Mountain lions, black bears, bighorn sheep, working cowboys – the list of charismatic West Texas creatures is long. For reptile lovers, that list certainly includes the western hognose snake. It’s a popular pet across the U.S., and is bred extensively in captivity. Ease of handling is part of the appeal, but it’s the snake’s strange, shovel-like face that’s the real clincher. The hognose also has a host of fascinating behaviors. Its reclusiveness only adds to its charisma.
Now, scientists have conducted new research on the hognose. They’ve solved basic mysteries about the creature. They’ve also revealed its epic evolutionary journey.
Dr. Corey Roelke is a herpetologist at UT-Arlington.
“Hognose snakes are very difficult to find,” he said. “They spend a majority of their lives underground. And you can go years without seeing them if conditions aren't right.”
Roelke recently led an ambitious genetic study of the hognose.
The snakes, he said, eat lizards and rodents. But amphibians are their speciality. After monsoon rains, they emerge from subterranean lairs to hunt their favored prey.
They then risk becoming prey themselves, and they’ve evolved multiple lines of defense. Mature males are typically a foot long, females about 2 feet. Their coloration – brown, with darker patterning – resembles that of massasauga and prairie rattlesnakes. If that doesn’t dissuade a would-be predator, a hognose makes itself “big and scary,” Roelke said, by hissing and swelling its neck.
And if that fails, the dramatics ensue. In an elaborate “death-feigning” performance, the hognose rolls and flips, finally coming to rest on its back, and emitting a foul odor. This can convince a coyote or bobcat it’s dealing with a “gross, dead animal,” Roelke said, that’s not worth eating.
The hognose also moves very slowly. That’s effective defense against raptors, which rely on motion to detect prey. But it’s not so adaptive for modern roadways.
“If you take 15 minutes to cross a 30-foot section of road,” Roelke said, “that saves you from the hawk, but it doesn't save you from the truck.”
There are multiple hognose species. There’s the southern hognose in the Deep South. The eastern hognose is found as far west as the Texas Hill Country. Then there are hognose snakes that thrive in prairies, from the desert grasslands of northern Mexico up the Great Plains to Canada.
The hognose snakes found in Mexico and Trans-Pecos and South Texas look different from those found in more northerly prairies, and in the 1990s, scientists concluded they were two species – the Mexican hognose and the western hognose. But Roelke and his colleagues had their doubts.
“And we wanted to know, are there really two species of western hognose?” Roelke said. “And we applied genetics to it. We were the first people to do that. And we have an answer.”
They conducted DNA analysis for 250 snakes. The results proved that the Mexican and western varieties are in fact a single species.
The scientists have an explanation for the differing appearances. Seventeen thousands years ago, during what’s called the “last glacial maximum,” ice sheets stretched down the Great Plains. In those cold conditions, many creatures only survived in isolated pockets.
Roelke suspects one hognose population found refuge somewhere in the north, while most endured in present-day Mexico. When the Ice Age ended, those populations began to spread out. While they looked distinct, they were still a single species.
Now, they’re meeting up. Hognose snakes with intermediate characteristics are found hear near the Pecos River, testifying to the reunion of the two groups.
Grasslands are among the continent’s most imperiled ecosystems, and their decline bodes ill for the western hognose. But these creatures are survivors. For now, they endure – another member of our region’s remarkable fauna.
