The elusive alligator lizard

by Rick LoBello, Education Curator

Not everyone living in the Chihuahuan Desert is familiar with one of the most interesting and least known lizards in our eco-region, the Texas alligator lizard (Gerrhonotus infernalis).  More people in Texas have seen alligator juniper trees than they have alligator lizards.  That’s because they are very elusive and often live in higher elevation habitats like the Chisos Mountains of Big Bend National Park. 

The iNaturalist map below will give you some idea of just where people are seeing this lizard today. 

This species is wide spread across Texas and is not confined to living in the Chihuahuan Desert.  Herpetologists have identified 67 species of alligator lizards around the world. The ones most common to North America, the genera Elgaria and Gerrhonotus, includes 8 species ranging from southern Canada down through Central America.

When I was a park ranger in Big Bend, I hiked the trails in the Chisos Mountains several times a week.  I saw these lizards very infrequently and only on sunny days when they were hunting in the leaf litter and I could hear movement along the trail.

The alligator lizard is the only lizard in the United States with a prehensile tail.  Some say it is a relict species surviving on desert islands like Big Bend’s Chisos Mountains from a period before the last ice age, when most of the region was covered by a temperate deciduous forest.  Imagine a time when the desert was covered by forests with alligator lizards in the trees.

Alligator lizards are members of the Anguidae, a large and diverse family of lizards that includes the legless lizard or glass lizard.   They feed mainly on insects and spiders.  Some may grow to up to two feet long from the tip of the nose to the tail and are large enough to eat small rodents and birds.    

Top and bottom images by Rick LoBello
Cover on 5.18.2020, Casa Grande, Big Bend National Park by Rick LoBello