Retention time of digesta in insectivorous lizards—a comparison of methods and species

Abstract

We measured retention time in the six-lined racerunner, Cnemidophorus sexlineatus, using three different methods simultaneously. This enables us to compare methods, assess retention time of various phases of the lizard’s digesta, and compare the data with other studies, species and methods. Our study reveals that: (1) Total mean retention time for C. sexlineatus was 20.1–23.7 h, the shortest TMRT measures for insectivorous lizards. (2) There was no detectable separation of solid, aqueous, or lipid phases in the digesta of the lizard, probably due to the rapid transit time relative to the frequency of defecation. Studies of lizards with greater retention times indicate separation of liquid and solid phases, but have not tested phase specificity of the markers. Separation of lipid and aqueous phases is important, as was reported before for certain mammals and birds. This is the first study to look for separation of lipid and aqueous phases in reptiles.