On the hunt for fresh foraging sites, a male, at left, and his harem group amble over a stretch of coastal mudflats in Sarawak, where low tide has exposed mangrove roots. Travel on the ground is rare for proboscis monkeys, who live almost entirely in the treetops of Borneo’s riverine and mangrove forests and swamps. Though they travel a fair distance in search of food, they never stray far from water.