Cuatrocienegas: The Endangered Coahuilan Box Turtle
The University of Texas at Austin. [Sounds of walking and water sloshing.]
"There's a turtle over here," says Ron Oldfield. "There's one here too," says Dean Hendrickson.
[Sounds of walking.]
"We’ll start getting into pretty good concentrations, I imagine,” says Hendrickson. “Yea, actually I can see about 6 now,” says Oldfield.
By 10 a.m. in August, the blazing Chihuahuan Desert sun is already turning up the heat in the Cuatrociénegas basin. It won’t be long before it’s over 100 degrees,
and the endangered Coahuilan aquatic box turtle is digging itself into the sand and mud to avoid the heat.
“They'll seek out burrows or grass clumps to stay cool during the day...but I'm sure we'll find some," says Hendrickson.
That’s Dean Hendrickson, a biologist with the University of Texas at Austin who’s been studying the turtles since 2002 and coming to Cuatrociénegas since 1979.
The Coahuilan box turtle is the only known aquatic box turtle in the world, and they live in this unique valley in Mexico
dotted with geothermal springs, rivers, wetlands,
and over 70 endemic species.
Even on this dry, hot day, the turtles use rivulets of water like highways to get to shadier, cooler places.
“They spend on an average day probably 90 percent of their time in the water.
Algae grows on their shells. They're really aquatic turtles. There's no doubt about it.
They do get out and move around some, but most of their life they are in the water,” says Hendrickson.
Hendrickson and his team have been monitoring the turtles for about 6 years. In 2002, graduate student Jennifer Howeth began a mark and recapture program.
“…that way we can capture individuals multiple times over long periods of time, measure them, weigh them, track their condition, their growth rates
and start to get a handle on population sizes and mortality rates. And movements," says Hendrickson.
Hendrickson and Howeth estimate that there are about 2000 of these turtles on the planet. The Coahuilan box turtle is considered one of the 25 most endangered turtles in the world.
“This is a CITES listed critter. It's got all the protection it could possibly get,” Hendrickson says.
But Hendrickson says there are few resources available to enforce the laws. The turtles are in the pet trade and fetch a pretty high price. And they are further threatened by drying and contraction of their precious wetlands.
Irrigation for agriculture, climate change and invasive species pose the greatest threats. Hendrickson says, “There are records of these things from all along the edges of the mountain, lots of areas where there’s now no water at all.”
“Remember when I said it was way high up there? So clearly that flow is going around this thing now whereas it used to come through here and there was a series of isolated pozas up there.
Its always been obvious that this is a very dynamic area but… I’ve never seen it this dry before. It's really pretty remarkable.”
Meanwhile, the turtles forge on and the monitoring program continues. “We really don’t know too much about how they move and little about their reproduction," says Hendrickson. "There’s lots of basic biology that needs to be learned before we can really manage these things.”
"This would be number 4000...4, 1, 7, 3. So I got that number by reading these codes and their placement on the scutes around the shell."
The University of Texas at Austin