Luzon has the world’s greatest concentration of unique mammals

Based on their 15-year study published in the scientific journal Frontiers of Biogeography, a team of American and Filipino researchers concluded that Luzon Island, Philippines, has the greatest concentration of unique mammals in the world.

“At the time we started our study on Luzon in 2000, only 28 species were known from Luzon; by the time the project ended, the number doubled to 56 species,” said Lawrence Heaney, lead researcher, who is the Negaunee Curator of Mammals at The Field Museum in Chicago.  “Out of the 56 species of non-flying mammal species, 52 live nowhere else in the world. Of those 56 species, 28 were discovered between 2000 and 2015.  Nineteen have been formally described while nine more are in the process of being formally named.  These are truly staggering figures, equivalent to discovering almost 2 species of mammals per year, unequalled anywhere else in the world.”

Map of Luzon and adjacent islands, showing the locations of mountain ranges and mountains referred to in the text, and the locations of our intensive study areas (Source: “Mammals of Luzon Island” by Heaney et al 2016)

Two co-authors of the paper, Mr. Mariano Roy M. Duya and Ms. Melizar V. Duya, are researchers from the Biodiversity Research Laboratory, Institute of Biology, University of the Philippines Diliman (BRL, UP Biology).  Mr. Duya is also a UP Teaching Fellow while Ms. Duya is a senior biologist from the Diliman Science Research Foundation (DSRF).  They formed part of the field team that conducted the study over the past 15 years.  “It was a great learning experience in this journey of discovery. Our findings made us realize how unique and precious Philippine biodiversity is, its role in understanding biogeographic patterns and processes and its contributions to evolutionary studies,” the spouses Duya averred.

The support provided by the Philippine Department of Environment and Natural Resources, particularly the Biodiversity Management Bureau, the local government units and the local communities where the team worked, was invaluable, without which these findings would remain unknown to humanity.

About 103,000 square kilometers in size, Luzon is the largest island in the Philippines. For comparison, England is 30 percent larger while Madagascar is almost five times larger yet they contain much fewer unique mammals.  Indeed, every square meter of Luzon Island is prime biodiversity real estate.

Among the 28 new species discovered by the team are four species of tiny tree-mice with whiskers so long they reach nearly to their ankles, and five species of mice that look like shrews and feed primarily on earthworms. Most of the new species live in tropical cloud forest high in the mountains, where frequent typhoons can drop four or five meters (12 to 15 feet) of rain per year.

Mossy cloud forest on Mt. Bali-it, Kalinga Province, Cordillera Autonomous Region. Ferns, moss, orchids, and many other plants grow in profusion on the trunks and branches of mossy forest (also called cloud forest) where many of the unique Luzon mammals live. Much of the water that feeds the rivers on Luzon originates in these mossy cloud forests. (Photo by LR Heaney, The Field Museum)

“All 28 species discovered during the project are members of two branches on the tree of life found only in the Philippines,” according to Eric Rickart of the Natural History Museum of Utah. “There are individual mountains on Luzon that have five species of mammals that live nowhere else. That’s more unique species on one mountain that live in any country in continental Europe. The concentration of unique biodiversity in the Philippines is really staggering.”

Chrotomys mindorensis, the lowland striped earth-mouse which is a widespread species on Luzon provides benefits to farmers by feeding on giant earthworms that burrow holes in the walls of rice terraces, and on giant golden snails that damage rice crops. (Drawing by Velizar Simeonovski, The Field Museum)

Crateromys schadenbergi, bushy-tailed cloud rat. One of the most distinctive of Luzon mammals, these squirrel-like animals feed on tender young leaves in the tree-tops of cloud forest in the Central Cordillera. (Drawing by Velizar Simeonovski, The Field Museum)

Musseromys gulantang, Banahao tree mouse. Our project discovered four species of these tiny tree mice, most of which live on mountaintops in central and northern Luzon in forests dominated by oak trees. Their whiskers are so long that they reach to their ankles. (Photo by LR Heaney, The Field Museum)

Luzon has never been connected to any continental land—the species have been isolated, like the animals that live in Hawaii. But Luzon is much larger and at least five times older than the oldest island in Hawaii, and so has had time for the few species that arrived from the Asian mainland to evolve and diversify greatly.

“We wanted to learn more about the conservation status of these wonderful animals,” said Danny Balete, a Filipino research associate at the Field Museum 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. Quite a few of the species are seriously threatened by habitat loss and over-hunting, but none are yet extinct.” Luzon has a human population of about 50 million, including about 23 million in greater Manila, the country’s capital. “Protecting all of these species from extinction is going to be a big challenge. The good news is that when the native forest is allowed to regenerate, the native mammals move back in, and the pest rats get kicked out.”

“Learning about the tremendous diversity of mammal species present on Luzon is crucial to conservation efforts,” explained Heaney. “In order to be effective at conserving an environment, we have to know what’s out there.”

For more details, contact:

Dr. Perry S. Ong, UP Biology, Email: [email protected]

Ms. Kate Golembiewski, Field Museum of Natural History, Email: [email protected]