Almost half the lizard species found in the U. S. are present in Arizona. They are a colorful group with fascinating life histories. Lizards help control ants, termites, and other insects, and with only one exception, the Gila Monster, they are unable to seriously harm humans. Field guides are available online (Arizona Herpetological Association, Brennan, 2008), and in print (Jones and Lovich, 2009, and Stebbins, 1966).
The most common species seen around homes in the upper Agua Fria River Basin where I live are the Plateau Fence Lizard, the Ornate Tree Lizard, and several Whiptails and Horned Lizards (HLs–also called horny toads). Here they are active from March to November. In the Sonoran Desert at the south end of the Basin they are active all year. Lizard body temperature is controlled by surroundings rather than by internal systems. Without warm air, sunlight, or sun-warmed surfaces, they have to find shelter.
The photograph shows a Plateau Fence Lizard on a tree. These lizards do like fence posts, but they will sit on any convenient object that gives them an elevated view.
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Children like lizards almost as much as they like turtles. Lizards are not as easy to play with, but they are very brave and colorful, and some are easy to catch. If you haven’t tried to pick up a ground hugging HL, or seen one squirt blood from its eyes you’ve missed out on some of life’s finest experiences. It’s hard to imagine how blood squirting evolved as a defense, but I’ve read that HL blood is distasteful to some predators. When threatened, HLs and many other lizard species puff up their bodies and do pushups to make themselves appear larger and scarier. Some lizards have detachable tails that can be regrown. When cornered, they wave their tails to lure predators into striking that detachable and replaceable appendage.
Newly hatched lizards have to begin hunting food immediately. Only the young of a few skink species receive any parental care, and then not much. A tiny tree lizard less than one inch long, will investigate every small object it finds. Since anything might be dangerous instead of delicious, these tiny creatures will approach a twig, pebble, or clod of dirt, do some pushups, then try a bite. Tiny slugs, ants, and other small arthropods are what they need. Bite-sized morsels themselves, most baby lizards don’t grow up. Those that do join the ranks of one of our most important regulators of bug populations.
Lizards are not descended from dinosaurs. They appeared about the same time and lived with dinosaurs, but they are not closely related. Lizard legs extend to the sides of the body rather than projecting downward or forward. They became a separate group in the Late Triassic, over 200 million years ago.
Almost all of Arizona’s lizard species are declining in response to human developments. The Arizona Game and Fish Department (AZGF) defines over half of the state’s species as ‘vulnerable,’ almost one third as Species of Greatest Conservation Need. Roads, houses, pesticides, invasive species, wildfire, energy development and transmission, and more are steadily eroding their numbers. Species such as the HLs have almost no ability to survive their encounters with humans. Easily captured, they are often taken as pets or specimens, an experience they often do not survive.
The year, 2012, was designated The Year of the Lizard, to draw attention to the conservation needs of lizards. The PARC (Partners in Amphibian and Reptile Conservation) website provides access to special reports and newsletters containing interesting information about lizards.
Further information on conservation is available on the Internet sites listed in the references. A good discussion of lizard conservation is provided in the book by Jones and Lovich (2009).
*Data from and Reptile and Amphibian Ecology International. AZGF lists 17 of these 29 as ‘Species of Greatest Conservation Need.’
AZGF (Arizona Game and Fish Department): http://www.azgfd.gov.
Arizona Herpetological Association: http://www.azreptiles.com.
Brennan, T.C. 2008. Online field guide to reptiles and amphibians of Arizona: http://www.reptilesofaz.com/.
International Reptile Conservation Fund: http://www.ircf.org/.
Jones, L.L.C., and R.E. Lovich, eds. 2009. Lizards of the American Southwest: A photographic field guide. Rio Nuevo Publishers, Tucson, AZ. 567 p.
PARC (Partners in Amphibian and Reptile Conservation): http://www.parcplace.org/.
Stebbins, R.C. 1966. A field guide to western reptiles and amphibians. Houghton Mifflin, Boston, MA. 279 p.
Arizona Lizards Checklist
I couldn’t find a list just for the Agua Fria River Basin. The diverse habitats of the Basin support many of the State’s species occur, so I included the full state list. Lizards listed by AZGF as Species of Greatest Conservation Need are marked with an asterisk (*).
|Anguidae (glass and alligator lizards)|
|Madrean Alligator Lizard (Elgaria kingie)|
|Western Banded Gecko (Coleonyx variegates)
|* AZGF lists subspecies Utah Banded Gecko (Coleonyx variegatus utahensis) as in need.|
|Mediterranean Gecko (Hemidactylus turcicus)|
|Helodermatidae (Gila Monsters)|
|Gila Monster (Heloderma suspectum)|
|Great Basin Collared Lizard (Crotaphytus bicinctores)|
|Eastern Collared Lizard (Crotaphytus collaris)|
|Sonoran Collared Lizard (Crotaphytus nebrius)|
|Long-nosed Leopard Lizard (Gambelia wislizenii)|
|Desert Iguana (Dipsosaurus dorsalis)|
|Common Chuckwalla (Sauromalus ater)|
|Zebra-tailed Lizard (Callisaurus draconoides)|
|Greater Earless Lizard (Cophosaurus texanus)|
|*||Sonoran Elegant Earless Lizard (Holbrookia elegans)|
|Common Lesser Earless Lizard (Holbrookia maculate)|
|*||Texas Horned Lizard (Phrynosoma cornutum)|
|Goode’s Horned Lizard (Phrynosoma goodei )|
|Greater Short-horned Lizard (Phrynosoma hernandesi)|
|*||Flat-tailed Horned Lizard (Phrynosoma mcallii)|
|Round-tailed Horned Lizard (Phrynosoma modestum)|
|Desert Horned Lizard (Phrynosoma platyrhinos)|
|Regal Horned Lizard (Phrynosoma solare)|
|Twin-spotted Spiny Lizard (Sceloporus bimaculosus )|
|Clark’s Spiny Lizard (Sceloporus clarkia)|
|Southwestern Fence Lizard (Sceloporous cowlesi)|
|Common Sagebrush Lizard (Sceloporous graciosus)|
|Yarrow’s Spiny Lizard (Sceloporus jarrovii)|
|Desert Spiny Lizard (Sceloporus magister)|
|*||Slevin’s Bunchgrass Lizard (Sceloporus slevini)|
|Plateau Fence Lizard (Sceloporous tristichus)|
|Yellow-backed Spiny Lizard (Sceloporus uniformis)|
|*||Striped Plateau Lizard (Sceloporus virgatus)|
|*||Yuman Fringe-toed Lizard (Uma rufopunctata)|
|*||Mohave Fringe-toed Lizard (Uma scoparia)|
|Long-tailed Brush Lizard (Urosaurus graciosus)|
|Ornate Tree Lizard (Urosaurus ornatus)|
|Common Side-blotched Lizard (Uta stansburiana)|
|* AZGF lists Hernandez’s Short-horned Lizard (Phrynosoma hernandesi hernandesi) as in need|
|*||Mountain Skink (Plestiodon callicephalus)|
|*||Gilbert’s Skink (Plestiodon gilberti) AZGF lists the subspecies, Arizona Skink (gilberti) in need|
|Many-lined Skink (Plestiodon multivirgatus)|
|Great Plains Skink (Plestiodon obsoletus)|
|Western Skink (Plestiodon skiltonianus)|
|Teiidae (whiptails and tigers)|
|*||Arizona Striped Whiptail (Aspidoscelis arizonae)|
|Canyon Spotted Whiptail (Aspidoscelis burti)|
|Chihuahuan Spotted Whiptail (Aspidoscelis exsanguis)|
|*||Gila Spotted Whiptail (Aspidoscelis flagellicauda)|
|New Mexico Whiptail (Aspidoscelis neomexicana )|
|*||Pai Striped Whiptail (Aspidoscelis pai)|
|Sonoran Spotted Whiptail (Aspidoscelis sonorae)|
|Tiger Whiptail (Aspidoscelis tigris)|
|Desert Grassland Whiptail (Aspidoscelis uniparens)|
|Plateau Striped Whiptail (Aspidoscelis velox)|
|*||Red-backed Whiptail (Aspidoscelis xanthonota)|
|Xantusiidae (night lizards)|
|*||Arizona Night Lizard (Xantusia arizonae)|
|*||Bezy’s Night Lizard (Xantusia bezyi)|
|Desert Night Lizard (Xantusia vigilis)|