Westergaard, G. C., Izard, M. K., Drake, J. H. 2000. Reproductive performance of rhesus macaques (Macaca mulatta) in two outdoor housing conditions. American Journal of Primatology 50, 87-93.

We conclude that, for rhesus macaques, outdoor corral housing leads to better reproductive performance than does semi-sheltered gang housing, probably as a result of increased individual space and relaxation of intense social stressors.