The Herpetological Journal

pp. 213-219
Authors: Gregory, Patrick T. & Isaac, Leigh Anne

Abstract: Injuries of various types are widespread in animals and presumably have implications at the population level (e.g. reduced future survivorship). We studied patterns of injury acquisition in a population of grass snakes (Natrix natrix) in south-eastern England. Injuries suffered by grass snakes were of various types, including broken bones, assorted scars and wounds, and tail loss. What causes such injuries is unknown, but predators seem most likely. We predicted that the probability of having an injury would be higher for larger snakes, for several reasons (e.g. larger snakes are older and thus have had more opportunity to be injured). We also predicted that injury rates would be higher in females because, when gravid, they are expected to bask in the open more than other snakes. Our data strongly supported the first of these predictions, but not the second. Males had significantly higher injury rates than females of the same body size. However, because males grow more slowly and mature at a smaller body size than females, higher injury rates of males might simply reflect their smaller size at a given age. Even if age plays a role in influencing acquisition of injuries, other, more directly size-related factors also might be important. Two possibilities are that small snakes might be less likely to survive an injury or that small snakes spend more time hidden and so are less likely to encounter large predators. We lack data on the first of these, but data on sizes of snakes found under cover versus those found in the open are consistent with the second. Studies of injury rates in snakes need to move beyond the descriptive stage and begin to test the broader consequences of injuries.

Keywords: SOUTHERN ENGLAND, COLUBRIDAE, NATRICINE, PREDATION, SNAKE, INJURIES

pp. 221-230
Authors: Luiselli, Luca; Filippi, Ernesto & Capula, Massimo

Abstract: The diet of grass snakes (Natrix natrix) on the mainland and an island of Italy was compared by pooling literature data and original data. A total of 535 prey items were recorded (444 prey items from specimens >40 cm SVL), but the number of items was very variable between sites. Body lengths (both sexes) varied between geographical areas, and females were larger than males in all study areas. Specimens from the island (central Sardinia) and from one mainland mountainous locality (Duchessa Mountains) were significantly smaller than those from all the other localities. Amphibians were the main prey for both sexes, but females ate more toads and fewer frogs or tadpoles than males; females also consumed more rodents than males. There was a strong effect of locality on diet composition i.e. newts/salamanders were found only in two montane areas; hylids were found only in the single island area; and rodents were commonly preyed upon only at a single mainland locality. Two lizard corpses (Podarcis muralis) were scavenged by grass snakes at a mainland locality. The presence of the piscivorous snake Natrix tessellata, a potential competitor for food, did not have any apparent effect on the food types eaten by grass snakes because grass snakes consumed fish when sympatric with N. tessellata, but not at other sites. The dietary variation exhibited by grass snakes suggests that, by shifting their diets to other prey, they might be able to persist in areas where their usual natural prey has declined drastically, but this remains to be demonstrated.

Keywords: COMPETITION, BODY SIZES, FOOD HABITS, COLUBRIDAE

pp. 231-243
Authors: Chen, Liqiao; Murphy, Robert W.; Lathrop, Amy; Ngo, Andre; Orlov, Nikolai L.; Ho, Cuc Thu & Somorjai, Ildiko L. M.

Abstract: The taxonomy of ranid frogs is in a state of chaos, and Asian ranids are no exception. We undertook an investigation of the phylogenetic relationships of most major groups of Asian ranids using mitochondrial DNA sequences from the 12S, tRNAVal and 16S genes. The resulting phylogenetic hypothesis had varying correspondence with the current taxonomy of the frogs at the subfamilial and generic levels. In order to maintain a taxonomy that reflects phylogenetic history, a number of taxonomic changes are proposed. Within subfamily Raninae, we recognize the genera Rana, Amolops, Hylarana, Odorrana and Nidirana. Recognition of Huia is not supported by our data and the recognition of Pseudorana is equivocal. Tribe Limnonectini is elevated to subfamily Limnonectinae and it contains Limnonectes, Hoplobatrachus and Nanorana. Membership in Genus Limnonectes is redefined. Recognition of genera Paa and Chaparana results in a paraphyletic taxonomy.

Keywords: RANIDAE, ANURA, PHYLOGENY, MTDNA, ASIA

pp. 245-255
Authors: Walsh, Patrick T. & Downie, J. Roger

Abstract: Growth rate strongly influences survival and reproductive success in anurans, particularly during larval and juvenile stages. In tadpoles the availability of shelter has been linked to increased growth rates, but work on recently metamorphosed anurans has been limited. Three species (Physalaemus pustulosus, Leptodactylus fuscus and Mannophryne trinitatis) were used to examine the effects that shelters have on growth rates and behaviour in the laboratory. Shelter availability had a strong effect on growth in M. trinitatis and a weaker effect on L. fuscus and P. pustulosus. Shelter provided advantages in the trade-off between predator avoidance and resource gathering and/or osmoregulatory benefits. Osmoregulatory benefits may have had the greater impact on growth rates for three reasons: (1) the ability to burrow in L. fuscus and P. pustulosus would more likely offset the osmoregulatory benefits of having shelters available, as individuals without shelters spent significantly more time burrowing; (2) individuals with shelter available were more active than those without, but the difference was not significant; and (3) the humidity under the shelters was significantly greater than within the rest of the tank. All frogs spent a large amount of time under shelters, if available. Regardless of the causes for any accelerated growth rate, shelters should therefore be provided in any terrarium for captive breeding colonies. The substrate choice of all three species reflected their natural habitat, with M. trinitatis (the stream frog) spending the majority of time in water and the toad-like P. pustulosus spending < 5% of its time in water. L. fuscus behaviour also reflected its natural habitat preferences. Thus, careful consideration of a species' natural history must be made when selecting the substrates to be used in terraria.

Keywords: DENDROBATIDS, LEPTODACTYLIDS, REFUGE USE, JUVENILE ANURANS, OSMOREGULATION

pp. 257-263
Authors: Márquez, Rafael; Penna, Mario; Marques, Paulo & do Amaral, José Pedro S.

Abstract: The variability of the advertisement calls of males from two Chilean populations of the leptodactylid frogs, Eupsophus calcaratus and E. roseus was studied and their calling behaviour further defined. Characteristic audio spectrograms and oscillograms for each species are presented. The spectral and temporal features of the calls were analysed, and intra-population and inter-specific differences in sound parameters were tested using correlation and discriminant function analysis. The calls of both species were tonal, had specific frequency modulation patterns (FM), and showed substantial inter-individual variation in several of their components. At least four discernible types of FM patterns were found in both species. Audio-spectrogram correlation and discriminant analysis showed that the quantitative characteristics of the calls of the species were clearly distinct; the most discriminating parameters were frequency, inter-call interval, and fundamental frequency.

Keywords: BEHAVIOUR, FREQUENCY MODULATION, LEPTODACTYLID, SOUND REPERTOIRE

pp. 265-272
Authors: Moreira, Pedro Lopes & Barata, Margarida

Abstract: Infertile and non-viable fertile eggs within a reptile clutch may decrease the incubation success of the remaining eggs, as (1) opportunistic pathogens may use the nutrient resources provided by dead eggs to colonize the clutch and spread to and kill viable eggs; and (2) odours released by spoilt eggs may attract predators to the clutch. These hypotheses were tested on the Iberian rock lizard (Lacerta monticola) by comparing the incubation success of fertile eggs between clutches composed solely of fertile eggs and clutches containing a small number of dead eggs. In a laboratory experiment, fungi (Fusarium sp. and Gliocladium sp.) colonized both infertile eggs and fertile eggs that died during incubation and thereafter spread to and killed adjacent eggs. In addition, offspring hatched earlier from fungal infected eggs than from non-infected eggs. The former were smaller and lighter than the latter, as they hatched before using the full egg yolk content. Results from a field experiment did not corroborate the fungal pathogenic effects observed in the laboratory nor did they confirm that clutches containing dead eggs suffer higher predation. Despite the inconclusive results regarding the role of fungal pathogens in nature, the present study indicates that this subject deserves further investigation in reptiles.

Keywords: EARLY HATCHING, EGG INFERTILITY, FUNGAL PATHOGEN, EGG VIABILITY

pp. 273-278
Authors: Della Rocca, Francesca; Vignoli, Leonardo & Bologna, Marco A.

Abstract: We studied the reproductive biology of the spectacled salamander, Salamandrina terdigidata, in Central Italy by daily sampling over three breeding seasons. Reproduction takes place annually, between February and May. Clutch size varies (1–65), and are usually placed by females on the underside of stones. The total number of eggs deposited varies yearly and is positively related to the period of preceding rainfall. Large females start breeding earlier and show stronger oviposition site fidelity than small ones. For oviposition females choose the portions of the stream that have the highest density of stones. The speed at which embryos develop increased over time, presumably under the influence of rising water temperature. Hatching success is negatively affected by aquatic drift, desiccation, predation by Trichoptera larvae and the absence of hiding sites.

Keywords: EGG PRODUCTION, SALAMANDER, ITALY, MICROHABITAT SELECTION

pp. 279-284
Authors: Prado, Cynthia P. A.; Toledo, Luís Felipe; Zina, Juliana & Haddad, Célio F. B.

Abstract: The South American pepper frog, Leptodactylus labyrinthicus, is a large species that lays eggs in foam nests in holes dug out of the banks of different bodies of water. Recently, it was reported that only 6–10% of eggs are fertilized in foam nests of L. labyrinthicus and the remaining unfertilized eggs are consumed by the tadpoles inside the nest. Here we tested experimentally the influence of the ingestion of trophic eggs on the survivorship and growth of L. labyrinthicus tadpoles. Tadpoles fed on trophic eggs and subsequently fed on dry fish food grew larger than those fed only on dry fish food, and this suggests that the ingestion of trophic eggs is an adaptation to improve tadpole growth. The ingestion of trophic eggs also seems to be important for the maintenance of tadpoles in environments with unpredictable rainfall, as they were able to survive for about 70 days feeding only on these trophic eggs and one tadpole managed to complete metamorphosis feeding on trophic eggs only. Details of the spawning behaviour observed in the field, occurrence of multiple mating, and predation on eggs by terrestrial invertebrates and vertebrates are also reported.

Keywords: MULTIPLE MATING, REPRODUCTION, SPAWNING BEHAVIOUR, EGG PREDATION, FROG

pp. 285-290
Authors: Anadón, J. D.; Giménez, A.; Pérez, I.; Martínez, M. & Esteve, M. A.

Abstract: We searched for patterns in the local abundance of Testudo graeca graeca with respect to relief characteristics in south-east Spain. The detection of tortoises during linear transects, in sampling plots and through fortuitous observations was used to examine distribution in relation to aspect and to topographic position at two different local scales. Both aspect and run-off gradients produced spatial patterns in the local abundance of T. g. graeca. These patterns are discussed with regard to the key conditions and resources for the species (solar radiation, food and nesting sites). At both scales tortoises were more abundant on north-west facing slopes, where solar radiation levels are assumed to be moderate to high, and where there are probably plenty of food resources. The apparent avoidance of north-east facing slopes, despite an abundance of food, suggests that tortoises may not be able to thermoregulate adequately in these areas and that thermoregulation may be the most important requirement for the species. Valley bottoms, mainly occupied by non-irrigated crops, were also selected. Therefore, our results suggest that there is a spatially aggregated population structure at a local scale that is caused by factors associated with relief.

Keywords: TOPOGRAPHY, ECOLOGY, ASPECT GRADIENT, RUN-OFF GRADIENT, CHELONIA

pp. 291-294
Authors: Measey, G. John & Royero, Ramiro

Abstract: Invasive populations of anurans contribute to global amphibian declines, and many instances involve pipid frogs. Here we report on an invasive population of Pipa parva in Carabobo State, and a native population in Zulia State, Venezuela. The frogs were found in high densities in a fish farm near Lake Valencia, and had a diet of benthic invertebrates. Invasive P. parva were large compared to those described in previous reports (mean snout-vent length: 37.34±0.73 mm), but the native population was found to be significantly longer (mean snout-vent length: 44.08±1.34 mm). Colonisation by terrestrial movement and potential impact of this invasive species are discussed.

Keywords: INVASIVE AMPHIBIANS, MORPHOLOGY, SOUTH AMERICA, DIET

pp. 295-298
Authors: Díaz, José A.; Cabezas-Díaz, Sara & Salvador, Alfredo

Abstract: We studied the thermal consequences of microhabitat selection by Psammodromus algirus lizards by combining data on the frequency of use and relative availability of three different types of microhabitats, with information about the environmental operative temperatures, and their deviations from the lizards' selected thermal range, available in these microhabitats. In both seasons, lizards preferred holm oak shrubs and avoided rockrose shrubs and open areas. However, the thermal suitability of holm oaks was highest in July but lowest in May. We suggest that microhabitat preferences were more related to other aspects of lizard ecology (e.g. antipredator behaviour) than to thermal requirements.

Keywords: PREDATION RISK, LIZARD, THERMOREGULATION, OPERATIVE TEMPERATURES