Luzon, the largest island in the Philippines, has the world’s greatest diversity of unique species of mammals, according to a team of researchers from the Philippines and the US. Investigations show that 52 of the total 56 species of non-flying mammals inhabiting the island are found nowhere else on Earth.

As explained in the journal Frontiers of Biogeography, the 40,000-mile island (more than 100,000 square km) has never been connected to any continental island. This means that the animals have been isolated and the ones that arrived from the Asian mainland had enough time to evolve and multiply.

The research team asserts that they observed sped-up version of evolution. This happens when animals in an isolated location eventually form new species due to the lack of predators or competition for food sources.


This tree-dwelling mouse, which has whiskers that reach all the way to its ankles, is one of the 28 new species unique to Luzon discovered by Larry Heaney and his team in the course of this study. Credit: Larry Heaney, The Field Museum

The study started in 2000 and took 15 years to accomplish. Of the 56 species known to live in Luzon, the researchers discovered 28 new ones.

These include five species of mice that resemble shrews and consume earthworms and four species of small tree mice with whiskers that reach their ankles. Most of the animals reside in tropical cloud forests located high in the mountains, where typhoons usually cause four or five meters of rain annually.

Moreover, the researchers found that 57 species of bats live in Luzon, mostly in hot and humid lowlands. They found the lesser flat-headed bat or  lesser bamboo bat, a small bat that settles inside bamboo stems, as well as the golden-crowned flying fox, one of the heaviest bats in the world at more than one kilogram or 2.5 pounds.

“We also wanted to learn more about the conservation status of these wonderful animals,” adds Danny Balete, the Field Museum’s research associate based in the Philippines. “The Philippines is one of the most heavily deforested countries in the tropics; only about seven percent of the old-growth tropical forest is left. We learned that quite a few of the species are seriously threatened by habitat loss and over-hunting, but none are yet extinct.”

Although protecting the animals from extinction is a difficult task, the researchers say that they can always thrive once the forest is allowed to recover. Knowing all the animals inhabiting Luzon is the first step in making conservation efforts effective.