Mexico’s Dying Desert

I recently spent 10 days traveling across Mexico documenting the country’s spectacular biodiversity, with an emphasis on endemic mammals and conifers. This is part 1 of a 4-part series from my travels…

Mexico is one of the world’s most important, yet least recognized hotspots of mammal endemism. High habitat heterogeneity and differences in climate result in a large diversity of species within small areas. Moreover, Mexico is the only country in the world in which the transition between temperate and tropical ecosystems is completely contained, resulting in a unique meeting ground of species from both regions. One of the most important areas of Mexico for endemic mammals is the Oriental Basin, a little-visited arid land near the borders of Puebla and Veracruz. And this was exactly a place I set out to visit.

I was headed for Totalco, a small town in Veracruz a few kilometers from the Puebla border, surrounded by fields of maize and potato and close to some of the last remaining natural habitat in the basin–remnant grasslands and inhospitable lava flows known as malpais covered in nopal, agave, and yucca.

This is exactly the habitat of some of Mexico’s rarest mammals, tiny relict populations of species that once had larger distributions throughout the Mexican plateau. Out on the plains live local subspecies of White-sided Jackrabbit, Long-tailed Weasel, and the endemic perotensis subspecies of Phillips’ Kangaroo Rat, Mexico’s smallest. The centerpieces of the region are its microendemics – species that evolved into new species through millennia of separation from close cousins on the Chihuahuan Desert and Altiplano–the hyperkinetic Perote Ground Squirrel (Xerospermophilus perotensis), the close relative of the ubiquitous Spotted Ground Squirrel of Northern Mexico and the Southwest; the amazingly long-eared Perote Mouse (Peromyscus bullatus), only known from a handful of localities with the exact same habitat, sandy, sparsely vegetated flats surrounded by malpais; the Oriental Basin Pocket Gopher (Cratogeomys fulvescens); and the almost unknown Nelson’s Woodrat (Neotoma nelsoni), a rare species closely related to the White-toothed Woodrat and isolated to a small region of malpais. Confusingly however, this species has also been recorded in remote cloud forest canyons near Coatepec, Veracruz. Either it’s got some amazing evolutionary plasticity or some specimens have been misidentified… There’s still a lot to learn!

I traveled to this unique and irreplaceable habitat with Juan Cruzado, a Mexican mammal expert with family from the area. Like other sites in Mexico, it was only through his local knowledge that I had a hope of locating the region’s rare mammals. But while we saw plenty of unique fauna, we also experienced more than our fair share of surprises, foremost of which was the devastating extent of habitat loss in the basin.

Juan hadn’t visited the site in 5 years, so we figure that this tour would be the perfect opportunity to find how the habitat had changed, for better or for worse, while he was gone. It was a real shock. The once expansive plains surrounding the cemetary, once a sure site to see the abundant Perote Ground Squirrels, were covered in houses, maize fields, and fences. Only a couple of acres of grassland remained, a glorified playing field surrounded on three sides by concrete wall and ravaged by goats and sheep. Herds of cows were a common sight in the area too. There were still rodent burrows, but it all seemed bleak at best.

I, however, was desperate to see the squirrel. So we figured our best shot was to drive the rough dirt road, the embankments of which were still pockmarked with ground squirrel burrows–and after one and a half hours of trying, I managed a brief glimpse. And that was it. Even after walking the road for another 40 minutes, nothing. While local shepherds insisted the little motitos (the local name for the ground squirrels) were still around, I suspect they’re confusing them with the abundant Rock Squirrels of the nearby malpais as I can’t see X. perotensis, a grassland species, withstanding so much pressure.

One the other side of town, where we searched for Perote Mice, Nelson’s Woodrats, and Phillips’ Kangaroo Rats, the situation wasn’t much better. 80 live traps caught only 1 confirmed Perote Mouse (despite very good habitat), 1 Kangaroo Rat, and not a single Woodrat (it hasn’t been caught in something like 10 years). While the situation is better at this site, where the best habitat is protected by areas of jagged, searing, inhospitable malpais, the grassy fringes are overtaken by zealously guarded fields of maize and potato. It’s only a matter of time before goats graze the site into oblivion.

Worse yet, there are no national parks in the basin–so these species have no habitat that will be protected from such disturbance. The fates of these species seem very bleak indeed, with no conservation efforts to speak of.

So what’s the future of the endemic fauna of the Oriental Basin? I hate to say it, but it’s not a good one. Maybe as soon as the next decade, the farms and settlements will close in and destroy the last habitat left. But we have to remember that not every place is like this–there are some sites that can be saved.

Going forward, let’s focus on protecting what we have, keeping the last expanses of habitat pristine before they too disappear. And for places like Totalco, maybe we can give the endemic mammals one last chance by captive breeding. It might be too late for conservation of this site’s mammals in the wild, but we can be mindful of the impacts of uncontrolled farming and settlement to prevent another extinction catastrophe like that in the Oriental Basin elsewhere…

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