The Arabuko-Sokoke forest holds a number of mammals including elephants, buffalo, hippos, leopard, caracal & various antelope. The antelope include Bushbuck, Suni & four Duiker species including the fabulously rare Ader's Duiker (the others are Common, Blue & Red). Sadly without a prolonged period of time spent in the forest seeing any of these species is very unlikely (I did see an Elephant's backside as it headed off after pushing over a tree onto the track when we were driving back in the dark after an owl hunt). With some luck & good fortune both Four-toed Elephant-Shrew & Golden-rumped Sengi can be seen along the the edge of the forest tracks.
Primates are the most likely mammals to be seen however with Greater Galago being common at night whilst Yellow Baboons & Blue Monkeys are common during the day.