| Sumario: | In 1990 we studied the seasonal feeding patterns of the Western Marbied Whiptail (Cnemidophorus tigris marmoratus) in sand dunes of central Chihuahuan Desert, México (26° 50’ N, 103° 49' W). The stomachs of 35 males and 20 females were examined and the Importance valué (relative abundance + relativa volume + prey constancy), Shannon-Wiener diversity Índex and intersexual niche overlap (summer and autumn) of prey Ítems were determinad. Adult Isoptera were the most important prey during the three seasons studied (I.V. = 38.8 %, both sexes). Other important food Ítems were Lepidoptera (larvae), Dictyoptera (nymphs). Coleóptera (adults) and Araneae. This lizard showed an average H' = 1.1 and H'v = 2.7 and thus is considerad to have a generalist diet. The intersexual niche overlap was larga in summer and autumn (Ojk = 0.95). There were no differences in prey size between the sexes. The coefficient of variation for prey length (CV-PL) was larger in males, whereas it was smaller for snout-vent length (CV-SVL) in males. Males were significantly larger and heavier than females. The observad differences in body size between sexes might be relatad to differences in finite rate of annual survival among them.
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