I haven’t been to Cameroon yet, but I’ve included community reports from those that have.
Lobeke NP (Cameroon) & Dzanga-Sangha (Central African Republic), 2023: Pictus Safaris, 2 weeks & 38 species including – in Cameroon – Crowned Guenon and Bongo.
Cameroon, 2012: Rockjumper Tours, 3 weeks & 38 species (on a birding trip) including Mona and Putty-nosed Monkeys, Rusty-nosed Rat, African Pygmy Squirrel, Serval, Sand Fox, Marsh Mongoose, Red-flanked Duiker and Roan.
Cameroon, 2011: Rockjumper Tours, 3 weeks & 31 species (on a birding trip) including Mona and Putty-nosed Monkeys, African Pygmy Squirrel, Beecroft’s Anomalure, Sand Fox, Marsh Mongoose, Red-flanked Duiker and Roan.
The Congos, Cameroon and Gabon, 2009: Vladimir Dinets account of a week in each country. Species include: in Congo-Brazzaville – Black-legged Mongoose, Red-fronted Duiker; in Gabon – Northern Talapoin, Black Colobus, Red River Hog, White-collared Mongoose, Mandrill, and Cameroon – Drill, African Manatee and a swag of rodents, shrews and bats everywhere.