Desert lizards tend to be territorial, which means they will protect a portion of their territory from other lizards of the same species. In the Mojave of California, research has shown that male chuckawallas defend large rocky outcrops against other male chuckawallas. However, they will allow females and juvenile males into their territory. It is not just males who can be territorial.

Desert lizards display a variety of behaviors in order to deter other males. Many species flatten their bodies and bobble their heads to give the appearance of a larger body. A fight may ensue if the male visitor does not leave the area, as is the norm. The male resident is usually the victor and the trespasser leaves quickly.

In captivity, the lizards must measure in a small area. This is usually smaller than their natural territory. When there is only one male present, they will fight until the dominant individual takes over. Then aggressive behavior will decrease. The submissive animal cannot flee because it would eliminate the wild.

This truce, which may seem harmonious to us, is often very stressful for the submissive reptile. Most lizards are not used to a hierarchical relationship, as they will often defend their own territories in the wild. Submissive animals will suffer from stress, which is reflected in the increase of their adrenal glands. They may also experience a decrease in growth and mortality. Researchers from the San Diego Zoo discovered that male iguanas grow slower if they are in the same room as an oversized male. The males can detect each other by smell and sight.

Desert lizards are best handled by separating males. The stress of captivity can be increased by the presence of males who are aggressive. This will reduce your lizards’ health. If you must keep animals together for a short time, make sure to provide them with hiding places or rock piles so they can avoid each other if desired.

The simplest solution is to keep males apart. Females who are gravid will also often be aggressive towards other females. Spiny-tailed female spiny lizards that are gravid can be aggressive towards both males as well as females. They may even cause serious injury to their cage mates. If aggression is shown, separate the gravid spiny-tailed lizards.