Madrean Discovery Expeditions works to explore, study, and protect the Madrean Archipelago

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About Us:

 Madrean Discovery Expeditions, a signature program of, is dedicated to exploring, studying, and protecting the Madrean Archipelago, a series of unique ecosystems that range from New Mexico and Arizona to Mexico. Throughout the year, groups of uniquely qualified and multinational participants come together to record the plants and animals of this incredible region, focusing on the vastly understudied region of Sonora, Mexico. This information is then stored in an open-source database for the world to share, study, and use to preserve these ecosystems forever. 

Check out our flora and fauna database here:

Biodiversity records
International Participants
Volunteer Hours

The Madrean Archipelago

The Madrean Archipelago is a core area of the Mexican Pine-oak Forest global biodiversity hotspot, stretching from Arizona and New Mexico to the Sierra Madre Occidental in Sonora, Mexico. There are 55 isolated Sky Island mountain ranges in the Madrean Archipelago, 32 of which are in Mexico. Each Sky Island is an isolated mountain surrounded by desert and grasslands. Elevation and weather can be vastly different from one part of the mountain to the next, creating a plethora of miniature ecosystems. These rich habitats are home to a tremendous diversity of local and transient species, including half the bird species of North America, more than a hundred mammals ranging from elusive jaguars to endangered bats, and turtles, butterflies, lizards, and more.
However, until recently, there was virtually no information on the flora and fauna native to these Sky Islands in Mexico. This unmatched diversity demands study. Without data, research, education, and conservation efforts are very limited in size and scope. We must understand the complexities of the Sky Island ecosystems in order to protect them.


The Expeditions

Madrean Discovery Expeditions leads two major and multiple mini expeditions each year. These expeditions are a unique gathering of entomologists rubbing shoulders with herpetologists, botanists, ornithologists, students, policy professionals, and photographers; of Mexican nationals working alongside North Americans (and a smattering of Canadians).

So far, MDE has led five major expeditions to Sierra Juriquipa (August 2017), Cajón Bonito (April 2017), Sierra Buenos Aires (August 2016), Sierra Elenita (April 2016), and Sierra el Tigre (August 2015); and six minor expeditions to, Sierra San Jose (September 2017), Sierra Buenos Aires (July 2016), Sierra Elenita (August 2016), Rancho el Hoyo (October 2016), Rancho Pueblo Viejo (November 2016), and Sierra de la Madera (September 2015). Additionally, fully funded three Madrean Archipelago Biodiversity Assessments to Sierra de los Ajos (August 2014), Sierra Huérfana (April 2014) and Sierra la Púrica (August 2013). All together, these expeditions drive discovery at an incredible pace.

The Database

The Madrean Discovery Expeditions database ( is a free, publicly available database with 24,788 records of flora and fauna for Sonora. The database has been used for conservation, research, and education – serving as a resource for private reserves (Cuenca los Ojos Foundation, Northern Jaguar Reserve, Rancho Esmeralda, Rancho el Aribabi), two CONANP reserves (Ajos-Bavispe and Sierra de Álamos-Río Cuchujaqui), El Pinacate Biosphere Reserve, the proposed Sierra Huérfana CONANP Reserve, various areas proposed as state áreas naturales protegidas by CEDES, and more.  Additionally, this database has been used for records in various museums, scientific publications, and books on the dragonflies, amphibians and reptiles of Sonora.


Where We Work:

Donate Today

Since 2009, there have been 13 major expeditions. With your help, we can continue this tradition and ensure that our Sky Island ecosystems remain a global biodiversity hotspot. Every dollar raised will go directly toward funding the expeditions.

One time

Meet Tom Van Devender, Director

Thomas R. Van Devender (pictured right) was the Senior Research Scientist at the Arizona-Sonora Desert Museum for 25 years, where he conducted research on a broad range of natural history topics. He has published well over a hundred publications on a range of topics, including natural history, paleoecology, desert grasslands, desert tortoise ecology, local floras, ethnobotany, herpetofaunas and the Madrean Archipelago.

In May 2015, Tom began as the Director of Biodiversity Programs at, where he organizes biodiversity inventories to Sonoran Sky Islands in the Madrean Discovery Expeditions (MDE) program, which documents the diversity of animals and plants in the 35 isolated Sky Island ranges and complexes in Sonora, Mexico, and manages Project Wildcat, our predator projection program. From 2009 to 2014, Tom was the Manager of the Madrean Archipelago Biodiversity Assessment (MABA) project at Sky Island Alliance. At MABA and MDE, Tom has organized ten binational expeditions with large volunteer groups of taxonomic specialists, land managers, college professors and students, local residents, photographers, and journalists to make new observations in high-diversity areas in Sky Island ranges in Sonora.