Aim Elucidation of the influence of river systems on the distribution of lemurs.
Location Humid forests of Madagascar.
Methods We review the elevational distribution of Malagasy lemurs to address hypotheses of the role of rivers as physical barriers.
Main conclusions Rivers are barriers for some species. However, several lemurs have altitudinal ranges that are higher than the headwaters of a given river, and in such cases these species are able to disperse across the source.