Island of Luzon: World’s greatest concentration of unique species of mammals

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golden crowned flying fox
A resting Acerodon jubatus (golden crowned flying fox), photo by Gregg Yan

A biological treasure trove better than Madagascar

A 15-year project done by a team of American and Filipino authors headed by Lawrence Heaney, the Negaunee Curator of Mammals at The Field Museum in Chicago has just published in the Frontiers of Biogeography that the 40,000 square mile Island of Luzon, in the Philippines has the world’s greatest concentration of unique mammals.

Triggered by the curiosity why most of the native mammal species in Luzon were unique to the island, the group has discovered that 52 out of the 56 species of non-flying mammal species(not including bats) are endemic to the island and can be found nowhere else in the world. Twenty-eight of these were just discovered during the project. Only 19 of these are formally described in scientific journals while nine more are still being studied.

Among the new discoveries were four species of small tree-mice that have whiskers reaching their ankles, and five species of earthworm feeding mice that looked like shrews were discovered.

long whiskered mouse | Island of Luzon: World's Greatest Concentration of Unique Species of Mammals
Long-whiskered mouse. LARRY HEANEY, THE FIELD MUSEUM

There are also 57 species of bats discovered that lived mostly on the hot and humid lowlands. Among this was one of the heaviest bats in the world called the golden-crowned flying fox. There is also the tiny lesser flat-headed bat that lives inside bamboo stems.

Because the island of Luzon has never been connected to the great Asian land mass, the species in the island has been isolated. this allowed them to “speed up” their evolution. This allows the animals to diversify, have special adaptations then eventually form a  new species. This is common is places where there are a few predators or competitors.

Also, the island of Luzon has mountain ranges covered with tropical cloud rain forest frequented by typhoons that can drop up to five meters of rain per year. These high mountaintops with isolated unique ecosystems that has a different evolutionary pressures than the lowlands are known as “sky islands“. 

This study has fueled the interest in conservation of the forest and the animals. Although these are not yet extinct, the loss of habitat and over-hunting threatens their existence.