Mexico’s Overlooked Diversity

When we think of nations that are biodiversity hotspots, our minds instantly wander to places like Ecuador, Peru, Australia, Madagascar, DR Congo, and India. So, it may come as a surprise that the third largest total of mammal species of any country is none of those nations – rather, it is Mexico.

A number of factors account for this impressive diversity (536 species, or about 1/10th of the world’s total). As a start, Mexico is located at the meeting ground of North American and tropical species – thus, in the mountains of Chihuahua, you can see White-tailed Deer, Black Bears, Chipmunks, Bobcats, and other familiar North American fauna while observing Howler Monkeys, Jaguars, Agoutis, and Tamanduas in the rainforests of Oaxaca and Chiapas. An then there are marvelous places such as El Cielo Biosphere Reserve and the Sierra Gorda where these two groups of fauna intermingle, with Black Bears occurring alongside Spider Monkeys! Add to that some seriously impressive altitudinal variation (sea level along the coast to 18500 feet on the summit of Pico de Orizaba), 9300 km of coastline, and significant rainfall variation (practically nil on the Northern Deserts to more than 2.7 m in Tabasco) and you begin to see how Mexico is something of a living laboratory for evolution. To give some statistics, Mexico is home to 50% of all species of pocket gophers and 65% of all species of kangaroo rats and pocket mice.

And if that’s not enough, one only needs to turn to the 1000+ bird species present in the Mexico and the country’s position as the world’s second great center of conifer diversity.

However, Mexico’s wildlife is under threat. With all these distinct microclimates harboring unique species, it’s easy to understand that many can go extinct within the blink of an eye if sufficient action is not taken to protect them. Take pocket gophers for example – burrowing rodents with relatively limited dispersal ability and a preference for fertile soils. These characteristics put endemic pocket gophers’ distributions squarely in areas that humans favor for agricultural and urban development – the result: the endemic Big, Tropical, and Alcorn’s Pocket Gophers are all critically endangered while the endemic, monotypic Michoacan Pocket Gopher is endangered. As a further example, look to Heteromyids (Kangaroo Rats and pocket mice) – generally seen as pests in desert wastelands – the San Quintin Kangaroo Rat is likely extinct, the Oriental Basin Phillips’ Kangaroo Rat reduced to less than a tenth of its former distribution, the Dalquest’s Pocket Mouse threatened by agricultural expansion, and the Lined Pocket Mouse not definitively recorded in decades. As a grim reminder of our impact on the environment in such biodiversity hotspots, look to the stunning Imperial Woodpecker – a two-foot long bird with a dagger-like beak and an imposing front-face red crest – that is now almost certainly extinct, reduced to a ghostly memory in the old growth pine forests of the Sierra Madre Occidental, now a region actively destroyed every single day by opium poppy and marijuana growers affiliated with the infamous Sinaloa and Los Zetas cartels.

But despite some losses, there’s also reason for hope: Volcano Rabbits cling on in the heart of a megalopolis home to 20 million people; Mexican Wolves and California Condors have been successfully reintroduced to the Sierra San Luis and Sierra San Pedro Martir, respectively; and one of the world’s rarest pines, the incredible Martinez Pinon (Pinus maximartinezii), is the focus of a community conservation effort, the first of its kind in Mexico, in the Sierra Morones of Zacatecas. Recent surveys are revealing species previously thought extinct and expanding the ranges of others – take the rediscovery of the Big Pocket Gopher and range expansions of Rzedowski’s Pine as examples. If there’s one thing that can be said about Mexico’s wildlife, it’s that the nation’s biodiversity remains insufficiently known. This is a country where fabulous discoveries will continue to be routinely made as the nation’s remote mountains, deserts, and forests are opened up to science.

So maybe next time you’re thinking about enhancing your knowledge of the natural world, read a little about Mexico – I can guarantee you’ll be surprised by what you find. I sure was…

Venkat

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