Today I hiked through the Sabal Palm Sanctuary, a 557-acre preserve along the Rio Grande, about as far south in Texas as it is possible to go. It is known for birding, butterflies, and among herpers, its claim to fame is the presence of such species as Texas indigo snakes, black-striped snakes, and speckled racers. The Master of Ceremonies, however, is the sabal palm or sabal palmetto, a palm tree that can reach over 60 feet in height and has a crown of fan-shaped leaves. While sabal palms used to grow in groves along a considerable portion of the lower Rio Grande valley, these wild-growing groves or forests of palms have mostly disappeared. The trunks of these palm trees often have a cross-hatched, latticework appearance because when it loses leaves, the bases of the leaves often remain in a sort of upside-down “Y” known as a “bootjack.” The diagonal portions of the “Y” are overlapped by newer bootjacks, leading to the distinctive appearance. On the other hand, if these bootjacks are removed or lost, the trunk has a fairly smooth appearance.
We drove down Las Palmas Road, and over a levee and through a gap in the enormous border fence, while a Border Patrol vehicle looked on. The first person we spoke with at the sanctuary said they really have no comment about the border wall, because of the controversy. A different person we spoke to before leaving said that he understood no further wall was planned at this location, other than the existing “fence” of 18-foot reddish-brown upright steel bars.
When we arrived, of course Clint contrived to get the very first sighting, suitable for posting to iNaturalist: it was a Mediterranean gecko, and a dead one at that, lying on the sidewalk into the visitors center. Some people will do anything for an added sighting at iNat!
We started our walk through some open woodland and checked out the overlook to the Rio Grande, and then headed for the butterfly garden. Along the way, Clint found several noteworthy invertebrates – one was an ant mimic, apparently a type of assassin bug that looks at first glance like an ant. We began seeing large numbers of what appeared to be the milkweed tussock moth caterpillar, a hairy beast with tufts of black and white with a few spots of orange, advertising to any and all birds that it is too toxic to eat.
An additional caterpillar was a little black-and-white banded critter with yellow projections or knobs around it. This was the larval form of Forbes’ silkmoth, a very uncommon species. The adult winged form is huge and decorated with bands of reddish brown and yellow, with four translucent teardrop-shaped spots that give it the name “cuatro espejos” (four mirrors) in Mexico.
We then entered the Forest Trail, winding through a more closed canopy of sabal palms and other trees. At 11:32am, a fair distance in, the temperature was 77 degrees with a comfortable relative humidity of 49%, with breezes sighing overhead. The forest here is like the Rio Grande Valley’s version of the Big Thicket: dense, biodiverse, and looking like it had been undisturbed since before Texas was settled. Palms were mixed with acacias, ebony blackbead trees, and the understory a profusion of vines. Without enough sunlight for grass, the ground was covered in such things as palm fronds, seed pods from the ebony trees, and downed palm trunks here and there, growing moss. It was like sitting on a bench in a prehistoric forest.
The trail took us on a short boardwalk over a low place and further along through this semi-tropical wonderland. In a couple of places, an odd cactus grew in the dappled light, with long strongly-ribbed stems that lean this way and that, with tufts of spines along each rib. It is called barbed-wire cactus or triangle cactus (presumably because of the shape, in cross section, of the stems). It is said to be night-blooming in the summer, with big white blooms that attract hummingbird moths.
By this time we had gone down separate paths, as Clint and I often do on these trips. I went past fragrant thickets of some bush with small white flowers, with clumps and patches of Turk’s cap scattered through it. The hum of the bees and the fragrance of the flowers was hypnotic, and tiger swallowtail and sulphur butterflies danced among the flowers. The trail led back up and into the forest.
By this time I wondered if Clint was anywhere near, and I called him. He said he was near the blind, an elevated structure extending partly over the resaca where birders can watch different species without spooking them. He said he had seen an indigo snake, and so I set out to join him. When I arrived, he said it was gone; it had been cruising through some cut brush near the water and had then made its way up and disappeared within the layers of vines, palm fronds, and other vegetation. That was a disappointment, as the Texas indigo snake is such a great find that even a short glimpse of this large, glossy serpent is a big deal.
Down a path into a particularly lush part of this jungle/forest, I sat on a bench for a while looking at the magnificence of the place. Something grew in every available inch of space; vines threaded their way up the latticework of palm trunks, and on the ground under the carpet of living plants must be a complex layer of decaying palm fronds, fallen branches, and fungi, returning previous years’ plants to the soil. How many frogs must by hidden in all this complexity? What lizards prowl through the leaf litter? There are certainly worlds within worlds in this place, from the birds in the canopy to the communities of invertebrates and their predators in the branches, to the various things below that living carpet of plants, the scavenging, root-munching, soil digesting invertebrates and the insects, reptiles, and amphibians that search them out and eat them. We could study these communities of life for years and still have more to learn.
And then it was time to visit more worlds. We walked along a boardwalk over a part of the resaca (which is a body of water that started out as a bend in a river but then got cut off and isolated, but can be recharged during floods or by rainfall). Further along the trail, at the edge of a small pond, we saw a white peacock butterfly, which was an unusual enough find to catch Clint’s attention. The upper wings are pale, with beige and light brown markings that has been suggested to resemble antique lace. According to the Butterflies and Moths of North America website, it is found in south Texas and down through Central America, and its habitat is “open, moist areas such as edges of ponds and streams” – a perfect description for where we found this one.
One last interesting find waited for us on the way out. We had seen Texas spiny lizards, green anoles, and whiptail lizards, and now we would see a pretty invasive, the brown anole. This anole is native to Cuba and the Bahamas, and has been introduced to parts of the southern U.S. where it aggressively out-competes our native green anoles. This is a sad state of affairs, but one that we could not correct with this little lizard, busily climbing a piece of rebar in a small butterfly garden near the visitor’s center. So, we admired him and let him go on his way, hunting for insects for a late lunch.