Borneo’s critically endangered orangutans have experienced a mass die-off over the past 16 years. Research conducted on a population of orangutans in Borneo since 1999 has revealed that over 100,000 orangutans have died in the past 16 years, a figure which the researchers on the project have called “mind-boggling”. The research was carried out by scientists at the Max Planck Institute for Evolutionary Anthropology, and the results of the study were published in the journal Current Biology.
Only Half Of Borneo’s Orangutans Remain
The Bornean orangutan is found only on the island of Borneo and is already critically endangered, so this is especially devastating news for conservationists and researchers. Borneo is divided between three different countries, Brunei, Indonesia, and Malaysia. Borneo is undergoing heavy deforestation, as large sections of the jungle are cut down to make room for palm oil plantations and to make lumber and paper.
The Max Planck research team did research for years, doing many field surveys to gather data on the number of orangutans in Borneo. The researchers combined the 16 years worth of gathered field data to get an idea of how the orangutan populations changed over time. The data that the researchers gathered was combined with land use data to investigate possible relationships between land use and population numbers.
According to the researchers, only about 100,000 orangutans remain in Borneo, meaning that the Borneo orangutans have lost about half of their population over the past 16 years. The Borneo orangutans have been divided into 68 different “metapopulations” by the researchers. Metapopulations are small groups separated from each other orangutans by geographical features. Large roads, winding rivers, and deforested areas separate the orangutan groups from one another. While the researchers say there are 64 metapopulations currently in Borneo, only 38 populations are viable. Viable, in this case, means that there are 100 or more orangutans in the group and that the group has a likely future.
Deforestation And Hunting
The researchers say that deforestation is one of the primary causes of the dwindling orangutan numbers, as the habitat of the orangutans continues to disappear. When areas of Borneo are deforested, orangutans run out of food and can’t sustain themselves. Orangutans need a lot of food to survive, as a male orangutan can weigh up to 220 pounds and be almost 4.5 feet tall.
The researchers say that the exploitation of natural resources in Borneo is putting immense, unsustainable pressure on wildlife there, orangutans included. They predict that the deforestation of Borneo could lead to the deaths of another 45,000 orangutans in Borneo over the next 35 years.
Yet habitat destruction alone can’t explain the dramatic drop in orangutan populations. According to Maria Voigt, a scientist at the German Centre for Integrative Biodiversity Research, hunting is another driver of the orangutan die-off, possibly the greatest cause. The orangutans have disappeared in numbers that can’t be explained by only deforestation, implying that hunters are responsible for many orangutan deaths.
Orangutans like to feed on the crops grown in plantations, and in retaliation, many farmers or hunters kill them, according to Voigt. Voigt says that they knew orangutans would occasionally be killed by hunters, but that the impact of the threat had been underestimated. Orangutan populations can’t easily replenish their numbers, as it takes up to seven years for an orangutan to raise an offspring to adult age. Borneo is dotted by thousands of villages and small cities, meaning that even if every one of these settlements kills only one orangutan a year, that’s enough to kill off an entire population. The research team has called for leaders in Indonesia and Malaysia to denounce the targeting of orangutans and to take steps to protect them.
Other threats to orangutan populations include illegal pet trading and forest fires. Forest fires sometimes occur near villages and spread rapidly, destroying large sections of orangutan habitat.When combined with deforestation, orangutan habitat is rapidly disappearing.
While forest fires and indiscriminate deforestation have damaged orangutan populations, the highest absolute number of orangutans lost were lost in areas that were selectively targeted for logging operations. This is because while rates of decline were lower in those areas, more orangutans, in general, were found in areas where selective logging took place.
Young orangutans are also sometimes captured and sold as pets. Though the researchers don’t have any concrete numbers regarding how widespread the practice is, they know it does occur. Voigt says that the practice can be extremely damaging, because not only are young orangutans captured but mother orangutans are often killed so their young can be captured. This means that the females capable of sustaining the species are being killed off.
Protecting The Remaining Orangutans
Wildlife conservation groups and researchers are taking actions to protect groups of orangutans. One thing that is being done to reduce deforestation is to change how palm oil is grown and harvested. The World Wildlife Federation has said that it is important for companies to switch to sustainable supplies for palm oil, and that consumers should put pressure on companies to do so.
Sustainable palm oil growing practices include bans on deforestation and restrictions on creating plantations over peat soils. There is a certification system called the Round Table on Sustainable Palm Oil (RSPO) which monitors palm oil growing plantations and policies. An independent study done in 2017 found that deforestation for palm oil plantations has been substantially reduced, but that something must be done about forest fires and the clearing of peatlands.
In the meantime, steps are being taken to stop the killing of Bornean orangutans. Voigt says that the survival of the populations will depend not only on protecting the remaining stretches of orangutan habitat, but also on raising awareness about the killing of orangutans by hunters. Voigt says it’s important to drive home how even occasional killings could drive the species into extinction. Voigt believes the species can be saved if action is taken, as the orangutans have proven to be resilient.
They can walk on the ground for certain distances. They can also feed on plants like acacia or palm that are not their natural food. So they might be able to survive in landscapes where you have coexistence between development, in terms of plantations, and forests, as long as there is enough forest for them to survive and they are not killed.
As a stop-gap measure to help the orangutans, conservationists have created artificial forest canopy bridges, allowing orangutans to cross between previously isolated sections of forest. The artificial bridges are made out of the same materials that zoos use to create bridges and swings for orangutans in captivity. The hope is that these bridges can reconnect habitats which have been fragmented by roads and plantations, enabling orangutan populations to travel and spread once more.
*NOTE: New DOI's are registered weekly Friday and may not function until then.