Relative feeding specialization may depress ontogenetic, seasonal, and sexual variations in diet: the endemic lizard Cnemidophorus littoralis (Teiidae)

Abstract

We investigated the feeding habits of the teiid lizard Cnemidophorus littoralis in the markedly seasonal habitat of Restinga da Barra de Maricá (22 degrees 57'S, 43 degrees 50'W), Rio de Janeiro State, Brazil, to evaluate to what extent its diet is ontogenetically, sexually, and/or seasonally conservative. Lizard stomach contents were analyzed, identified, counted, estimated for volume (in mm3), and grouped in four classes (active, sedentary, and clumped preys, and plant material). The relative contribution of each food class to the total prey volume consumed by adult males and females and juveniles was compared in three ways: between juveniles and adults, sexes, and seasons (wet and dry). Sexual dimorphism in head size was tested by comparing head width and jaw length using analysis of covariance (ANCOVA). Isopterans were the most important prey item, occurring in 93% of the lizard stomachs examined and corresponding to 96.4% of total prey content and 69.7% of total prey volume. They occurred in high frequencies in the stomachs of C. littoralis throughout all study months. We found no sexual, ontogenetic, or seasonal differences in C. littoralis diet although the sexes differed significantly in head width. We concluded that isopterans are the main item in the diet of C. littoralis in Restinga da Barra de Maricá, both for juveniles and adults. The lack of seasonal, sexual, or ontogenetic variation in its diet results from the massive consumption of these insects. Isopterans are small, occur in clumps, and are available year-round, and thus are an advantageous food item for the active forager C. littoralis. We also found sexual dimorphism in the head size of C. littoralis: males have wider heads than females. This dimorphism, however, does not seem to be related with the diet of the species, and is probably a result of sexual selection.

Diet of the toad Rhinella icterica (Anura: Bufonidae) from Atlantic Forest Highlands of southeastern Brazil

“…The absence of a significant relationship between the prey size ingested and R. icterica size at Itatiaia National Park may be the result from the high consumption of ants, which are preys of small size and little size variation (which reduces the total prey volume in the toads' diets). This trend has been also found in Leptodactylus marmoratus (Teixeira-Filho et al 2003). The difference of 27.4 mm between the highest and lowest toad and 7.1 mm between the highest and lowest jaw may not have been sufficient to establish a relationship with diet.…”

Reptiles Del Bosque Seco Estacional en El Caribe Colombiano: Distribución De Los Hábitats Y Del Recurso Alimentario

“…En condiciones naturales el espectro de recurso disponible cambia constantemente ya sea por variaciones geográficas (distribución de las especies), o temporales (anual y estacional) (Teixeira-Filho et al, 2003;Manjarrez, 2005). Cuando ocurren cambios en el paisaje, por acción antropogénica como la fragmentación y pérdida de coberturas vegetales, se afecta la disponibilidad, abundancia y riqueza del recurso disponible (Carvajal y UrbinaCardona, 2008).…”

Diet of the lizard Liolaemus occipitalis in the coastal sand dunes of southern Brazil (Squamata-Liolaemidae)

“…Seasonal variations in diet are usually associated with the availability of prey in the environment. This variation was verified in Cnemidophorus tigris BAIRD andGIRARD, 1852 (Pianka, 1970), Polychrus acustirostris SPIX, 1825 (Vitt and Lacher, 1981), Iguana iguana (LINNAEUS, 1758) (Schoener et al, 1982), Plica plica (LINNAEUS, 1758) (Vitt, 1991), Tropidurus itambere (RODRIGUES, 1987) (Van Sluys, 1995), Mabuya macrorhyncha (HOGE, 1946) (Vrcibradic and Rocha, 1995), Liolaemus lutzae (MERTENS, 1938) (Rocha, 1996), Tropiduru torquatus (WIED-NEUWIED, 1820) (Fialho et al, 2000) and C. littoralis (ROCHA, ARAÚJO, VRCIBRADIC and COSTA, 2000) (Teixeira-Filho et al, 2003). Ontogenetic variations may appear in the size or type of prey.…”