After the first two days at Big Bend National Park had us baking under abundant sunshine and highs around 86 degrees F (30 C), day three found my wife and I under very different conditions. We set out north from the Chisos Basin at 6 AM with a temperature of only 22 F (-6 C) and thick fog. Knowing the area was crawling with deer, bears, and mountain lions, we took it easy coming down out of the mountains.
As we reached the flats north of Panther Junction it was still only 30 F (-1 C) and the sky was filled with dense clouds. Deserts are fickle environments and wild swings in the weather are not uncommon, especially in winter.
Undaunted by the cold, gloomy conditions we continued northward to drive the length of the Dagger Flat Auto Trail. This gravel road heads off the main road for seven miles toward the Sierra del Caballo Muerto (Dead Horse Mountains). The road ends at Dagger Flat, a unique location that harbors a forest of giant dagger yuccas (Yucca carnerosana or Y. faxoniona, Asparagaceae).
These yuccas can reach tree-like heights of 30 feet (9 m) with diameters up to two feet (61 cm). In late spring they send up spikes of cream-colored flowers, and each inflorescence can weight nearly 70 pounds (32 kg).
Giant dagger yuccas are relatively rare plants since they are particular to limestone soil. Dagger Flat is an ideal home for these plants because it is surrounded by outcrops of Buda Limestone. These sedimentary layers were deposited by the shells of dead marine organisms in a reef that existed here around 95 million years ago (Cretaceous Period). Later geologic activity uplifted and eroded this limestone, creating the soil that giant dagger yuccas love.
The Dagger Flat Auto Trail features a number of other yuccas as well, including Thompson’s yucca (Yucca thomsoniana, Asparagaceae):
A variety of other plants can also be found along this stretch of road. One of particular note is lechuguilla (Agave lechuguilla, Asparagaceae). Lechuguilla is an indicator species for the Chihuahuan Desert. This means these plants occur naturally only in this desert. Similarly, saguaro cacti are indicators for the Sonoran Desert and Joshua trees are indicators for the Mojave Desert.
This area of Big Bend is more than just plants, however. As we continued north to the exit at Persimmon Gap, we encountered two bobcats (Carnivora: Felidae: Felis rufus) that were sitting near the road. Although the early-morning light was low and the cats were quick, I managed to get this blurry shot of one of them:
We hung around for a minute to watch these predators and before long they ran off into the dark foliage. A few seconds later a mountain lion (Carnivora: Felidae: Felis concolor) ran across the road in the same direction, apparently chasing the smaller cats. Since we only got a glimpse of it I couldn’t get a shot. I would have to settle for a photo I had taken earlier of a mounted specimen in the Chisos Basin visitor center:
Although day three was rather gloomy and cold, these wild cats ended our trip to Big Bend on a high note. We only got to spend three days in this massive national park but it provided a variety of memorable experiences. Boquillas, Mexico, the Chisos Basin, the Ross Maxwell Scenic Drive, and Old Maverick Road offered up wildlife, plants, geology, culture, solitude, and beautiful scenery that easily earned this park a “Top Ten” place my personal national park rankings.