Meeting Abstract
The Texas Horned Lizards (Phrynosoma cornutum) is a threatened species due to widespread habitat loss, urbanization, and the decline of their primary prey, harvester ants (Pogonomyrmex sp). These ants experience declining populations due to overuse of pesticides and the spread of red imported fire ants (Solenopsis invicta). With its primary prey source in decline, these lizards may supplement their diet with a variety of beetles as a small, but consistent part of their diet. We determined the diversity of available prey by setting pitfall traps in a known Texas horned lizard habitat in North Texas. We determined diet composition by dissecting Texas horned lizard fecal samples found in the study site. We then compared digestive efficiency of horned lizards fed solely harvester ants and solely beetles using bomb calorimetry. Although many potential prey items were available, only harvester ants and beetles were constantly found in fecal samples. Harvester ants made up over 90% of the diet, but remnants of small beetles were found in all samples. Other groups, such as bees and weevils were periodically found, but were rare. Although they make up most of the lizards’ diet, they are unable to digest ants efficiently (~30%). The digestive efficiency with beetles was variable but significantly higher. Therefore, the lizards may be selecting beetles to negate nutritional deficits that may result from an all-ant diet.
