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Life's Diversity Abounds in Madrean Sky Islands

Madrean Album Skyislands

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(Image credit: Paul Condon/Sky Island Alliance)

The Madrean Sky Island Archipelago is a 70,000-square-mile (180,000-square-kilometer) region of northwestern Mexico, southwestern New Mexico and southeastern Arizona. The region is a blend of tropical and temperate climates and home to a biological diversity that exceeds any other region of the United States.

Madrean Album Summit

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(Image credit: A.J. Schneller/Sky Island Alliance)

Sky Islands are a class of continental terrain made up from a sequence of alternating valleys and mountains ranges. All sky islands have a stack of biotic communities that allow for vertical migration but the vast valleys between them act as a barrier preventing species from crossing from one mountain range to another.

Madrean Album Baboquivari

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(Image credit: Segio Avila/Sky Island Alliance)

Within the Madrean Sky Island Archipelago, the mountain ranges and valleys are basically parallel. The biotic communities found upon the mountains include montane coniferous forest, tropical deciduous forest and oak savanna with the key biotic community of the archipelago being the oak-pine woodlands. Short-grass prairie, subtropical thornscrub and subtropical desert communities populate the vast barrier valleys found between the mountain ranges.

Madrean Album Skyisland

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(Image credit: Louise Miszta/Sky Island Alliance)

Approximately 27 unique, biologically diverse sky islands are found within the border of the United States with such romantic and historic names as the Dragoon, the Baboquivari, the Huachuca and the Chiricahua Mountains .

Madrean Album Esmeralda

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(Image credit: Jessica Lamberton/Sky Island Alliance)

Within Mexico are found another 15 Madrean sky islands including the scrub oak-covered Sierra La Esmeralda Mountains. Conservation groups such as the Sky Island Alliance are working with landowners of northern Sonora to restore and manage the ecological treasures of the Mexican Sky Islands.

Madrean Album Chiricahua

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(Image credit: Jenn Falcon/Sky Island Alliance)

The Madrean Sky Island Archipelago is the physical and biological meeting point of two great mountain ranges the Rocky Mountains of the north and the Sierra Madres of the south. Upon these sky islands and in the vast valleys found between them are found half the bird species of North America, 29 species of bats, 104 species of mammals and more than 3,000 species of plants.

Madrean Album Graham

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(Image credit: Walt Anderson/Sky Island Alliance)

Mount Graham is the tallest of the Madrean Sky Islands, rising to an elevation of 10,720 feet (3,268 meters). Located within the Pinaleno Mountain Range, Mount Graham is home to the endangered Mount Graham Red Squirrel as well as the Mount Graham International Observatory.

Madrean Album Barrier

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(Image credit: Paul Condon/Sky Island Alliance)

The vast barrier valleys of the Madrean Sky Island Archipelago are parts of the Sonoran and Chihuahuan Deserts. Here over eons of time the valley floors have sunk to their present elevations creating miles and miles of desert habitat.

Madrean Album Sabino

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(Image credit: Patricia Hux/Sky Island Alliance)

Lush Sonoran Desert habitat is found in Sabino Canyon lies at the base of the Santa Catalina Sky Island. Visitors can hike in a forest of saguaro cacti in the morning and ski the slopes of Mount Lemmon in the afternoon.

Madrean Album Patagonias

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(Image credit: Erik Enderson/Sky Island Alliance)

The sky island environment of the Patagonia Mountains contains vast acres of lush grasslands over gentle rolling hills where many Old West gold and silver mining camps have turned into modern-day ghost towns. Such forgotten mining towns as Harshaw, Mowry, Duquesne and Lochiel can all be found in the hills of the Patagonias.

Madrean Album Huachuca

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(Image credit: Trevor Hare/Sky Island Alliance)

Natural riparian areas, such as this water sink found in the Huachuca Mountains provide a source of drinking water for the many species of animals that make their home in the Madrean Sky Islands.