Invasive species face new environmental conditions in their areas of introduction. A correct timing of reproduction is crucial for the successful adjustment of individuals to their environments, yet the temporal aspects of the niche are a neglected subject in the study of biological invasions. When introduced, exotic species could successfully invade new habitats by making use of ecological opportunities, e.g. empty temporal Eltonian niches. Specifically, they may achieve this via conservatism of their native reproductive phenology and/or via plasticity in their reproductive timing. Here we compare the reproductive phenology of a marshland passerine community composed of five successfully established tropical exotic species and twelve coexisting Mediterranean native species along four consecutive years. Both groups showed large differences in their phenology, with exotics reproducing along more months and later in the year than natives. One exotic species even breeds only in late summer and early autumn, when virtually all natives have ceased breeding and when overall bird abundance as well as primary production in cultivated areas (rice fields) were highest. Nonetheless , estimates of population sizes and juvenile survival rates in the study area suggest that late breeding is not maladaptive but instead highly successful. The striking difference in reproductive timing suggests that the exotics may be taking advantage of a vacant Eltonian temporal niche, possibly generated by high resource availability in human-transformed habitats (rice fields and other croplands) in the study area. This study highlights the need to also consider the temporal aspects of the niche when studying invasions.