Background Color Matching in Texas Horned Lizards (Phrynosoma cornutum)

Abstract. Most of the literature on the basic ecology of Texas Horned Lizards (Phrynosoma cornutum) cites “cryptic color pattern” as their first line of defense against predation, and yet the degree to which Texas Horned Lizards color match their backgrounds has never been quantified. Several zoos and state wildlife agencies are releasing captive-bred and translocated lizards to parts of their former range. Background color matching may be important to consider when moving lizards into a new habitat where predation may be higher if they are not closely color matched to the local soils. We asked whether lizards more closely match their local soil colors and sun-bleached plant stems than soils and stems from other areas. We found that lizards more closely match their local soil colors than they do the soil colors of other areas and that their vertebral white stripe matches sun-bleached plant stems more than other objects in their environment. We also present background color-matching variation for this taxon in Texas, New Mexico, and Mexico from in situ photos taken, as found, in the wild. We suggest that zoos and wildlife agencies score coloration in their captive populations of lizards, thus possibly enabling these institutions to objectively consider color matching a priori as an applied conservation strategy to potentially increase the survival of reintroduced Texas Horned Lizards.