International audience ; Cercopithecus aethiops sabaeus have been known since 1906 to inhabit the mangroves of Southern Senegal, where they are called locally « mangrove monkeys ». An age-graded male troop of 33 individuals has been briefly studied in 1975 around the estuary of the Saloum river ; usually it split into smaller sub-groups or foraging parties during the day and even sometimes during the night. The troop’s home range averaged 138 ha. Territorial contests between adult males of adja cent troops have been observed ; these involved « loud barks », « chest exposure » and « penile display ». The troop studied spent 80 % of its time within the mangrove and only 13 % on the mainland. Sleeping trees can be located in both habitats, but mostly in the mangrove. Though C. a. sabaeus can swim, they prefer to cross mud flats and shallow water channels at low tide, or progress through the Rhizophora stilt-roots or pass from one tree crown to the other. The time-budget of the troop is given. The monkeys were observed feeding during 8.1 % of their activity time only. In 52 % of the cases they were seen hunting fiddler crabs ( Uca tangeri ) and 22 % of the cases eating Rhizophora flowers, fruits, shoots and young leaves, as well as the « pith » of young stilt-roots. Two different hunting techniques for crabs are described.