After playing, feeding, and socializing in trees all day, some ring-tailed lemurs (Lemur catta) take their nightly respite in caves, according to a new study in Madagascar Conservation and Development. The findings are important because this is the first time scientists have ever recorded primates regularly using caves. “The remarkable thing about our study was that over a six-year period, the same troops of ring-tailed lemurs used the same sleeping caves on a regular, daily basis,” said the lead author, Michelle Sauther, with the University of Colorado Boulder.