Extreme feeding behaviours in the Italian wall lizard, Podarcis siculus

Headnote

Abstract. In the present paper the occurrence of cannibalism, unusual predation on small reptiles [Hemidactylus turcicus (Reptilia, Gekkonidae)], and foraging on small mammal carrion [Suncus etruscus (Mammalia, Soricidae)] by P. siculus is reported.

Keywords. Podarcis siculus, feeding behaviour, predation, Italy.

Podarcis siculus (Rafinesque-Schmaltz, 1810) is a lacertid lizard occurring in Italy and in the northwestern Balkan Peninsula (Corti and Lo Cascio, 2002; Corti, 2006). This lizard is an opportunistic species characterized by broad ecological tolerance and high spreading capacity (Nevo et al., 1972; Gorman et al., 1975). Podareis siculus can be considered as an active forager and a generalist predator (Kabisch and Engelmann, 1969; Pérez-Mellado and Corti, 1993). It preys upon a wide variety of invertebrates, mainly on arthropods (Arachnidae, Insects larvae, Diptera, Coleóptera, Heteroptera, Hymenoptera, Orthoptera, Gastropoda; see e.g. Capula et al., 1993; Rugiero, 1994; Corti and Lo Cascio, 2002; Bonacci et al, 2008; Corti et al, in press), but occasionally small vertebrates can be also preyed (Sorci, 1990; Sicilia et al, 2001). Its feeding behaviour seems to be opportunistic, as indicated by the consumption of different preys in different habitats and/or geographic areas: e.g. the dominant preys are Diptera and Isopoda on the Formica di Burano Islet (Italy); spiders and Coleóptera on Menorca, (Balearic Islands); larvae of insects and ants on the Sparviero islet (Italy) (Pérez-Mellado and Corti, 1993); Coleóptera on Sicily (Sorci, 1990); ants, afids and vegetable matter on the Vivaro di Nerano Islet (Italy) (Ouboter, 1981); Diptera and larvae of Lepidoptera in a urban park (Rome, Italy) (Capula et al, 1993); Isopoda in a coastal dune habitat of central Italy (Rugiero, 1994). Although being a typical insectivorous lacertid lizard, P siculus can also feed on a significant amount of plant matter on some Mediterranean islands (see e.g. Ouboter, 1981; Pérez-Mellado and Corti, 1993; Cooper and Vitt, 2002; Herrel et al, 2008). This behaviour is shared with several other species of the family Lacertidae occurring on Mediterranean islands (Capula and Luiselli, 1994; Pérez-Mellado and Traveset, 1999; Van Damme, 1999). Cannibalism seems to be rare and uncommon (e.g. Ouboter, 1981; Rugiero, 1994; Henle, 1988; Burke and Mercurio, 2002). As to cases of predation on small vertebrates, the only available literature data refer to the prédation of two small individuals Discoglossus pictus (Sicilia et al., 2001), and to undeterminate vertebrate preys observed in the faecal pellets of adult P. siculus (Sorci, 1990).

In the present paper the occurrence of cannibalism and unusual predation on small vertebrates by P siculus is reported. In the first case it was possible to observe a large male P siculus preying upon a juvenile of the same species. This case of cannibalism was observed on 26 September, 2006, at 0930 h a.m., on the side of a dry wall close to the small village Fiumefreddo Bruzio (Province of Cosenza, Calabria, southern Italy). The male P siculus captured the juvenile by hardly biting on the hips of the small lizard. In the second case it was possible to record a female P siculus preying upon a juvenile Hemidactylus turcicus (Reptilia, Gekkonidae). Predation was observed on 20 August 2003, at 0200 h p.m., on the wall of an old building in the historical centre of Fiumefreddo Bruzio village (Province of Cosenza, Calabria, southern Italy). It was also possible to take a picture of this unusual case of prédation (see Fig. 1). This is the first documented case of predation on a gekkonid lizard by P siculus. In the third case, a large male P siculus was observed and photographed feeding upon a carrion of an adult Suncus etruscus (Mammalia, Soricidae) (see Fig. 2). Foraging on carrion was recorded on 16 June 2004, at 1030 h a.m., on one side of a dry wall surrounding a private house garden in the village of Torchiara (Province of Salerno, Campania, southern Italy). This is the first documented case of foraging on small mammal carrion by P siculus.

ACKNOWLEDGMENTS

The authors are gratefully indebted to Bruno Cignini (Roma) for providing useful information and photographic material.

References

REFERENCES

Bonacci, T., Aloise, G., Brandmayr, P., Zetto Brandmayr, T., Capula, M., (2008): Testing the predatory behavior of Podarcis sicula (Reptilia: Lacertidae) towards aposematic and non-aposematic prey. Amphibia-Reptilia 29: 449-453.

Burke, R.L., Mercurio, R.J. (2002): Food habits of a New York population of Italian wall lizards, Podarcis sicula (Reptilia, Lacertidae). Am. Midl Nat. 147: 368-375.

Capula, M., Luiselli, L. (1994): Resource partitioning in a Mediterranean lizard community. Boll. Zool. 61: 173-177.

Capula, M., Luiselli, L., Rugiero, L. (1993): Comparative ecology in sympatric Podarcis muralis and P. sicula (Reptilia: Lacertidae) from the historical centre of Rome: what about competition and niche segregation in an urban habitat? Boll. Zool. 60: 287-291.

Cooper, W.E. Jr, Vitt, L.J. (2002): Distribution, extent, and evolution of plant consumption by lizards. J. Zool., Lond. 257: 487-517.

Corti, C. (2006): Podarcis sicula (Rafinesque, 1810) Italian wall lizard. In: Atlante degli Anfibi e dei Rettili d'Italia, p. 486-489. Sindaco, R., Doria, G., Razzetti, E., Bernini, F., Eds, Polistampa, Firenze.

Corti, C., Lo Cascio, P. (2002): The Lizards of Italy and Adjacent Areas. Chimaira Verlag, Frankfurt am Main.

Corti, C., Biaggini, M., Capula, M., in press. Podarcis siculus (Rafinesque-Schmaltz, 1810). In: Fauna d'Italia. Reptilia, Vol XLV. Capula, M., Luiselli, L., Razzetti, E., Sindaco R., Eds, Edizioni Calderini de Il Sole 24 ORE Editoria Specializzata S.r.l., Bologna.

Gorman, G.C., Soulé, M., Yang, S.Y., Nevo, E. (1975): Evolutionary Genetics of Insular Adriatic Lizards. Evolution 29: 52-71.

Henle, K. (1988): Dynamics and ecology of three Yugoslavian populations of the Italian wall lizard (Podarcis sicula campestris De Betta) (Reptilia: Lacertidae). Zoolog. Anz. 220: 33-48.

Herrel, A, Huyghe, K, Vanhooydonck, B., Backeljau, T., Breugelmans, K., Grbac, I., Van Damme, R., Irschick, D.J. (2008): Rapid large-scale evolutionary divergence in morphology and performance associated with exploitation of a different dietary resource. Proc. Nat. Acad. Sci., U.S.A. 105: 4792-4795.

Kabisch, K., Engelmann, K.E. (1969): Zur Nahrung von Lacerta muralis (Laurenti) in Ostbulgarien. Zool. Abh. 30: 89-92.

Nevo, E., Gorman, G.C., Soulé, M., Yang, S.Y., Clover, R.,. Jovanovié, V. (1972): Competitive exclusion between insular Lacerta species (Sauria, Lacertidae). Notes on experimental introductions. Oecologia 10: 183-190.

Ouboter, P. E. (1981): The ecology of the island-lizard Podarcis sicula salfi: correlations of microdistribution with vegetation coverage, thermal environment and food-size. Amphibia-Reptilia 2: 243-257.

Pérez-Mellado, V., Corti, C. (1993): Dietary adaptations and herbivory in lacertid lizards of the genus Podarcis from western Mediterranean islands (Reptilia: Sauria). Bonner Zool. Beitr. 44: 193-220.

Pérez-Mellado, V., Traveset, A. (1999): Relationships between plants and Mediterranean lizards. Nat. Croat. 8: 275-285.

Rugiero, L. (1994): Food habits of the Ruin Lizard, Podarcis sicula (Rafinesque-Schmaltz, 1810), from a coastal dune in Central Italy. Herpetozoa 7: 71-73.

Sicilia, A., Violani, C., Zava, B. (2001): Predazione di Podarcis sicula su Discoglossus pictus. Atti 3° Congresso Nazionale della Societas Herpetologica Italica (Pavia, 14-16 settembre 2000), Pianura 13: 283-284.

Sorci, G. (1990): Nicchia trofica di quattro specie di Lacertidae in Sicilia. Naturalista siciliano 14 (Suppl.): 83-93.

Van Damme, R. (1999): Evolution of herbivory in lacertid lizards: effects of insularity and body size. J. Herpetol. 33: 663-674.