(7) Huge herds of bison once roamed the northern half of Mexico, but today there are only a few hundred left, and they're considered an endangered species. A few Mexican ranchers still maintain wild herds and sell bison hunts. And Cindy Tolle, a conservation-minded rancher who operates on both sides of the border, has been a leader in restoring bison to Mexico. In 2004, Tolle moved several dozen from her South Dakota ranch to her nonprofit Tutuaca Mountain School, a 17,000-acre spread in Chihuahua, which lies within the 901,000-acre Tutuaca National Protected Area, created by the Mexican government in 1937 to protect the Yaqui River headwaters. That bison herd has grown to nearly 60 animals. Then, in 2009, Tolle helped broker a deal between Mexican and U.S. agencies to move another 23 bison from Wind Cave National Park in South Dakota to El Uno Ecological Reserve (#7 on the map), a 46,000-acre ranch in Chihuahua run by The Nature Conservancy's Mexican staff. That herd has grown to about 30 bison. The hope is that both herds will grow large enough that bison can be transplanted to other areas in Mexico. The El Uno ranch is within the 1.3-million acre Janos Biosphere Reserve, the Mexican government's first big effort to preserve grasslands (which have evolved with bison grazing). The Janos Biosphere Reserve also has the world's largest colony of black-tailed prairie dogs, black-footed ferrets, and Mexico's largest population of golden eagles.

(8) The famous Copper Canyon region (Barranca del Cobre) -- Mexico's combination of the Grand Canyon and Yosemite -- includes stretches of six rivers, the country's two highest waterfalls and a small national park (the 14,000-acre Cascada de Basaseachic). The Tarahumara Tribe earned its international reputation for cross-country ultramarathon running in these remote undeveloped canyons. Much of the region is not formally protected, though, and Tarahumara activists' resistance to logging old-growth forests has drawn worldwide attention. Efforts to develop a major resort complex are under way, including a combination gondola and bungee jump, an airport, luxury hotels and a golf course.

(9) Will the Mexican gray wolf ever not be a melancholy story? The last wild naturally occurring wolves in Mexico were trapped during the 1970s, to begin a captive-breeding program. Using some of the captives, the U.S. Fish and Wildlife Service has struggled for 14 years to re-establish the subspecies in Arizona and New Mexico. Meanwhile, Mexican President Felipe Calderón has pushed to re-establish the wolf in his country, and in October 2011, Mexico's CONANP released five captive-bred animals in the Sierra San Luis in northeastern Sonora. But ranchers on both sides of the border opposed the release in Mexico, and within a few weeks, four of the wolves were found dead -- killed by a poison that's used on rodents and other pests. Mexican officials reportedly plan more wolf releases, but specifics have not been made public.

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More info on conservation groups and conservation areas in Northwest Mexico

Mexican and U.S. groups working in the region

ProNatura Noroeste: A branch of Mexico's oldest conservation group based in San Luis Río Colorado, Sonora. It concentrates on purchasing conservation easements, and over the last 20 years, has bought 76 easements covering about 212,500 acres in six Mexican states, including Sonora and Baja California and parts of Chihuahua. Essentially, the easements are contracts with individual landowners or rural communes called ejidos, in which the group pays $20 to $80 per acre to landowners to prevent their land or water rights from being used for subdivisions, timber-cutting, grazing or other extractive activities.

Naturalia: From its headquarters in Mexico City, the group has worked with more than 30 other conservation groups, universities, and other research institutions in the Northern Jaguar Reserve in Sonora (see the separate explanation of the jaguar reserve). Also, Naturalia has worked with The Nature Conservancy's Mexican staff to establish a grasslands preserve, Rancho Los Fresnos, in Sonora, where it plans to someday transplant endangered prairie dogs. (See the separate description of Rancho Los Fresnos, #4 above).

Terra Peninsular: Based in Ensenada, a coastal city in Northern Baja California, the group seeks to protect Baja's coastal and mountain areas through land purchases, conservation easements and working with government agencies and landowners. It has established a 4,450-acre conservation easement at Rancho Rodeo del Rey, within an ejido in the Sierra de Juárez, about 50 miles south of the U.S. border, and is nearly halfway to establishing a 20,000-acre coastal sage scrub preserve in El Rosario, a city about 250 miles south of the border. It's also working with the Mexican government to try to establish a 150,000-acre, marine-terrestrial biosphere reserve in San Quintin Bay, about 200 miles south of the border, and hopes to upgrade protection of an existing federal reserve in the Sierra de Juárez.