Diet of the rattlesnake Crotalus durissus in southeastern Brazil (Serpentes, Viperidae)

Abstract

Gut contents of 633 live rattlesnakes from southeastern Brazil received at the Butantan Institute, SP, Brazil between 1993 and 1995 were studied. The snakes were weighed, measured and sexed. Two hundred and fifty‐nine rattlesnakes had stomach and/or intestinal contents. Prey size was estimated by comparison of prey items with specimens from museum collections. Rodents and small marsupials were the main prey eaten by the rattlesnakes, and only 1% of the items were found in the stomach, whereas 41% of the individuals in the sample had feces in the intestine. There was low correlation between size of snake and prey size. No seasonal difference in frequency was found between fed and not fed males, but the occurrence of fed females was significantly lower during summer than winter months (28.9% and 51.8%, respectively). Fed newborn rattlesnakes had the lowest frequency, and also fed on rodents. O conteúdo do trato digestivo de 633 cascavéis do sudeste brasileiro recebidas pelo Instituto Butantan, SP, Brasil entre 1993–1995 foram estudados. As serpentes foram pesadas, medidas e tiveram seu sexo determinado. Duzentas e cinqüenta e nove serpentes apresentaram conteúdo estomacal e/ou intestinal. O tamanho das presas foi estimado comparando‐os com espécimes de museu. Roedores e pequenos marsupiais foram as principais presas ingeridas pelas cascavéis, e somente 1% dos itens foram encontrados no estômago, entretanto 41% das cascavéis tinham fezes no trato intestinal. Houve pequena correlação entre o tamanho da serpente e da presa ingerida. Não foi observada diferença sazonal na freqüência de machos com e sem conteúdo, mas a ocorrência de fêmeas sem conteúdo foi significativamente menor nos meses de verão do que nos meses de inverno (28,9% e 51,8%, respectivamente). Cascavéis recém‐nascidas também se alimentam de roedores e têm a mais baixa taxa de animais com conteúdo.