Résumé
Most wild Sahelian rodents display a seasonal reproduction that is usually related to rainfall, hence resources availability. Mastomys natalensis is a well-documented and major pest rodent species. In East Africa where it occurs outdoors, the species is characterized by marked population cycles. In contrast, it is mostly associated with humans in West Africa, and appears to live strictly indoors in the Sahel. Here, we have monitored the proportions of M. natalensis juveniles and sexually active adults within the city of Niamey, Niger. Our survey clearly shows that M. natalensis reproduces all year long, with no detectable seasonality. Altogether, our data confirm that reproduction may shift from seasonal to continuous when conditions are more favorable. They also suggest that the urban environment may represent an extreme habitat where resources are permanently available. From the perspective of rodent control in Niamey, our results highlight the need for a constant management policy that should be performed by public authorities.