Not Exactly a Day at the Beach
Although plants in this region must endure minimum shade and shelter, along with much heat and dryness, shifting sand, and few soil nutrients, 62 species at least have still managed to adapt. Water arrives during violent events, with more than half of the annual seven to eight inches falling during the thunderstorm months of July, August, and September. The water penetrates the sand rapidly, but due to capillary action, it sinks to a certain level and no lower. Blue-green algae may flourish after a rain and give a slight tint to the dunes.
The cleverest adaptations come in the form of elongated stems on skunkbush, sumacs, and soaptree yuccas. The sand-stabilizing roots of rubber rabbitbrush, the stunted Rio Grande cottonwood trees, and the low-growing rosemary mint also represent an elegant compromise of organism with environment.
It is easy to spot the yuccas, which have clusters of large, cream-colored blossoms in early summer, and to observe their growth (as much as 30 feet high) in response to the advancing sand. The pollination of the yucca by the pronuba moth provides a wonderful demonstration of interdependence. As part of a symbiotic exchange, the moth larvae feed on the seeds of the yucca plant. Also residing here are delicate Indian ricegrassthe best protein source for animals in the dunesand jointfir, better known as ephedra or Mormon tea.
Look for short-lived pedestals of gypsum hardened by rain. These are held together by the roots of skunkbush, cottonwood, or yucca plants. After these plants elongated, the sand moved on and left these pedestals behind.
More than 90 percent of the animal species inhabiting the monument area are birds and insects. Most intriguing is the darkling beetle, with its distinctive tracks that run all over the dunes. Rarely seen in the daytime are the bannertail kangaroo rats, snakes (which hibernate in winter), and the toads and rodents that estivate underground during summer hot spells. Though rarely seen, the western hognose snake, which has a snout for digging out dormant desert toads, lives here. More easily spotted are the swift insect-eating lizards that scoot about the dunes seeking shade during the day. Burrowing is a common practice used to escape the heat of day and the cold of the desert night.
The most frequently seen mammal is the kit fox, but coyotes, badgers, porcupines, rabbits, and skunk hunt in the fringe areas around the dunes. The three poisonous species of reptiles and amphibians native to the regionthe rare desert massasaugua, as well as the diamondback and prairie rattlesnakesare scarce and live primarily outside the dune area.
The birds are keenly aware of snakes, lizards, rabbits, and insects, because these are excellent food sources. Predator birds include the great horned owl, Swainson's hawk, roadrunner, loggerhead shrike, nighthawk, western kingbird, and flycatcher. Patient birders can also spot the golden eagle, sparrow, oriole, mockingbird, and meadowlark.
An interesting camouflage adaptation is manifest in the white dunes habitat. To escape predators, natural selection favors animals that are difficult to see. Two lizard species and some mice are almost pure white. Many other animals are lighter in color than expected: one type of cricket, for example, is nearly transparent.
© Article copyright Fulcrum Books. All rights reserved.
Details mentioned in this article were accurate at the time of publication