White on White - An invertebrate inventory of White Sands National Monument

The largest gypsum dune field on Earth—covering 275 square miles—undulates across the Tularosa Basin in south central New Mexico. Approximately 40 percent of the field falls within the protected area of the White Sands National Monument in Otero County. The unusual feature started forming about 8,000 years ago, when water evaporated from the surface of large lakes near the southwestern boundary of the current dune field, and gypsum crystallized out of solution. Over time, weathering degraded the crystals to sand-size particles, and winds, predominately from the southwest, blew the gypsum sand from the now-dry lake bed onto the dune field, which can rise as high as sixty feet. The blowing sand moves the dune crests from the southwest to the northeast as much as twenty-nine feet per year, covering and uncovering plants and soils as they move. Plants respond to the harsh conditions of shifting pure gypsum soils in several ways. They add stem length rapidly to accommodate encroaching dunes; they send out rhizomes (lateral roots) so new shoots can sprout up sixty feet away from the original plant; and they further bolster their root systems to avoid being taken over by a passing dune. Many animals have adapted to life in the white dunes by evolving modified coloration. Such White Sands species and subspecies as the southwestern fence lizard (Sceloporus cowlesi) and the endemic bleached earless lizard (Holbrookia maculata ruthveni) are paler than closely related populations that live outside the gypsum dunes. Animals that are naturally white or pale in color elsewhere may reside at White Sands to take advantage of the pale substrate. A lycosid, or wolf, spider maintains production of its natural darker pigments, but secretes a waxy substance to appear white. Before 2006, almost nothing was known about the invertebrate fauna in White Sands, or in Carlsbad Caverns National Park, another protected area of the northern Chihuahuan Desert about 190 miles from White Sands. As a result, the United States National Park Service invited me to conduct a ten-year study of the lepidoptera in the dunes of the Monument and within Carlsbad Caverns National Park. A primary purpose of the study was to survey the moths in various habitats within Carlsbad and White Sands, and to describe new species discovered during the study. Since the study began, in January 2007, we have recorded more than 600 species of moths, including 26 species new to science...more