable since 1972 and in a small area since 1963. This prolongs the apparent stability described by some authors, remarkable in a 200-ha reserve containing a maximum of 300 Lemur catta. However, inadvertent introduction of Lemur fulvus rufus and apparent loss of tamarind trees, as well as general genetic and biogeographic considerations, imply this stability may not continue. Berently underlines the need for long-term, widespread primate research and practical conversation.