We studied the social organization of a colony of the fruit bat Carollia brevicauda in an artificial shelter in Bochalema, Norte de Santander, Colombia. Using a new type of marking and by focal sampling, one colony was observed from September 2007 to September 2008. It was determined that the social structure in the colony was integrated by four groups, which did not vary in structure over time. It was established that females were more faithful to the shelter than males. We assessed time budget dayly and there was that individuals hadx a 73.9 % time without any activity, followed by grooming with a 26.6 %, and females had higher activity than males, especially in dry season. We found that C. brevicauda has differences with records of C. perspicillata such as the fidelity of females and non-influence of lunar light over the hour of emergence from the refuge.