Fruit phenology of the Moukalaba-Doudou National Park (MDNP), Gabon is monitored as basic information on the fluctuation of food production for great ape populations. During the period from January 2003 to February 2007, we conducted a census on fallen fruits by the line transect method twice a month, in the process counting fallen fruit clusters and identifying fallen fruit species. We recorded 117 fallen fruit species during the study period. The majority of fruits came from trees. The number of fallen fruit clusters obtained in each census session correlated with the number of fallen fruit species found in the sessions. There was a marked seasonal pattern to fruit production, whereas the number of fallen fruit clusters as well as the number of species tended to be larger in the rainy season than in the dry season. Of the 31 major fallen fruit species, 15 species showed a fruiting peak in the rainy season, and five species peaked in the dry season, while 11 species showed no difference in fruiting abundance between the rainy and dry seasons. Candidates of keystone fruit species were identifi ed from species that fruit during the dry season. Five species of fruit, including the woody liana Cissus dinklagei, were constantly abundant, occurring in more than 70% of all census sessions. Four of them are important fruit food resources for the great apes. Several species including Klainedoxa gabonensis exhibited super-annual fl uctuation in their fruiting pattern. The existence of constantly abundant fruit species may have supported the high density of great apes in the MDNP.
