Feeding habits and predator-prey size relationships in the whiptail lizard Cnemidophorus oCellifer (teiidae) in the semiarid region oF brazil Raul F. D. SaleS 1,2,4 , leonaRDo B. RiBeiRo 1,3,5 , Jaqueiuto S. JoRge 1,6 , anD eliza M. X. FReiRe 1,2,7 1 departamento de Botânica, ecologia e Zoologia, Centro de Biociências, ufrn. lagoa nova, Cep 59078‑900, natal, rn, Brasil. 2 programa de pós‑Graduação em psicobiologia, ufrn. lagoa nova, Cep 59078‑900, natal, rn, Brasil. 3 Current Address: Colegiado de Ciências Biológicas, uniVAsf, Campus Ciências Agrárias. Cep 56300‑990, petrolina, pe, Brasil. 4 e‑mail corresponding author: raulsales17@gmail.com 5 e‑mail: ribeiro.lb@gmail.com 6 e‑mail: queilto@yahoo.com.br 7 e‑mail: elizajuju@ufrnet.br aBStRact. we studied the diet of the whiptail lizard Cnemidophorus ocellifer (spix, 1825) and the relationships between predator size and prey size in a Caatinga area of northeastern brazil. lizards (n = 111) were collected during the day through active search. in the laboratory, we measured them and registered the number of ingested items of each prey category to order, as well as the dimensions and frequencies of each. the main prey category in the C. ocellifer diet was insect larvae and pupae, followed by or- thoptera, isoptera, Coleoptera and araneae. termites (isoptera) were important only in numeric terms, having negligible volumetric contribution and low frequency of occurrence, an uncommon feature among whiptail lizards. the types and sizes of prey consumed by adult males and females were similar, despite sexual dimorphism in head size. adults and juveniles ingested similar prey types, but differed in prey size. maximum and minimum prey sizes were positively correlated with lizard body size, suggesting that in this population individuals experience an ontogenetic change in diet, eating larger prey items while growing, and at the same time excluding smaller ones. KeywoRDS. body size; Caatinga; diet; lizards; ontogeny; prey size. intRoDuction both intrinsic and extrinsic factors have strong influence on the feeding ecology of lizards (pianka, 1986). rainfall and seasonal fluctuations in avail- ability of food are among the most important ex- trinsic factors (pianka, 1970; magnusson and silva, 1993; rocha, 1996). Foraging mode, body size, sex, and ontogeny are important intrinsic factors influ- encing diet composition (schoener, 1967; huey and pianka, 1981; perry, 1996; Vitt, 2000). the conse- quences of body size on feeding ecology have been studied in diverse taxonomic groups. in some cases, predators exclude smaller prey items from the diet as they grow and add larger items, in such a way that both minimum and maximum prey size increase at similar rates (e.g., Costa et al., 2008; Costa, 2009). in others cases, the predator adds larger items to its diet as it grows, but continues to eat small prey. a positive relationship between predator body size and maximum prey size occurs, but minimum prey size remains constant or increases with a much slighter slope (e.g., scharf et al., 2000; sales et al., 2011). Finally, the predator may not add larger items to its diet as it grows; in this case, minimum and maxi- mum prey sizes are not correlated with body size (dietary specialists; e.g., Vitt et al., 1997a; Colli et al., 2003). the family teiidae is composed of actively forag- ing, sexually dimorphic lizards, distributed through- out the americas (Vitt and Caldwell, 2009). within teiids, the teiinae constitute the most speciose and widespread group, mainly owing to the small-bodied species (less than 100 mm in snout-vent length) un- til recently united in the single genus Cnemidopho‑ rus (collectively known as whiptail lizards). in spite of the overall similarity in morphology and ecol- ogy among its members, molecular studies have not supported the monophyly of Cnemidophorus, and reeder et al. (2002) resurrected the genus Aspidos‑ celis for the north and Central american clade of “Cnemidophorus”. the south american whiptails (the lemniscatus group) currently constitute the ge- nus Cnemidophorus, and are more closely related to the large-bodied teiine genera Ameiva and Kentropyx. these three genera are now known to constitute a monophyletic group that reeder et al. (2002) referred to as “cnemidophorines”. most studied Cnemidophorus populations are known to feed predominantly on termites and insect larvae (e.g., Vitt et al., 1997b; mesquita and Colli, 2003a, b; dias and rocha, 2007; menezes et al., south American Journal of herpetology, 7(2), 2012, 149-156 © 2012 brazilian society of herpetology