Plant phenology is defined as the scientific study of the timing of recurrent biological events (flowering, fruiting, leaf shading and leaf flushing), the causes of their timing with regard to biotic and abiotic factors, and the interrelation among phases of the same or different species. Phenology has evolved over millions of years, but ecosystems degradation and climatic changes are affecting the native flora and fauna, and phenological patterns. However, there are relatively few studies on this subject worldwide. The Mauritian Wildlife Foundation initiated a study a decade ago to understand the natural food availability throughout the year across fragmented remnants and to manage supplementary feeding, which has been formalised since 2007. Phenology data has been collected for the period September 2007 to present at five conservation sites in Mauritius (four in the Black River Gorges National Park and the fifth, on the offshore islet of Ile aux Aigrettes) on 48 native and 16 introduced species. Significant correlations between phenological traits (flower budding, flowering, fruiting and leafing) to month, site and individual trees in declining order have been found. Phenology calendars have been produced for 43 native and 16 introduced species and these are useful tools for conservation of the species and for studying the impacts of climate change or variability on phenology. The effects of climate change are still unknown due to the paucity of data. However, initial analysis based on a restricted data set seems to indicate that rainfall variation does not significantly affect phenological traits for native and introduced species studied here.