246,000 Trees Bring Endangered Proboscis Monkeys Home

When conservationists planted native trees along degraded riverbanks in Malaysian Borneo, they hoped wildlife might eventually return. Within just a few years, families of proboscis monkeys showed up and stayed.

The proboscis monkey, found only on the island of Borneo, is one of the world's most unusual primates. Males sport noses up to seven inches long, which help them attract mates and produce deep nasal honks that echo through riverside forests.

These monkeys are champion swimmers with partially webbed fingers and toes, crossing crocodile-filled rivers to find fresh leaves and unripe fruit. Every night they return to waterside trees to sleep, where the water helps protect them from tree-climbing predators like clouded leopards.

That dependence on waterfront forests nearly became their downfall. Over four decades, agriculture and logging destroyed roughly 80 percent of natural forest along critical habitats like the Kinabatangan River floodplain, leaving only 20,000 to 25,000 monkeys scattered in isolated fragments.

The Malaysian conservation group Hutan decided to rebuild what was lost. Since 2008, they've planted more than 246,000 native trees along riverbanks in protected areas and private lands, creating green corridors between habitat fragments.

The organization also partnered with farmers and even an oil palm plantation to add native trees to riverside property. A few years after planting, the monkeys came back.

"Today, we have a couple of proboscis families we see regularly," says Marc Ancrenaz, a wildlife veterinarian who co-founded Hutan in 1998. His team discovered something crucial: "These monkeys don't need a perfect, pristine forest."

The Ripple Effect

The success in Borneo shows that even heavily degraded landscapes can support endangered species with targeted restoration. Small restored sites are becoming stepping stones that allow wildlife to move between larger forest areas, expanding their range and genetic diversity.

The approach offers a model for conservation in human-dominated landscapes worldwide. When organizations work with local communities and landowners rather than against them, restoration happens faster and reaches farther than protected areas alone could achieve.

With agroforestry and strategic planting, fractured habitats can reconnect into functional ecosystems again.