Abuko is a square kilometre of gallery forest in The Gambia, half an hour from the beach hotels. A few steps past the gate the hot open track turns into a shaded trail and the air drops several degrees around you. A stream keeps it green in a country of savanna, and the tree crowns join into a roof over the path. Most of what lives here is up in that roof rather than at eye level. The green monkeys are the exception. Troops of them work the trailside trees and drop onto the path without hurrying away. Ten minutes on a bench and the troop carries on around you: infants riding, adults squabbling, one sentry watching the trail.
An elevated hide looks straight down on the reserve's main pool. Water is scarce in the country outside, so everything comes to this one. Crocodiles bask on the bank, bushbuck edge out to drink, monkeys forage along the far shore, and a kingfisher holds station over the creek. With a still half-hour the whole cast assembles in a single view. Walking straight through, you will have seen a green pool. The red colobus are harder. They are rust-red against the green and stay high, giving themselves away by a sudden crash of branches over your head. Leaves are all they eat, so they need mature trees, and this is one of the last places in the country where they are easy to find. More than 270 bird species have been recorded in this square kilometre, and from November European migrants join the residents at the water. The Gambia's chimpanzee project began in these trees in 1969 with orphans taken from traffickers, though the species itself had been gone from the country for decades. Two kinds of crocodile share the pool, and one of them almost nobody sees. The West African dwarf crocodile stops growing at about a metre and a half, hunts crabs and frogs in shaded water instead of ambushing anything large, and comes out at night. It is down there in the same pool the cameras are pointed at.