White Sands

by Joseph DeSisto

During my trip to the Southwest I had the chance to spend a day at White Sands National Monument, one of the most ecologically bizarre places in North America. White Sands is located in the dry lowlands of Tularosa Basin, in southern New Mexico. Due to a geological oddity, the sand here is made up of sparkling white gypsum crystals.

White dunes of gypsum sand at White Sands National Memorial. Photo by Jennifer Wilbur, licensed under CC BY-SA 3.0.

White dunes of gypsum sand at White Sands National Memorial. Photo by Jennifer Wilbur, licensed under CC BY-SA 3.0.

This fact has shaped the evolution of White Sands’ animal inhabitants, the most conspicuous of which are lizards. Although few large predators can handle the debilitating heat and drought of this habitat, birds of prey pose a serious threat to reptiles that must spend part of their days basking in the sun. Against a white background, lizards should be easy for a cruising hawk to pick out.

During my walk I found two lizards, each of which had a different solution to their avian problem. The first, and most obvious, was the little striped whiptail. Whiptails are handsome but poorly camouflaged, with blue heads and tails and black spots above their forearms.

An adult little striped whiptail (Aspidoscelis inornatus). Photo by Joseph DeSisto.

An adult little striped whiptail (Aspidoscelis inornatus). Photo by Joseph DeSisto.

The whiptail above is an adult, around 8 inches in length. The juveniles are far more striking, with electric blue tails and striped bodies.

A baby striped whiptail. Photo by Joseph DeSisto.

A baby striped whiptail. Photo by Joseph DeSisto.

Little striped whiptails are obvious, but nearly impossible to catch by hand. Almost always, by the time I saw one, it was already vanishing in a flash of blue, zooming across the sand like the Road Runner cartoon. I saw perhaps forty whiptails during my time at White Sands. The two shown above are the only ones I could photograph before they disappeared into a burrow, usually at the base of a shrub or cactus.

Whiptails are extremely fast and wary -- this makes them frustrating to approach (and photograph). Photo by Joseph DeSisto.

Whiptails are extremely fast and wary — this makes them frustrating to approach (and photograph). Photo by Joseph DeSisto.

After half an hour of chasing whiptails, with little more than sunburnt skin to show for my efforts, I started to notice a second lizard in my patch of sandy scrub. These lizards were slower and easier to photograph, but a little harder to spot.

The bleached earless lizard (Holbrookia maculata). Photo by Joseph DeSisto.

The lesser earless lizard (Holbrookia maculata). Photo by Joseph DeSisto.

The lesser earless lizard is almost synonymous with White Sands — certainly it is the most famous reptile in the park. The species to which it belongs is wide-ranging, found from South Dakota west to southern California and south through central Mexico. In most places, earless lizards are some combination of brown and black — only the populations at White Sands have evolved pure white scales to help them camouflage with the gypsum sand. Their scales even shimmer, to help the lizard mimic the sand’s reflective crystal grains.

A lesser earless lizard. Photo by Joseph DeSisto.

A lesser earless lizard. Photo by Joseph DeSisto.

The White Sands earless lizards are called “bleached” earless lizards, for obvious reasons. Many animals at White Sands have evolved white coloration to match the substrate: both lizard predators (e.g., the Apace pocket mouse) and prey (insects). None are quite as effective as the bleached earless lizard, but all are powerful examples of evolution in action.

A basking earless lizard. Photo by Joseph DeSisto.

A basking earless lizard. Photo by Joseph DeSisto.

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2 responses to “White Sands

  1. Love the pictures. They are beautiful.

    Like

  2. Hello Joseph,

    My name is Susan and I am the content manager of Clapway.com, a US based online publication. I came across your blog and really enjoy the content you have on your site. We would like to discuss a potential collaboration with you. If you’d be interested in working with us, please shoot us an email to content@clapway.com.

    Looking forward to hearing from you.
    Best,

    Susan Xu
    Content Manager at Clapway
    195 Plymouth St #6/17
    Brooklyn, NY 11201
    sx@clapway.com

    Like

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