Experimental assessment of Spot-tailed Earless Lizards (Holbrookia lacerata and H. subcaudalis) as visual predators

Plateau Spot-tailed Earless Lizards (Holbrookia lacerata) and Tamaulipan Spot-tailed Earless Lizards (H.subcaudalis) (hereafter STELs) are phrynosomatid lizards that are species of conservation concern. STELs are insectivoresand are thought to be visual predators, but predation strategies have not been empirically documented. We randomlyassigned 15 Plateau and 15 Tamaulipan STELs to one of three predation-behavior treatments: (1) live cricket,(2) dead cricket glued to monofilament line and moved, or (3) dead crickets. Both STEL species attacked only movingcrickets, clearly demonstrating that STELs are visual predators. This has important conservation implications becauseSTELs frequently occupy peripheries of agricultural fields, where pesticides often are used; consequently, feeding onimmobile prey, particularly insects, could have negative consequences for these imperiled lizards.