Big Bend National Park Wildlife: Animals You’ll Spot, Including Venomous Species, in Incredibly Diverse Park

by Jon D. B.

Prep for your Big Bend National Park wildlife watching with Outsider’s guide to the key animal species of this tremendous ecosystem.

You’ll be hard-pressed to find a more ecologically diverse park than Big Bend. Here, everything from bighorn sheep and black bears to 31 species of snakes roam the far western reaches of Texas, and it all comes down to the landscape’s wildly varied habitats.

Incredibly, Big Bend has more species of birds, bats, butterflies, and scorpions than any other national park in America. In total, 11 species of amphibians, 40 species of fish, 56 species of reptiles, 75 species of mammals, and 450 species of birds call Big Bend National Park home. And that’s to say nothing of the 3,600+ insect species buzzing around the park.

Below, you’ll find highlights of some of the species you’re most likely to encounter while visiting the park, alongside:

  • Charismatic mammals of Big Bend National Park
  • Lesser-seen predators of Big Bend
  • Birding Hotspots of Big Bend
  • Venomous Snake identification

And remember, in Big Bend National Park, smaller wildlife can pose as big a safety concern as megafauna. Venomous snakes, scorpions, spiders, and centipedes are all active during warmer months. Pay attention to where you walk and place your hands. Consider wearing high boots or protective leggings while hiking. If you’re camping, be sure to inspect all shoes, sleeping bags and bedding before use, and always carry a flashlight at night.

Bighorn Sheep Battle Invasive Barbary Sheep for Resources in Big Bend

Once plentiful in the area, Desert bighorn sheep were long gone prior to Big Bend National Park’s establishment in 1944. In recent years, Texas Parks and Wildlife Department has reintroduced the species to the Black Gap Wildlife Management Area. Today, a “small but persistent” population resides to the north and east of the park in the Deadhorse Mountains area.

You may, however, spot an imposter while wildlife watching in Big Bend National Park. Barbary sheep, or aoudad, now inhabit the park. Originally native to North Africa and the deserts of the Middle East and Asia, aoudad were first kept on private game ranches in Texas. But their release, whether accidental or compulsory, led to reproduction and expansion. They now inhabit the breadth of Big Bend National Park, and have likely been present since the 1970’s.

Aoudad remain, however, a harmful invasive species. They compete with native desert bighorn sheep for resources such as territory and grazing, chiefly. This threatens the native’s bighorn’s restoration considerably.

To tell the species apart, look for the signature white rump and muzzle of the desert bighorn sheep, both of which the barbary sheep lack.

Big Bend National Park’s Most Iconic Wildlife: The Javelina, or Peccary

Collared Peccary or Javelina is widespread through the Southwestern United States and Central and South America. It is not a member of the pig family, despite its looks. (Photo by: Jon G. Fuller/VW PICS/Universal Images Group via Getty Images)

Is that a pig? It sure isn’t! Big Bend National Park is home to a menagerie of remarkable wildlife, but it’s the javelina that often captures the imagination of visitors. Javelina, or collared peccary, are found all the way south to Argentina. But it’s Big Bend that makes up the northernmost tip of their range – which is is exactly why these curious mammals are a stranger to the majority of America.

Javelina stand apart from pigs in quite a few ways. For one, they only have 3 toes on their back feet, as opposed to a pig’s 4. The bones in their feet and lower arms are also fused unlike a pigs. They also have scent glands and a complex stomach, but lack the sweat glands and gall bladder of a pig.

Anatomy aside, Javelina are often found traveling in groups of anywhere from 2 to 22 animals. They’re a common and charismatic sight across the park.

The ‘Remarkable, Natural’ Black Bear Resurgence of Big Bend

North American black bear. (Photo by: Peter Zenkl/VWPics/Universal Images Group via Getty Images)

If you’re a fan of national parks, then it may feel as if the North American black bear is everywhere. This is, of course, not true, but this highly adaptive species is now found across America in more states than not. And Big Bend National Park is home to a remarkable feat of nature, as black bears have returned to this historic habitat all on their own.

Yet this comes after a long and spotted history in Texas. Back in the early 1900s, bears were common in the Chisos Mountains in Big Bend country. But by Big Bend National Park’s establishment in 1944, there were virtually no bears left. The park cites shooting and trapping by ranchers, federal predator control agents, recreational hunters, and loss of habitat as all contributing greatly to their decline.

As nature sometimes does, however, an inexplicable resurgence would occur in the late 1980s. Visitors began seeing bears in increasing numbers, and today, several dozen black bears call the Chisos Mountains home.

Safety remains paramount with black bear sightings, however. For more on crucial black bear safety, see our Big Bend National Park Safety: Crucial Tips for a Safe, Successful Big Bend Adventure next.

Badgers Burrow Throughout Big Bend National Park

American badger. (Photo by DeAgostini/Getty Images)

One of the park’s most unique mammals, badgers make ready homes of Big Bend’s open grasslands. There, they hunt mostly mice, squirrels and groundhogs. These solitary hunters are experts at digging prey out of their burrows. This has led to a common misconception that coyotes and badgers hunt together. The reality, however, is that opportunistic coyotes will wait near a foraging badger in an attempt to steal prey.

In remote areas with no little human encroachment, the typically nocturnal species can be routinely observed foraging during daytime in Big Bend.

Big Bend National Park Wildlife: Other Predators You May Spot

Large carnivores like coyotes and cougars are ever present in Big Bend. As keystone species, bot provide crucial population control of prey, such as rodents for the coyote, and grazing deer for the cougar. Though incredibly rare, cougars are known to source humans as prey.

Mid-sized carnivores are well-represented in Big Bend, too. Smaller than their canine coyote kin, the gray fox is much more elusive and hard to spot. The same can be said of the feline bobcat, which is typically a fifth of the size of a cougar.

Learn more about crucial cougar safety from Big Bend National Park’s wildlife team here.

There Are More Bat Species in Big Bend Than Any Other Mammal

A Long-eared Bat. (Photo by: Jaanus JŠrva/Focus/Universal Images Group via Getty Images)

Incredibly, bats make up the largest portion of the park’s mammal species by far. 20 species of bats call Big Bend National Park home. This includes the endangered Mexican long-nosed bat, found nowhere else in the United States, the park cites.

Mexican long-nosed bats (Leptonycteris nivalis) are limited a single colony that resides in the Chisos Mountains within the US. These adorable little mammals feed on flower pollen and nectar. And come the blooming of specific plants like the century plant (Agave havardiana), their incredible migration south into Latin America begins.

19 other bat species are far more plentiful in the park, however. Keep your eyes peeled as night approaches and they take to the skies.

Birding in Big Bend National Park

Big Bend is one of the best national parks to bird in North America. Here, you can observe a wide variety of bird life in incredibly diverse habitats.

The following locations are birding hotspots in Big Bend National Park:

  • Rio Grande Village: 305 species, such as green herons, green kingfishers, northern cardinals, sora, golden-fronted woodpeckers, common black-hawks
  • Chisos Mountains: 312 species, such as acorn woodpecker, Colima warbler, Scott’s oriole, black-crested titmouse, Mexican jay, northern flicker
  • Cottonwood Campground: 248 species, such as great horned owl, black phoebe, black vulture, vermilion flycatcher, yellow-rumped warbler, ladder-backed woodpecker
  • Dugout Wells: 195 species, including greater roadrunner, Inca dove, ash-throated flycatcher, summer tanager, phainopepla
  • Sam Nail Ranch: 188 species, including painted buntings, scaled quail, green-tailed towhee, yellow-breasted chat, pyrrhuloxia
  • Blue Creek: 135 species, such as black throated sparrow, Lucifer hummingbird, mourning dove, cactus wren, blue grosbeak, canyon towhee

While many of these sites hold an impressive 100-300 species sightings, over 450 bird species have been documented in the park in total.

Snakes are Protected Wildlife in Big Bend National Park

22 species of lizards and 6 species of turtles roam Big Bend. But the 31 species of snakes in the park easily take the reptile crown.

In total, 4 species of rattlesnakes and the Trans-Pecos Copperhead all call Big Bend home. Learn to identify each below.

Western Diamondback Rattlesnake (Crotalus atrox)

The Western Diamondback Rattlesnake or Texas Diamondback is a venomous snake found in the southwestern U.S. and northern Mexico. (Photo by: Jon G. Fuller/VWPics/Universal Images Group via Getty Images)

The venomous western diamondback rattlesnake is found across a wide range of Big Bend National Park. From the Rio Grande floodplain up to the foothills of the Chisos Mountains (up to about 4,500 feet), visitors should be wary of its presence.

“Western diamondback rattlesnakes are aggressive and easily excitable, and cause more fatalities than any other snake in the United States,” Big Bend National Park wildlife officials cite. Identify this species by their plump body, short tail, broad triangular head, and black-outlined diamond pattern (above).

Otherwise, rattlesnakes are good at controlling rodent problems, and also eat small mammals, birds, fish, and invertebrates.

Mojave Rattlesnake (Crotalus scutulatus scutulatus)

Mojave rattlesnake in the High Desert. (Photo by George Wilhelm/Los Angeles Times via Getty Images)

Mojave rattlesnakes are also found throughout the park. Visitors to the Rio Grande floodplain should be especially cautious.

Similar in appearance to the western diamondback, this rattlesnake species prefers low, hot deserts, creosote bush flats, as well as grasslands. But the key difference in identification is the banding on the Mojave’s tail. On a Mojave, these bands are mostly white with thin black bands. On a western diamondback, however, the black and white bands appear similar in size.

Black-tailed Rattlesnake (Crotalus molossus molossus)

Northern black-tailed rattlesnake / black tailed rattlesnake / green rattler (Crotalus molossus) resting curled up under rock, venomous pit viper native southwestern United States and Mexico. (Photo by: Arterra/Universal Images Group via Getty Images)

The striking black-tailed rattlesnake prefers the mountains, canyons, and rock outcrops of Big Bend. Found park-wide, black-tails are most common in the Chisos Mountains and foothills. Black-tails can and will climb trees, and can also swim rapidly.

Interestingly, black-tails will use three defensive mechanisms to alert foes. They will first rattle their tail to startle an aggressor. Then, they will then hiss loudly and rapidly flick their tongue, in addition to rattling. If these tactics don’t work, black-tails will puff up and coil their bodies, making them look much larger, as do many species of vipers.

Mottled Rock Rattlesnake (Crotalus lepidus lepidus)

Mottled rock rattlesnake (Crotalus lepidus lepidus) native to southwestern United States and northern central Mexico. (Photo by: Arterra/Universal Images Group via Getty Images)

The fourth venomous rattlesnake species in Big Bend National Park’s wildlife is the Mottled Rock Rattlesnake. Found throughout the park, they are also most common in the Chisos Mountains and foothills. This species spends most of their lives in rocky outcroppings and talus slopes.

Importantly, mottled rock rattlesnakes are small compared to other rattlesnakes species. They will rarely exceed 3-feet in length, but retain the thick body shape characteristic of rattlesnakes.

Thankfully, these rattlesnakes are not aggressive by nature. Instead, they rely on camouflage to avoid detection.

Trans-Pecos Copperhead (Agkistrodon contortrix pictagaster)

A snake composed of alternating bands of white and rusty red lies comfortably in the grass.
NPS/J. Jurado

The venom of the Trans-Pecos copperhead is less potent than the rattlesnakes of Big Bend. This species is found throughout the park in proper habitat, which includes springs and the Rio Grande. If threatened, copperheads can vibrate the tip of their tail to mimic a rattlesnake.

Always watch your step and where you’re heading. They will strike if sufficiently threatened.

To view the rest of Big Bend National Park’s snakes, see the park’s wildlife glossary here.

And for more information on Big Bend safety, see our Big Bend National Park Safety: Crucial Tips for a Safe, Successful Big Bend Adventure next.

*Bonus: Believe It Or Not, Elk Roam Big Bend National Park, Too

North American elk, or wapiti. (Photo By Lyn Alweis/The Denver Post via Getty Images)

According to the park, a breeding population of elk have been in the northern grasslands of the park since the 1990s. Today, the elk population in the park is between 30-40. Visitors will sometimes see elk, or wapiti, as far south as Tornillo Flats and Tornillo Creek.

Happy trails towards Texas’ end of the road, Outsiders!