Guam, Marianas, USA Photograph by Michael Lusk   Western Micronesia: north of Papua New Guinea. Tropical and Subtropical Dry Broadleaf Forests   400 square miles (1,000 square kilometers) -- about half the size of Rhode Island Critical/Endangered

· A Visit to the Volcanoes
· Special Features
· Did You Know?
· Wild Side
· Cause for Concern
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A Visit to the Volcanoes

If you visit the Mariana Islands in western Micronesia, you'll get a fascinating geologic journey. In the southern part of the chain, you can see islands more than 30 million years old made of coral limestone and weathered volcanic rock. In the northern part, you'll see geologically young islands that include the still active Farallon de Pájaros volcano. You'll find that the vegetation differs quite a lot from north to south, for reasons of both geology and human activity.

Special Features

The Mariana Islands enjoy a tropical climate with little seasonal temperature change. Much of the year is dry, with heavy rains falling between July and October. Because of recent volcanic activity, there is little forest on the nine main islands of the northern Marianas. The local ironwood tree, known as gagu, is one of the first plants to colonize recent lava flows, along with a fern species. Elsewhere in the northern islands, you can find mapunyao trees, yonga trees, and a scrubby mixed-broadleaf forest. Most of the land in the southern islands is now agricultural or savanna.

	Brown tree snakes are originally from New Guinea and are thought to have arrived in the landing gear of airplanes.

Wild Side

Although there aren't many different species of plants on the Mariana Islands, you will find rare fire trees, 64 native ferns, and one native cycad. Among the many birds of the Mariana Islands are the rota bridled white-eye, the Mariana crow, the nightingale reed-warbler, and the endangered Micronesian megapode. Yonga trees produce bright blue berries that are a favorite food of fruit doves and other birds. Skinks race over rocks and logs. The threatened Mariana fruit bat feeds on the seeds of Terminalia trees and passes the seeds in its droppings as it flies, thus helping in tree dispersal and reforestation of the islands.

Cause for Concern

Humans have had an impact on the Mariana Islands for at least 3,500 years. Forests have been cleared for coconut plantations, fields, and gardens and logged for their timber. A lot of habitat was also destroyed during World War II. But today the biggest threat, especially to birds, is the introduction of non-native species. For example, the brown tree snake has already driven the Guam rail to extinction in the wild and threatens many other native bird species. Fruit bats are widely hunted for food, too.

For more information on this ecoregion, go to the World Wildlife Fund Scientific Report.