Marta Biaggini and Claudia Corti
Human activities cause increasingly deep alterations to natural environments. Yet, the effects on vertebrates with low dispersal capacity are still poorly investigated, especially at field scale. Life history variation represents one means by which species can adapt to a changing environment. Among vertebrates, lizards exhibit a high degree of variation in life-history traits, often associated with environmental variability. We examined the female breeding output of Podarcis siculus (Lacertidae) inside agricultural habitats, to test whether different cultivation and management influence the life-history traits of this species. Interestingly, we recorded variability of female breeding output at a very fine scale, namely among adjacent vineyards and olive orchards under different management levels. Lizards displayed the lowest breeding effort in the almost unmanaged sites, while clutch mass, relative fecundity and mean egg mass slightly increased in more intensively managed sites. However, in the most intensive cultivations we detected a life-history trade-off, where eggs from larger clutches tended to be relatively smaller than eggs from smaller clutches. This pattern suggests that agriculture can influence lizard reproductive output, partly favouring it in the presence of medium intensity cultivation but causing, in the most intensively managed sites, some environmental constraints that require a peculiar partitioning of the breeding resources. Even though further studies are needed to clarify the mechanisms driving the observed pattern, our results can be considered a starting point for evaluating the analysis of lizard breeding features as a tool to assess the impact of human activities, at least in agricultural environments.
Marco Zuffi and Claudia Corti
Hermann's tortoise (Testudo hermanni Gmelin) of the Island of Asinara (NW Sardinia, Italy) has been studied during a period of four seasons. This population consisted of several individuals of large body size, some of them being amongst the largest known for this species. Bony shells of males were commonly found on this island, while the same was not true for female bony shells. Although wild boars (Sus scrofa) are potential large sized predators for tortoises, the analysis of carapace morphology did not reveal injuries signs due to bites. Male tortoises could die due to up-turning, as the result of male-male combats during the mating season, to possible hyperthermia when upturned, and to predation carried out by birds particularly when upturned. Estimated density was 4.88 individuals ha-1, which was similar to that of conspecifics from other areas studied so far.
Claudia Corti, Marta Biaggini and Roberto Berti
Human agricultural activities can deeply alter the environment thus provoking major impacts on a variety of organisms. Agricultural habitats however can be very different from one another in terms of habitat structure and management intensity, presenting varying pressures and/or benefits for different species. Agro-ecosystems can have opposing effects on reptiles and in some circumstances the presence of a species can even been enhanced by agricultural practices. We focused our study on Podarcis sicula, a relatively widespread lacertid lizard commonly present in agro-environments in Italy. We examined escape behaviour, caudal autotomy rates and ectoparasite load (tick infestation) in populations living in two different land uses, olive tree plantations and vineyards. All three aspects seemed to be deeply influenced by habitat structure. Predation pressure, as evaluated by tail break frequency, was lower in olive tree plantations, the most structurally complex habitats. In this type of habitat lizard escape behaviour was characterised by a clear preference for olive trees as refuges: individuals ran farther distances on average to reach the trees and hid inside them for a relatively long time. In vineyards, on the contrary, a less clear escape strategy was observed, showing a use of more temporary refuges. Also tick (Ixodes ricinus) infestation differed among land uses, being higher in olive tree plantations, probably in relation to vegetation cover features. Differences were found also between managements (with a higher tick load in traditional cultivations) and sexes, with males being more parasitized.
Roger Avery, Annabel Basker and Claudia Corti
Two adult Podarcis muralis whose normal movements incorporated the flat top of a wall, frequently paused so that they were looking outwards from an edge ("scan" posture), especially during longer (≥9 s) periods immobile. Investigations of the posture on raised wooden platforms in outdoor enclosures, using two juvenile lizards, showed that (1) lizards spent significantly more time on platforms than would be expected from random movement, and this was not because wood is a favoured substrate for basking; (2) lizards which were immobile on platforms spent significantly more time at edges than would be expected by chance; (3) body orientations at 67.5-112.5° to the edge were the most frequent and these were maintained for significantly longer periods than the remaining orientations; exceptions were from 0800-0900 h when orientation was often parallel to the edge facing the sun and from 1200-1300 h with only a thin strip of shade at 45°, into which the lizards fitted themselves. Lizards basking in the laboratory beneath a tungsten bulb at the edge of a raised platform adopted outward-facing orientations when the platform height was ≥6 mm. When presented with a choice between basking more effectively (i.e. rapid heating rate) or adopting the "scan" posture at an edge with a lower heating rate or with no heating, they opted for the former. Podarcis sicula, P. filfolensis, Lacerta viridis and L. vivipara all showed an excess of outward-facing orientations when the basking bulbs were place near edges of platforms, but Psammodromus hispanicus did not. Only the two Podarcis species, however, spent more time on raised platforms than would be expected by chance when basking was possible at many sites in an arena.
Ernesto Filippi, Luca Luiselli, Massimo Capula and Claudia Corti
Abstract. The horseshoe snake (Coluber hippocrepis) is one of the most threatened Italian snakes, especially in Sardinia where its present occurrence was unclear. This paper reviews the current distribution of C. hippocrepis in Sardinia, and confirms that this species is still found in a limited number of sites of Cagliari province. Its actual presence in Oristano province, on the contrary, is still in doubt. Statistical analyses on several morphometric measurements taken from museum specimens suggest that snakes from the central Mediterranean area (Sardinia, Pantelleria, and Tunisia) are distinguished from those of the western Mediterranean area (Portugal and Morocco) by having significantly higher numbers of ventrals. A few natural-history notes on Sardinian specimens are presented, and a rationale for an urgent conservation plan is given.
Claudia Corti, Uwe Fritz, Heiko Stuckas and Melita Vamberger
Using mtDNA sequences and 12 microsatellite loci, we compare populations of Testudo graeca from Sardinia and North Africa. The observed pattern of almost no differentiation combined with reduced variation in the Sardinian population is consistent with introduction in prehistoric or historic times from what is now Tunisia and neighbouring Algeria. Furthermore, in the light of the recently published recommendation to eradicate the non-native T. graeca from Italy, we review recent studies on the archaeological and fossil record, on the phylogeography and population genetics of the three other chelonian species occurring in Sardinia (Emys orbicularis, T. hermanni, T. marginata). We conclude that the extant Sardinian populations of all four species are not native. However, they are and should be safeguarded under EC law (Council Regulation No 338/97 on the Protection of Species of Wild Fauna and Flora; Flora Fauna Habitat Directive: Appendix IV, Art. 12) because they serve as a back-up for the declining mainland populations. Moreover, these populations constitute an important part of the human-shaped natural heritage of the Mediterranean.
Luca Luiselli, Valentín Pérez-Mellado, Mario Garrido, Ana Pérez-Cembranos and Claudia Corti
While the use of faecal pellets is widely accepted as a primary methodological source of data for dietary studies, a recent paper advocated for the use of gut contents. This was due to the fact that faecal samples would give biased results of the diet of arthropod predators, due to a lower representation of soft-bodied prey in faecal pellets. To test this assumption, we compared the spring diet of several populations of two insular lizards from the Balearic Islands (Spain), Podarcis lilfordi and Podarcis pityusensis, using both faecal pellets and gut contents. Our results do not support the supposed bias of dietary analyses based on faecal pellets. Indeed, soft-bodied prey and particularly insect larvae are often equally represented in faecal pellets and gut contents. Alternatively, soft bodied prey are represented in different proportions in gut contents and faecal pellets, but in some cases with higher proportions being observed in the gut contents, and in other cases with higher proportions in faecal samples. We conclude that faecal pellets can be a reliable source of information for dietary studies.