Previous studies have shown that before the arrival of humans, the island nation of Singapore was almost entirely covered in rainforests, with most of the rest being swamps or mangroves.
Since then, most of the island has been deforested. In addition to the loss of trees and habitats, other types of plants and animals that once called the island home have also suffered significant losses.
In the new study, the researchers note that over the years, little effort has been made to determine the rate of decline in biodiversity on the islands. To do this, they conducted research to learn more about what has happened in the last two centuries.
Researchers analyzed historical records detailing the island's flora and fauna as early as 1796. In total, they have found records of more than 50,000 plant species or animals, including 3,000 unique species.
As part of their analysis, they also used mathematical models to estimate what they described as a "dark extinction," in which a creature is thought to be extinct, but no work has been done to prove it.
They calculated that the island's overall extinction rate over the past 200 years was 37%. This count includes about half of the island's native butterflies, 90% of the birds, and about two-fifths of the bee species.
About 60% of large mammals have disappeared, including tigers and leopards.
Based on the results, the researchers then made estimates for the rest of Southeast Asia. They found that if deforestation continues at the current rate, about 18% of the region's living species will become extinct by 2100.