Proboscis monkeys are unique large-nosed monkeys of Borneo found only in coastal mangroves and riverine forest, highly threatened by deforestation.
Deforestation forces groups to cross open terrain exposed to predators and heat stress. Isolated forest patches below minimum territory size cause malnutrition as preferred food trees are depleted. River crossings through degraded landscapes expose individuals to drowning and hunting. Captive proboscis monkeys are nearly impossible to maintain on their specialized diet, making them inappropriate for any captive setting.