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Reptiles of the Southwest Desert- Lizards


Page 1: Rattlesnakes
Page 2: Cougars

Page 3: Coyote
Page 4: Lizards
Tamarisk Beetles


There are about 12 species or subspecies of lizards common to the Four Corners Region. Many of these are readily visible on a typical afternoon visit to the region. There are a few species however, including the Utah Night Lizard, that remain a bit more elusive or are peculiar to a certain location. Below are a few photos of the more common lizards you might see on your visit. Most of the following information comes from Geoffrey Hammerson's detailed and informative book Amphibians and Reptiles in Colorado, Revised Edition. If you have an interest in reptiles and amphibians of the Four Corners region I highly recommend this field guide.



I must include an identification disclaimer- I am not a herpetologist, I have never studied lizards other than through observation in the field for fun. If you find any mistakes in my identification or descriptions, please notify me and I will remedy the situation immediately- email Gerald. Any help in properly presenting anything on this web site is always appreciated.

Collared Lizards

There are two species (of eight total) of collared lizards found in the Four Corners region. The species most commonly seen and photographed is the western collared lizard, Crotaphytus collaris baileyi. It is the more colorful of the two, as seen in the photographs below. The second species is the desert collared lizard, Crotaphytus insularis. Both species range in size from about 3 to 4 1/2 inches not including tail (SVL- snout to vent length). Maximum length for each species is about 14 inches or 36 cm. Females during breeding season exhibit orange-red bars on neck and spots on side of body. Females are slightly smaller than males. Collared lizards have a non-regenerative tail.

Collared lizards begin to hibernate in late August and September, emerging again in March or April.

These unmistakable lizards are very fast runners, often glimpsed peripherally as they make their way across open ground, as a flash of bright color. They may be seen running on only their hind legs. Male collared lizards defend their territory, especially during breeding season. They will attack other lizards and can bite with enough force to break the skin.


A beautifully colored western collared lizard (male).


Another western collared lizard, showing color variation (male).

 

Desert Spiny Lizard

The desert spiny lizard, Sceloporus magister cephalaflavus, is another unmistakable species. Its robust size, coloration and prominent scales give it away. Color is a mixture of buff, yellow, and brownish scales. Look for the wedge-shaped black patch at the shoulder. As with collared lizards, sexual dimorphism is present- see photo of sunning pair below. Snout to vent length is 3 3/4 to 51/2 inches. Total length reaches about 13 inches.

According to Hammerson, desert spiny lizards are commonly seen from May to September, but may be seen a month earlier or later if warm weather persists.

Males defend their territory against other males aggressively, and engage in the typical lizard push-up displays for intruders, including humans. Desert spiny lizards are active tree climbers and can often be seen climbing high into trees to avoid contact. I have seen them many times in cottonwood trees throughout southeastern Utah.


Desert spiny lizard- a very large one, on the bank of the San Juan River.


A pair of desert spiny lizards, female on left and male on right, Cross Canyon, Utah- Colorado border.

 

Side-blotched Lizard

The side-blotched lizard, Uta stansburiana, can be identified, as the name might imply, by the dark spot on its side just behind the forelimb. This spot may not always be present. Snout to vent length ranges from 1 1/2 to 2 3/8 inches.

Side-blotched lizards will readily lose their tails. Hammerson notes that many adults have missing or regenerating tails. Sexual dimorphism is present, with males being larger in size.

Side-blotched lizards may be seen as early as March and as late as November. Both males and females perform push-up displays when confronted.

side blotched lizard sunning, Cross Canyon area, Utah- Colorado border.
A side-blotched lizard sunning, Cross Canyon, Utah- Colorado border.

side blotched lizard on sandstone.


I am still trying to positively identify this little lizard that was very gregarious- it just crawled right onto my hand. Based on coloration and spotting, size, and the fact that it had lost its tail, I guessed it was a side-blotched, although it lacked the spot behind the front leg. According to various field guides tail loss is common in side-blotched lizards, and the spot on its side may or may not be present, based on various factors such as sex, age, and geographic location. We encountered this one right along the San Juan River living in the tamarisk as it was eating ants. It was only about 1 1/2 inches in length.

Eastern Fence Lizard (Northern Plateau Lizard)

There are four sub-species of eastern fence lizards (Sceloporus undulatus), also known as prairie and plateau lizards, discussed in Hammerson's volume. At least one sub-species resides in east and southeast utah, Sceloporus undulatus elongatus, also known as the northern plateau lizard.

Snout to vent length ranges from about 1 5/8 inches to 3 3/4 inches. Identifying characteristics include dark bands across back (may or may not be present- variation can be caused by age and sex), blue patch on throat- usually divided at center in elongatus but may not be, and dark bands along sides (may or may not be present). There seems to be considerable variation within and across each sub-species by age, sex, and geographic location. Similar in appearance is the sagebrush lizard.

According to Hammerson, females may lay two clutches of eggs, one as late as July or early August. Each clutch averages about 8 eggs.

sceloporus undulatus elongatus, eastern fence lizard, a.k.a. northern plateau lizard
Photo of Sceloporus undulatus elongatus, or northern plateau lizard, taken near Moab, Utah. Lizard measures about 3 inches, SVL.

Tree Lizard

Until it was pointed out to me that the photo below is in fact an tree lizard, or Urosaurus ornatus, I did not know that I had ever seen one. I had misidentified it as an eastern fence lizard. Looking closely at this photo and the photo above, note the smaller scales and longer tail of the tree lizard. Thanks to the Utah state biologist who pointed this out.

A smaller lizard, the maximum SVL for this species is about 55 mm, with no sexual dimorphism evident. According to Hammerson and his Colorado data, they are active April through October, throughout the entire day, from 8 am to about 8 pm. They are found in canyons and other areas with steep exposures and rocks outcrops. Hammerson states they can be found perching on the base of trees ( juniper and cottonwood), and also in piles of flood-deposited wood. Again, from hammerson's Colorado data, deposition of eggs by females occurs in late-May through July, with one or two clutches produced, possibly according to the age of the lizard.

gravid female sceloporus undulatus elongatus, eastern fence lizard
Photograph above shows apparently gravid female Urosaurus ornatus, or Tree Lizard. Note protuberance just forward of back leg- eggs soon to be laid. Photo was taken 10 August 2009 along the Escalante River in Utah.

Longnose Leopard Lizard

This is another lizard that eluded me for a long time. Then all of a sudden it started showing itself. I am not sure if this has to do with natural cycles in the lizard's life, or me being more observant. I have seen these lizards on the San Juan River near Chinle Creek, and on the DIrty Devil River at Happy Canyon and up Poison Spring Canyon.

The longnose leopard lizard, Gambelia wislizenii, according to Hammerson, exhibits a "relatively low reproductive rate and low population density". Their activity season is short, emerging in mid-May and retreating underground by early August. This is Hammerson's observation for Colorado, by he says that it is also true for Utah.

Leopard lizards are active 2-6 hours after sunrise, actively hunting for food till about noon, according to Hammerson. Leopard lizards will sometimes freeze in place when confronted, or as I have found, run very fast, far away into heavier brush where they can hide. They prefer sparsely vegetated surroundings with lots of open space between brush. Hammerson notes that they seems to occur "only where soil mounded at the base of shrubs is riddled with rodent burrows" which they use for nightly refuge and hibernation. He also states that these lizards can inflict a painful bite.

Sexual dimorphism is present, with females being a bit larger in size. Average male SVL is 12 cm, while average female SVL is 14.5cm. Total length can be up to 38cm.


This photo shows a beautiful female longnose leopard lizard, Gambelia wislizenii . She sat still for some time and allowed me to take a bunch of photos. On all other occasions when I encountered this species, they ran far away and disappeared. Hammerson points out that they "typically flee many meters away", and do so at fast speeds.


This photo shows- I believe- a male of the species. Males are typically smaller in size and lack the bright orange-red coloration that the females show during breeding season.


Lizards Not Pictured

Additional species that you may encounter in the Four Corners Region include both the plateau and western whiptail, sagebrush lizard, Utah night lizard, and short-horned lizard. I will post more details on these species as time allows and make it a point to photograph them whenever I get the chance.



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Page 1: Rattlesnakes
Page 2: Cougars
Page 3: Coyote
Page 4: Lizards
Tamarisk Beetles





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