NOTA

Rodent consumption by Philodryas psammophidea (Serpentes: Colubridae), from the Inter-andean Dry Valleys of Central Bolivia

 

Oliver Quinteros-Muñoz, Diego A. Peñaranda & Freddy Navarro

Centro de Biodiversidad y Genética, Universidad Mayor de San Simón, Casilla 538. Cochabamba, Bolivia. ohlisin@yahoo.es

Recibido: 24/11/10
Revisado: 29/11/10
Aceptado: 01/12/10

 

The genus Philodryas (Wagler, 1830) is composed by opisthoglyphous snakes with terrestrial and diurnal habits, some may also be arboreal. They are medium to large hunters with thin bodies (Thomas, 1976; Cei, 1993, López and Giraudo, 2008). Widely distributed in South America, this genus includes 18 species (Zaher et al., 2008), of which eight have been recorded in Bolivia (Aguayo, 2009).

These snakes feed on a wide variety of small vertebrates, such as lizards, anurans, snakes, birds and small mammals even bats (Thomas, 1976; Funk et al., 2003; Lopez, 2003; Otto and Miller, 2004; Franca and Araujo, 2007). However, the feeding habits of only two species, P. patagoniensis and P. olfersi, have been described in detail (Hartmann and Marques, 2005; Lopez and Giraudo, 2008; Leite et al., 2009). In this sense, P. psammophidea is regarded a herpetophagous snake (Leynaud et al., 2006; Aguayo et al., 2007; Franca and Araujo, 2007).

In May 18, 2009 we found an adult female of Philodryas psammophidea (930 mm SVL), at a side of a crop field in the Tabacal valley (18°23'7.42" S - 64°38'7.88" W, 2015 m), Narciso Campero province southern Cochabamba, Bolivia. Ecologically, this valley belongs to the Inter-Andean Dry Forests of Bolivia (Ibisch and Merida, 2003). In the stomach of the snake probably killed by a settler, there was an adult female of Graomys domorum (Phyllotini; Sigmodontidae), a native rodent species widely distributed in the region. This rodent was ingested head-first recently, because there were no signs of decomposition. Both specimens were deposited in the vertebrate collection of the Centro de Biodiversidad y Genética (P. psammophidea CBG-700.; G. domorum CBG-405).

Despite Philodryas members are considered generalists predators, amphibians and reptiles constitute the most consumed preys, while birds and small mammals occur less frequently and have been reported in the diet of only five species of the genus (P. aestiva, P. baroni, P. nattereri, P. olfersii, P. patagoniensis) (Cei, 1993; Franca and Araujo, 2007). Although P. psammophidea is fed with rodents in captivity (Scrocchi et al., 2006), this is the first formal evidence of small mammals consumption by this snake in wild in Bolivia, and suggests a generalist diet for P. psammophidea as observed in other snakes of the genus.

On the other hand, it is known that the feeding habits of the two best-studied species of the genus, P. olfersii and P. patagoniensis, vary geographically in the dominance of prey types they consume and it has been proposed that such changes may be related to the increased prey availability or detectability, the snakes activity patterns or the phylogenetic relationships among them, instead of a resource preference pattern, as the most consumed prey do not constitute limited resources in the environment (Hartmann, 2001, Hartmann and Marques, 2005, Lopez and Giraudo, 2008, Leite et al ., 2009).

Therefore, considering that rodents are apparently more abundant elements compared with amphibians and lizards in the inter Andean dry valleys southern Cochabamba (Cahill et al., 2010), P. psammophidea could be an important controller of rodents, mainly in those areas close to villages and crop fields where the higher abundances have been observed (D. A. Peñaranda, unpub. data).

ACKNOWLEDGEMENTS

This work is a result of the project Technical Justification for the Establishment of the Pasorapa Integrated Managed Natural Area, funded by American Bird Conservancy and executed by the Center for Biodiversity and Genetics. Authors want to thank to Jennifer R.A. Cahill for her support and encouragement as the general coordinator of the project. To G. Scrocchi whose comments and suggestions helped to improve previous versions of this manuscript. To E. Rocha who found and collected the specimen, O. Osco whose experience with Andean rodents was important, finally to Adam W. Ferguson for providing literature of Philodryas snakes.

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