Habitats: Sanddunes – Photo Essay
Sanddune Lizards
On May 4th, 2007, Dr. Allan J. Landwer of the Hardin-Simmons University in Abilene, Texas joined David and Kay Crum of the June Leland Wildlife Foundation and Burr Williams, Executive Director of the Sibley Nature Center on a ranch in northern Yoakum County, Texas. The university was recently the recipient of a bequest from one of the heirs of the ranch and is now a minority owner.
The June Leland Wildlife Foundation has leased the ranch for the past 6 years for lesser prairie chicken preservation. They won the 2004 Texas Parks and Wildlife Departments Texas Land Steward Award, and have worked in partnership with the Texas Parks and Wildlife Department, the U.S. Fish and Wildlife Service, the Playa Lakes Joint Venture, and provided a research site for students from Texas Tech, and Texas A&M.
Dr. Lanwer specializes in lizards. In the 1990s he participated in studies of the sand dune lizard in Chaves County, New Mexico. The lizard was once considered a subspecies of the sagebrush lizard of Nevada, but recently became considered a stand alone species. Mr. Crum had seen what he believed to be the sand dune lizard, but wanted verification from one of the leading authorities of the species. The group toured the ranch for 4 hours during the afternoon.
“The sand dune lizard is endemic to a small area of shinnery oak habitat in parts of southeast New Mexico and adjacent Texas. In New Mexico, the species is known to exist as fragmented populations within an area of ca. 2,312 sq. km (892.6 sq. mi) in parts of Chaves, Eddy, Lee, and Roosevelt counties. However, within this area the potential and occupied habitat consists of only 1,697.3 sq. km (655.3 sq. mi). Total extent of the range in Texas is unknown although it includes parts of Andrews, Crane, Gaines, Ward, and Winkler counties. In New Mexico large populations of the sand dune lizard occur on lands managed by the U.S. Department of Interior, Bureau of Land Management, (BLM) although important populations occur on New Mexico state and private lands as well.”
“Historic population sizes of S. arenicolus are unknown, although the chemical treatment and removal of shinnery oak and oil and gas extraction activities has caused the decrease or extirpation of some populations since the species was discovered in southeast New Mexico in 1960. Large-scale habitat destruction is the major threat to the continued existence of S. arenicolus in southeastern New Mexico. Of the major land use practices that occur within the range of S. arenicolus in New Mexico, it has been established through previous studies and observations that the widespread use of herbicide for shinnery oak control and activities associated with oil/gas extraction have the greatest potential to cause significant sand dune lizard population extinction or reduction. The short-term trend of these activities is population decline; the long-term trend is unknown but increased habitat fragmentation results in increased probability of extinction of individual populations. Other activities with the potential for habitat destruction (i.e., ORV use, livestock grazing, and fire) have been little studied or are considered of lesser importance in the conservation and management of sand dune lizard populations.” (Introduction to the New Mexico Game and Fish Departments’ Recommendations for sand dune lizard conservation.)
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Dr. Allan Landwer in a blowout, the only habitat of the sand dune lizard.
Dr. Landwer and David Crum surveying a dune field for blowouts.
The grazing lessee of the ranch with a herd of 60 cattle gathered up to be moved to another pasture. The cattle are being moved to give peace and quiet to nesting lesser prairie chickens.
Most of the dunes are vegetated with shinoak (Quercus havardii). The shinoak is denser in the Texas sand dune fields than in the New Mexico dune fields. Will the denser cover preclude the presence of the sand dune lizard?
Four wheel drive vehicles can go almost anywhere on vegetated dunes. As long as the same path is not taken repeatedly, little permanent damage occurs to the vegetation. Repeated traveling on one path will create a compacted road that will begin to erode from both wind and water.
Yucca campestris is common in the dunes. Some individual plants display characteristics of hybridization with Yucca angustifolia. These individuals' bloom stalks have less branching and the bloom panicle starts within the leaves, instead of above, as in pure campestris. Cattle, feral hogs, and mule deer often eat the bloom shoots.
Within the vegetated dunes there are often mottes of taller shinoak. Williams wondered if the Hardin-Simmons botany professor would find interest in examining the genetics of the two forms - no one knows why the mottes form. In the foreground is last year's whitish sand bluestem grass stalks and the gray fronds of the shrubby sand sage.
In another motte the nest of either a greathorned owl, Chihuahuan raven, or a Swainson's Hawk awaits this year's resident.
Penstemon buckleyi is endemic to the region's dunes, but occurs infrequently. Some of the plants will reach 4 feet in height, although most are less than 3 feet. The late Barton Warnock of Sul Ross considered it an annual species, but Williams is not so sure (sometimes clumps can be found with 5 or more bloom stalks.)
In much of the region's dune fields Senecio spartioides v. Fremontii is common, but on this ranch only Senecio longilobus was found during the day's visit.
Stillingia sylvatica (Queen's delight), a member of the Euphorbia family, is another indicator plant of the sand dune region. Indians and early Spanish and Anglo settlers have used the roots medicinally as both a skin salve and as an emetic.
Cryptantha crassisepala is another plant that prefers the looser sands of the region.
C. crassisepala and Spectacle Pod Dimorphocarpa wislizenii can turn sandy areas with almost no shin oak into glorious fields of white in May.
Calylophus serrulatus is another species that prefers the sand dune habitat. This member of the Evening Primrose family will sometimes reach a height of three feet, but is usually a mound less than a foot tall. West Texans call the species sundrops or buttercups.
As a person looks out over the dune field, several blowouts can be spotted. Mr. Crum indicated that these particular blowouts had contained Indian artifacts on his previous visits.
Some clumps of shinoak were not completely leafed out. All of the area not leafed out is likely to be one clone (one individual plant). 90 percent of the shin oak was leafed out, although a month earlier all of the oaks had been freeze scorched during the regular leaf-out period of early April.
In this blowout a sand sage has had almost two feet of root exposed. Note the darker colored soil indicating high levels of moisture from the rain two days before. If a person dug there and then left the pit open overnight, there is a good chance a pool of water would have formed.
To get to the blowouts, a person has to push through the shinoak forest, and when a person can not see their feet in rattlesnake country, the experience can be nerve wracking for those faint of heart.
On the floor of a blowout litter often collects from the surrounding shin oak forest. Sand dune lizards freeze when they feel in danger, but if a person gets too close, they skitter away rapidly to freeze again. Dr. Landwer will hopefully put out hundreds of buckets (their tops level with the sand and covered over with plywood) and pit-trap the ranch in the future to determine the extent of the possible population of the lizard.
Lizard burrows were plentiful along the edge of the blowouts. The burrows were usually under a shin oak where its roots tightly hold the sand together. Most burrows were within 2 feet of the edge of the blowout. Three side blotched lizards were spotted during the hour-long hike in this area, so seeing the burrows was not proof of the sand dune lizard. A Six-lined racerunner lizard was also seen along a gravel road later.
In some of the blowouts, one of the species of bluestem grass was just beginning to grow.
A young sand sage, more bluestem, and a shin oak leaf were in the bottom of this blowout.
In another blowout, Mr. Crum pointed out an Indian artifact - chipped flint, but none of the group knew exactly what type of point it was, if it was a point.
The photographer failed to take several pictures of this mano that a feral hog had dislodged from a sheer face of a northfacing wall of a blowout, so the "sand glare" is overpowering. Colonel John Shafter's men in 1871 suffered from "sand blindness" and had to make sunglasses out of bandanas.
The artifacts were in an area with harder soils at the bottom. Very ancient mesquite roots were also found in the same blowouts. No living mesquites were within a half-mile. Had these hunks of wood been waiting here with the artifacts for 500 or more years? Had mesquite grown where the blowouts are now? Questions for thorough scientific inquiry abound in the sand dune region!
Prickly pear normally can not grow in areas of moving sand. Ragweed is in the top left.
As the group returned to the vehicles, Dr. Landwer and the Crums spotted a "white blur," that Dr. Landwer stated "had the jizz" of a sand dune lizard. The sideblotched lizards move differently and are "tannish-gray blurs." Hopefully on another expedition, the presence of the rare lizard can be verified without a doubt.