A new survey has discovered a huge amount of orangutans missed by past surveys because they were in strange places that scientists never expected they’d be able to survive in.

The survey now says there are 14,600 Sumatran orangutans, more than double what the last survey had totaled, according to a German Centre for Integrative Biodiversity Research statement. The last survey counted 6,600 orangutans in 2004.

Scientists don’t think that Sumatran orangutans suddenly doubled in size. More likely, past surveys had likely simply missed them. The species is still threatened by habitat loss and poaching, but at least the population is larger than had been thought.

The Sumatran orangutan is special because it is Asia’s only great ape. However, it exists only on the islands of Borneo and Sumatra in Southeast Asia, meaning that any upset in those habitats is likely to adversely affect them.

So where were these other Sumatran orangutans hiding? The scientists found them in places where they never thought to look, thinking that they wouldn’t be able to live there, such as higher altitudes of the mountains and in forests that had been logged but were in recovery mode.

“It was very exciting to find out that there are more Sumatran orangutans than we thought, but this does not mean that we can be complacent,” Serge Wich of Liverpool John Moores University said in a statement. “Numerous development projects are planned in the area that – if they are not stopped – could sharply reduce the number of orangutans over the coming years.”

He added: “We will need to continue to work together with the Indonesian government and other parties to ensure that this scenario will not happen. A difficult task, but we all hope that we can turn the tide for the Sumatran orangutan. We would like to see appropriate environmental impact assessments conducted for all developmental planning that concerns forests in the orangutan range so that disruption to their habitat may be avoided or reduced to a minimum.”