Perhaps the main advantage reptiles possess is the efficient use of food. Typically, a reptile has one-seventh the metabolic rate of a similarly sized mammal. This translates to one seventh the amount of food needed to survive during active periods. This also means reptiles breathe less often, conserving water that would otherwise be lost. Most deserts, including Anza-Borrego, are very undependable in providing a steady supply of food for carnivores.
Reptiles easily go into dormancy during warm months or hibernate in winter surviving on stored fat.
This ability to survive prolonged drought is a distinct advantage for reptiles. Due to their limited ability to travel long distances, reptiles must be able to obtain sufficient water solely from their food. The remaining water is lost equally via respiration and through the skin. All reptiles possess a thick, scaly skin composed of pliable alpha keratin on the inner surface and stiffer, harder beta keratin on the outer exposed surface. Keratin is the structural protein found in human nails and in bird feathers.