This month, we spoke with Dr. Cam Barrows, Conservation Ecologist, Emeritus at the Center for Conservation Biology, University of California Riverside, about chuckwallas— the tough desert lizards found in Chuckwalla National Monument. In this Q&A, he unpacks their survival strategies, striking diversity, and ecological importance.

What are chuckwallas and where do you find them? 

The indigenous Cahuilla called them “áxwal,” a name later anglicized by colonists to “chuckwalla,” naming one of the largest native lizards to the warm deserts of the arid southwest. Chuckwallas are vegetarians, occurring throughout the Mojave, Colorado, Baja California, and Sonoran Deserts, found from the bottom of the Grand Canyon to the southern tip of Baja California. Chuckwallas also occur on several of the isolated islands in the Gulf of California between Baja and the Sonoran mainland. Some of those evolved into larger forms, as large as a medium-sized dog, and are recognized as separate species. 

Why do chuckwallas vary so much in color, and what do the different colors mean? 

Mainland chuckwallas are all considered the same species even though the male colors vary from population to population (the females are more similar among and between populations, all colored a mocha brown). 

In contrast, males on South Mountain in the city of Phoenix are light gray with carrot-orange tails. On Pisgah Crater in the Mojave Desert, they are solid black, black as the lava rocks they live on. In the Coachella Valley they have black heads and legs with cream-colored backs and bellies. In the Chuckwalla National Monument, the males have brick-red backs and bellies and white tails. At the bottom of the Grand Canyon the males are salt and pepper colored. 

Whether white, orange, or black, those tails, the bigger the better, tell female chuckwallas all they need to know about the quality of a male’s territory and so whether to stick around to breed. Males with especially good territories, meaning plenty of edible shrubs, attract multiple females.

Speaking of shrubs – how do chuckwallas survive in the desert?

Being a vegetarian in a desert comes with inherent risks. Desert vegetation, by definition, is limited by sporadic, unpredictable rainfall. Therefore, food is sporadic and unpredictable. One way to hedge your bets between plentiful food and famine is to be big to store calories in muscle and fat. Another way is being a reptile with a metabolism based on food availability and temperature. A big, fat chuckwalla can live for a year or more on little food. That said, if drought becomes increasingly common, chuckwalla populations suffer. Chuckwallas therefore can be a bellwether for the effects of climate change. 

Where are chuckwallas most at risk, and where can you still see them?

What we have found is that in the driest regions, low elevations, further east, chuckwalla populations are dwindling. Those at higher elevations, along creeks or seasonally dry stream beds where rare rainfall and/or ground water is concentrated, and/or further west where rainfall is more dependable seem to be doing well, so far.

In the Chuckwalla National Monument, these impressive lizards can be found in bouldery areas along washes. You may not see them but they may be watching you.

Their quiet presence in the desert tells a much larger story about survival, change, and adaptation. Learn more about the different animals you can find at Chuckwalla National Monument by subscribing to our newsletter!