7 CONGRESSO NAZIONALE

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2 7 CONGRESSO NAZIONALE Oristano, Promozione Studi Universitari Consorzio1, Via Carmine (c/o Chiostro) 1-5 ottobre 28 Esempio di citazione di un singolo contributo/how to quote a single contribution Angelini C. & Utzeri C., 28. Survival analysis of two populations of Salamandrina perspicillata (pp ). In: Corti C. (ed.), 28. Herpetologia Sardiniae. Societas Herpetologica Italica/Edizioni Belvedere, Latina, le scienze (8), 54 pp.

3 Herpetologia Sardiniae Food habits of Archaeolacerta bedriagae (Reptilia: Lacertidae). Pierluigi BOMBI, Daniele SALVI & Marco A. BOLOGNA Dipartimento di Biologia, Università Roma Tre - Viale G. Marconi, Roma, (Italia) < bombi@uniroma3.it > < salvi@uniroma3.it > < bologna@uniroma3.it > Key words: Bedriaga s Rock Lizard, Feeding strategy, Eco/geographical correlates, Sardinia. Archaeolacerta bedriagae (Camerano, 1885) is a rock lizard endemic to Sardinia, Corsica, and related satellite islands. In both islands it occurs from sea level to the highest mountains (27 m a.s.l. M. Cinto in Corsica and 19 m a.s.l. Gennargentu Massif in Sardinia). Despite having a wide altitudinal distribution, it is a strictly rock-dwelling lizard (Bombi, 25) that is confined to large rocky outcrops. To date, only few studies examined the ecological requirements of this species (Castilla et al., 1989; Vanhooydonck & Van Damme, 1999; Vanhooydonck et al., 2, Bombi et al., in press) and only one dealt with A. bedriagae diet composition (Castilla et al., 1989). Despite lizards were one of the most popular subject for studies on feeding ecology, the preliminary study of Castilla et al. (1989), based on 12 specimens, is the only available on A. bedriagae. Thus, an improvement of our understanding of food habits of this species is an important step in the definition of its ecological requirements. This study is aimed at describing the feeding strategy of this poorly-known species. Field research was carried out on April, May, July and September of the period The study area is located in Gallura, in northern Sardinia including mountain, coastal, and insular localities. Lizards were captured with a noose, sexed, measured, marked (to avoid recaptures), and released. Diet composition were studied by analysing faecal pellets that lizards excreted during manipulation. Faecal pellets of 31 lizards from seven localities were employed, being two insular (La Maddalena and Caprera islands), three coastal (Punta Falcone, Capo d Orso, Mount Moro), and two mountain (Punta Balistreri and Punta Lu Scioccu in the Limbara Mountains) (for geographic references see Bombi & Vignoli, 24). All the food samples obtained were examined by using a stereomicroscope and all food items found were identified to the finest reachable taxonomic level. The representativeness of data was tested by elaborating cumulative curves. A modification of the graphical Costello method (199) proposed by Amundsen et al. (1996), was utilized to represent the feeding strategy of this species. In the 87

4 TOT Figure 1. Trophic spectrum of Archaeolacerta bedriagae. Number of food items per prey taxa found in faecal pellets. Amundsen plot, frequency of occurrence of each food item is plotted against its prey-specific abundance, defined as the proportion a prey item (i) comprises of all prey items in only predators that contain prey i (Amundsen et al., 1996). The diet of Bedriaga s rock lizard consists mainly of Arachnida, Hemiptera, Diptera and Hymenoptera (Fig. 1). The feeding strategy of the species resulted to be highly generalist, being the points representing prey taxa in the bottom left area of the Costello s graphics (Fig. 2). These results allowed us at defining A. bedriagae as a generalist predator. Nevertheless, a preliminary analysis of intraspecific alimentary differences among insular, coastal, and mountain populations (data not shown) suggests that this species can change its food habits site by site in response to different ecological conditions, including in its diet opportunistically preys according to their local availability. Notwithstanding the presented data, as well as those presented by Castilla et al. (1989), are intended to be preliminary and should be implemented before getting definitive conclusion, a raw picture of the trophic spectrum of A. bedriagae could be drawn. Differently from Castilla et al. (1989), we did not find Oligochaeta in faeces of the Bedriaga s rock lizard. Actually, A. bedriagae is a strictly rock dwelling lizard (Bombi et al., in press) that rarely have the chance of encountering earthworms in its microhabitat. Moreover the tissues consistency of Oligochaeta makes highly improbable recovering remains of this taxon in digested pellets. Vegetal material was no detected, despite of Castilla et al. (1989) observed remnants of vegetables in 6 out of 12 individuals, being the exclusive contents in two of them. In the case that a more exhaustive analysis of our data 88

5 1 Frequency of occurrence tot Prey-specific abundance tot Figure 2. Trophic strategy of Archaeolacerta bedriagae. will confirm the absence of vegetables from faecal pellets (Bombi & Salvi, unpublished), it should be also reconsidered the conclusions of Van Damme (1999), who defined A. bedriagae as partially herbivorous. References Amundsen P.A., Gabler H.M. & Staldvik F.J., A new approach to a graphical analysis of feeding strategy from stomach contents data - modification of the Costello method. J. Fish Biol., 48: Bombi P., 25. Range fragmentation in some species of genus Archaeolacerta s.l.: causes and effects. PhD Thesis, University of Roma Tre, 79 pp. Bombi P. & Vignoli L., 24. Distribution, ecology and conservation of Archaeolacerta bedriagae in Sardinia (Reptilia, Lacertidae). In: Bologna M.A. & La Posta S. (eds.), The conservation status of threatened amphibian and reptile species of the Italian fauna. Ital. J. Zool,. 71, Suppl. 1: Bombi P., Salvi D., Luiselli L. & Bologna M.A., in press. Modelling correlates of microhabitat use of two sympatric lizards: a model selection approach. Animal Biology. Castilla A.M., Bauwens D., Van Damme R. & Verheyen R., Notes on the biology of the high altitude lizard Lacerta bedriagae. Herpetol. J., 1: Costello M.J., 199. Predator feeding strategy and prey importance: a new graphical analysis. J. Fish Biol., 36: Gotelli N.J. & Graves G.R., Null models in ecology. Smithsonian Inst. Press. Washington Van Damme R., Evolution of herbivory in Lacertid Lizards: effects of insularity and body size. J. Herpetol., 33: Vanhooydonck B. & Van Damme R., Evolutionary relationships between body shape and habitat use in lacertid lizards. Evol. Ecol. Res., 1: Vanhooydonck B., Van Damme R. & Aerts P., 2. Ecomorphological correlates of habitat partitioning in Corsican lacertid lizards. Funct. Ecol., 14: