Lopé keeps patches of ice-age grassland inside its rainforest, and those openings are the only reason you see anything here at all. The savanna breaks the forest apart along the Ogooué in central Gabon, relic grass from a drier Africa that should have been swallowed long ago: 1,450 millimetres of rain falls on it a year, enough to grow rainforest straight across. Fire is what saves it: the park now sets controlled burns, because one patch left alone turned into young woodland within fifteen years. What the grass buys is sightlines. Forest elephants normally keep to thick cover — smaller than savanna elephants, with straight tusks pointing downward — and almost nowhere else in their range can you watch them out on open ground. You take a place above the clearings towards dusk and wait for the treeline to open.
The mandrills are the other thing the openings give. A horde is made up of females and their young. The adult males, the ones with the red and blue faces, join only while the females are cycling, from about June to September — which is when troops of 600 and more spill across the grass near the research station. Researchers argue that is what drove the males' extreme colour: with no lasting bond between partners, the signal has to do all the work. Guides track radio-collared animals from the station, and when a horde finally crosses open savanna the forest seems to empty into the grass. Short walks and dugout trips along the slow Ogooué reach outcrops where iron points hammered spirals, circles, lizards and double-bladed throwing knives into the stone about 2,000 years ago. Nobody signed or dated them; archaeologists placed them by matching the designs to pottery nearby. The same trees here have been checked for ripe fruit since 1986. In the 1980s roughly one in ten carried any; today it is closer to one in fifty, and between 2008 and 2018 the body condition of Lopé's fruit-eating elephants fell by 11 per cent. The openings that let you watch them are also how anyone can see that they are getting thinner.