Borneo: The Symphony of the Rainforest

Grab your rubber boots and get ready to head deep into the rainforests of Borneo, where scientists are examining what sound can tell us about the animals that live there. A healthy ecosystem should be rich with sound - like a symphony! 

Scientists at The Nature Conservancy are trying to use the symphony of the rainforest to learn how to conserve it and keep the ecosystem healthy!

Planning an expedition into the forest takes a lot of preparation. Here at the Wehea Research Station, scientists are getting ready to pack their bags with all of the necessary equipment to place acoustic recorders in the rainforest.

This remote research station is where scientists stay while working in the rainforest. Electricity is provided by a few solar panels and a back-up generator. Water is piped in from the river and laundry is done by hand and hung to drip dry!

The numbered boxes on the table are acoustic recorders. They will be placed on trees and left to record the sounds of the forest for at least 24-hours. Before heading into the field, it’s necessary to make sure the recorders are ready to go!

The green, spiky fruit on the table is a rainforest specialty called durian. It’s one of several fruits that can be found growing in Borneo. Orangutans love to eat it, and while it’s sweet, it also smells a little like onion!

Scientists work with locals familiar with the forest to map out the best places to hang the recorders in order to capture a wide variety of habitats, animals, and sounds.

Scientists from The Nature Conservancy place an acoustic recorder the Wehea Protected Forest of East Kalimantan, Indonesian Borneo. The recorder will collect sound data for at least 24-hours.

It will record everything from the sound of raindrops to the elegant calls of forest birds to the loud whoops of gibbons. The sounds will be used to help measure biodiversity in a tropical environment. 

Biodiversity means the variety of life—and a healthy, biodiverse rainforest should be full of sound. 

Borneo is one of the most biologically diverse places on the planet and is home to many endemic mammals including the Bornean Orangutan, proboscis monkey, and the Borneo pygmy elephant. 

There are also more than 15,000 plant species, 420 bird species, 200 reptile and amphibian species, 200 mammal species, nearly 400 species of fish, and countless invertebrates. With all of these organisms a rainforest can get quite loud! 

Just as animals compete for resources like food and habitat, they also compete for space in the soundscape. Animals that vocalize evolve to occupy different niches or bandwidths in the soundscape so they can hear each other above all the sounds in a rainforest.

In the rainforest, rivers are like roads. The forest is so dense and full of plant life, it’s easier to use a river as a trail. Wildlife congregate around the river so it’s an excellent location to collect sound data. 

From here you can hear the faint, strange whoops of gibbons and the loud chirps of a squirrel among all of the other animals in the rainforest symphony.

The men in red shirts are local forest guardians. They are indigenous inhabitants of the island known as the Dayak. Their expertise is invaluable in navigating the dense forest. They also help protect the forest from illegal loggers and hunters.

This tree has enormous roots called “buttresses”. Because rainforest soils are nutrient-poor, with the greatest amount of nutrients near the forest floor, rainforest trees often have shallow root systems. 

The buttresses keep the tree from falling over while creating better access to nutrients.

Borneo’s rainforests are home to massive trees of all kinds, including those in the dipterocarp family—the main trees harvested by logging companies. Logging helps support the economy, but can be damaging to animal habitat. 

Additionally, rainforests are known as the lungs of the planet. Worldwide, they supply over 20% of the the planet’s oxygen, which is vital for living things. 

The Nature Conservancy is working with local logging companies to find methods that are less impactful to the rainforest and its inhabitants.

Here, you can see that only one tree has been cut down - that’s because the logging company is practicing reduced-impact logging where they remove only one tree at a time instead of clear-cutting an entire forest. 

Humans benefit from nature in many ways ranging from recreation to water filtration. These benefits are collectively called ecosystem services. Among the many ecosystem services provided, rainforests also sequester or store carbon, which helps to stabilize our climate. 

Some dipterocarps have seeds with more than two wings, and like the seed pictured here, they can have as many as five!

Borneo Orangutan Survival Foundation (BOSF) is one group working to rescue and rehabilitate orangutans so they can be released into the wild. Orangutan habitat is threatened by the encroachment of logging activities and other forms of development. 

The mission of the foundation not only includes caring for rescued orangutans, it also supports the education and empowerment of local communities to protect orangutans and their habitat. This is important because orangutans have a critical role in keeping rainforests healthy! 

Wild orangutans eat up to 400 types of food and require large expanses of forest to find enough to eat. During training, BOSF staff introduce orangutans to a wide variety of foods so they are able to find enough to eat if they are released. 

In fact, being able to identify at least 200 food types is a forest school graduation requirement!

By doing so, they create spaces where light can break through the forest canopy and shine on the seedlings below. This helps the forest grow!