Strong habitat associations are seen in reptiles. All of the Spiny Lizards are found in habitats with trees or large shrubs: in mesquite, juniper, and crucifixion thorn plant associations and riparian areas. Clark Spiny Lizards and Eastern Fence Lizards are restricted primarily to moist habitats with mature canopy, as are Tree Lizards, Arizona Alligator Lizards, and Ring-necked Snakes. A trend toward moist habitat association is also seen for Night Snakes and Black-tailed Rattlesnakes. Collared Lizards are found only near substantial rock outcrops, and Tree Lizards use the vertical structure as well. Most whiptails are found primarily in grassland vegetative associations, with the exception of the Western Whiptail, which is a habitat generalist. the Western Diamondback Rattlesnake is clearly associated primarily with drier upland habitats. In addition to Western Whiptails and Side-blotched Lizards, the whipsnakes and Patch-nosed Snake are widely distributed, and appear to be rather general in the habitats they use at the monument. Along with cacti and sand dunes, snakes and lizards are icons of the desert. The common reptiles found at Tuzigoot are snakes and liazrds; they are underappreciated, sometimes feared, animals that play an important role in the high-desert ecosystem. Lizards and snakes help control insect and rodent populations. In turn, both are potential meals for birds and mammals. All reptiles are cold-blooded or, more accurately, "ectothermic", regulating body temperature via external sources rather than internal metabolism. A reptiles metabolic rate is very slow, but so are its' energy needs. Since keeping warm in the desert does not require much work, reptiles are well adapted to this environment. What energy they do generate can be used for reproduction and finding food instead of heating and cooling. Of course, there are drawbacks to this lifestyle. Since they don't pant or sweat, reptiles can't endure extremely high temperatures without shade. Nor can they endure prolonged sub-zero temperatures. When it's cold, reptiles hibernate or enter into a state of torpor. Food stored as fat in their tails helps lizards survive these long periods of inactivity, so losing a tail can be life-threatening. If you visit Tuzigoot National Monument during the summer, you are sure to see lots of lizards. After birds, the reptiles are the most active animals once daytime temperatures reach 90 degrees and higher. They are usually visible sunbathing on rocks or chasing insects with their lightning-quick reflexes.