Kaumanns, W., Singh, M., Schwibbe, M. 2013. Environmental change and housing conditions result in disappearance and return of reproductive seasonality in rhesus macaqes (Macaca mulatta). Current Science 105(4), 517-521.
Rhesus macaques in their natural environments, as well as in the free-ranging colony at Cayo Santiago, Puerto Rico are highly seasonal breeders. Many animal species lose breeding seasonality when brought under captive conditions. The present study that covers a period of 25 years between 1985 and 2010 reports a quick loss of reproductive seasonality in Group O of rhesus macaques after the group was shifted from Cayo Santiago to German Primate Centre at Gottingen, Germany in 1984, and maintained indoors with controlled temperature and day-length periods for about four years. We divided the study period of 25 years into five time-periods of five years each for analysis of the data. Over the subsequent years, births started to concentrate within only a few months indicating an increasing trend towards return of reproductive seasonality. This increase coincided with the increasing number of births in groups with outdoor facilities. Because other factors such as food, water, etc. were similar in indoor and outdoor conditions, we infer that the recovery of seasonality in the outdoor groups was due to the variations in temperature and photoperiod. We report here the presence of reproductive seasonality, its disappearance and return in the same colony and its descendents.