I have observed this quite often in captive study groups and wild groups of SD Coast HLs. I have also observed it Desert, Roundtail, Texas, Regal, Flattail, and Shorthorned HLs. It is a reflex action that clears the throat of ants and other material that may become lodged in the passageway. It occurs most often when the HLs eat any ant of the genus Pogonomyrmex, which are fairly large in size, but also occurs when eating smaller ants of other genus. Messor pergandi is a much smaller ant without a significant sting, but it still causes SDCHLs, and other species of HLs, to "burp." Is it "normal?" That depends on what you term normal. It happens with regularity in some cases and not in others. It does not produce negative reactions to the horned lizards. It is not a sign of physical abnormalities or health issues.

Lester G. Milroy III
Conservation Biologist