Demographic aspects of the island syndrome in two Afrotropical Mastomys rodent species

► Density and survival are expected to be greater in island than in mainland populations. ► We tested these expectations in two African rodent species of the genus Mastomys. ► Capture-Mark-Recapture methods were used to estimate density, survival and seniority. ► Survival and densities were higher in island populations, especially in M. erythroleucus. ► We support demographic expectations of the island syndrome in an Afrotropical context