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The effect of funnel trap type and size of pitfall trap on trap success: implications for ecological field studies
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Funnel and pitfall traps that are set in association with drift fences are powerful tools for field herpetologists. Innovations in trapping techniques continue to improve capture rates, portability and affordability of trap materials, and to decrease construction and installation time. In this paper we test a new design for funnel traps and test the effect of pitfall trap size on trap success. Our new funnel trap design was significantly easier and quicker to construct, but captured fewer specimens than the traditional design. There was no significant difference in the capture rates of the two sizes of pitfall trap that we tested. This finding was confirmed by a second, more extensive field survey. The implications of trap efficacy on ecological investigations are discussed.
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Group location in the group-living lizard, Cordylus cataphractus: the significance of occupancy and a group signal
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Chemical cues in the form of glandular secretions may play an important role in the location and selection of shelters in lizards. The present study investigated the possible existence and significance of a composite group signal in the group-living cordylid, Cordylus cataphractus. Cordylus cataphractus is very sluggish and probably extremely vulnerable during periods away from the crevice. A group signal would aid dispersing or lost individuals in locating groups of conspecifics in the shortest possible time. Choice experiments to determine shelter selection were conducted in the laboratory as well as in the field, in order to test specific predictions following from the group signal hypothesis. In the laboratory, there was a statistically significant preference for shelters marked with conspecific glandular secretions over unmarked shelters. In the field, individuals strongly avoided crevices occupied by conspecifics. It seems likely that a composite group signal does exist, and that such a signal may be used to locate groups of conspecifics. Whether an individual will actually join a group seems to be determined by the interaction of a number of complex factors.
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Spatial characterization of a foraging area for immature hawksbill turtles (Eretmochelys imbricata) in Yucatan, Mexico
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The submarine habitats in the Rio Lagartos Sea Turtle Sanctuary, Mexico, are an important feeding and development area for juvenile Hawksbill turtles (Eretmochelys imbricata). The characterization of these critical habitats is an important and urgent issue to attend for the conservation of this species in Mexico. The objective of this study is to identify, locate and describe the marine benthic habitats in this area, and explain the distribution of the juvenile Hawksbill turtles in the study area. We used submarine techniques such as videotransects and spot checks to characterize the bottom types in the area, and geostatistic techniques to elaborate thematic maps of the different benthic components, integrating all of them into a GIS. We obtained the bottom type map with eight submarine habitats at different depth ranges. We found juvenile Hawksbill turtles distributed mainly on hard bottom sites covered by octocorals, such as Pseudopterogorgia, and sponges of the genera Chondrilla and Spheciospongia. We estimated habitat ranges for the captured turtles and the bottom types occupied by them, then we calculated the distribution densities of juvenile Hawksbill turtles by bottom type. We concluded that the combination of spatial techniques and multivariate statistics is efficient for mapping the marine bottom types in the area, and recommend the generation of specific conservation strategies to protect this area because of the natural marine resources and process ocurring in it.
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Size-dependent heating rates determine the spatial and temporal distribution of small-bodied lizards
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The rate of heat exchange with the environment is of obvious importance in determining the time budget of behavioural thermoregulation in ectotherms. In small reptiles, heating rate depends mainly on their physical characteristics. We analysed the effect of body size, and the possible joint effects originating from shape and colour differences on heating rate in three small-bodied (0.15-20 g) sympatric lizard species. Heating rate was strongly influenced by body size, while no joint effects with the two other factors were detected. We found that the increase in heating rate with decreasing body size accelerated dramatically below a body weight of 2-3 g. We also analysed associations between body size, seasonal activity patterns and thermal characteristics of the sites where lizards were encountered in the field. Differently sized lizards occurred in thermally different sites and differed in their seasonal activity patterns, both within and among species. Smaller (<2-3 g) lizards occurred in cooler sites and exhibited very low activity during summer. Our results suggest that body size has a considerable influence on the spatial and temporal distribution of extremely small lizards in environments subject to a danger of overheating.
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Population genetics of the Amazonian tortoises, Chelonoidis denticulata and C. carbonaria, (Cryptodira: Testudinidae) in an area of sympatry
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We conducted a population genetic analysis of the two Amazonian tortoises, Chelonoidis denticulata (n = 40) and Chelonoidis carbonaria (n = 39) in a region of sympatry within the Xingú River basin. High levels of gene flow among sampled localities indicated lack of population structure for both species. Genetic parameters indicated a moderate level of genetic diversity in C. denticulata and neutrality tests suggested that populations of this species were in demographic equilibrium with respect to mitochondrial DNA. On the other hand, C. carbonaria presented low levels of genetic diversity and a signal of population expansion. Most records of C. denticulata are from areas of humid forest while those for C. carbonaria are from areas of semi-deciduous forests and transitional areas between humid and semi-deciduous forests. Therefore, the demographic expansion observed in C. carbonaria population could reflect an increase in the availability of suitable habitats for this species due to anthropogenic or natural processes. Additionally, we observed haplotype sharing between these two tortoise species indicating hybridization or incomplete lineage sorting.
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Techniques for tracking amphibians: The effects of tag attachment, and harmonic direction finding versus radio telemetry
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To gain information on the microhabitat use, home range and movement of a species, it is often necessary to remotely track individuals in the field. Radio telemetry is commonly used to track amphibians, but can only be used on relatively large individuals. Harmonic direction finding can be used to track smaller animals, but its effectiveness has not been fully evaluated. Tag attachment can alter the behaviour of amphibians, suggesting that data obtained using either technique may be unreliable. We investigated the effects of external tag attachment on behaviour in the laboratory by observing 12 frogs for five nights before and five nights after tag attachment, allowing one night to recover from handling. Tag attachment did not affect distance moved or number of times moved, indicating that the effects of tag attachment are unlikely to persist after the first night following attachment. We then compared harmonic direction finding and radio-telemetry using data collected in the field. We fitted rainforest stream frogs of three species with tags of either type, located them diurnally and nocturnally for approximately two weeks, and compared movement parameters between techniques. In the field, we obtained fewer fixes on frogs using harmonic direction finding, but measures of movement and habitat use did not differ significantly between techniques. Because radio telemetry makes it possible to locate animals more consistently, it should be preferred for animals large enough to carry radio tags. If harmonic direction finding is necessary, it can produce reliable data, particularly for relatively sedentary species.
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Effects of a paved road on mortality and mobility of red bellied toads (Melanophryniscus sp.) in Argentinean grasslands
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Melanophryniscus sp. is an endemic toad restricted to Sierra de la Ventana, in the Argentine Pampas. Part of its reproductive habitat is crossed by a paved road. We studied the effects of the road on the mortality and mobility of the toads. During the days following rain, we surveyed transects on both sides of the road, capturing, photographing and immediately releasing each toad. Population size in the area was estimated in 1074 individuals (871 to 1363, 95% CI) by means of mark-recapture analysis. We found fifteen individuals killed by vehicles in the 2003-04 and ten in the 2004-05 reproductive seasons. This mortality represents from 2.5 to 5.9% of the population annually, considering that 73% of the mortality period was sampled and a detection rate of dead frogs of 40%. Other factors associated to roadside habitat, such as rapid drying of roadside ditches, maintenance work, increased frequency of fire, pollution by gas, oil and fuel emissions and losses from vehicles, and poaching as pets by tourists, may also reduce the survival of the toads. We recorded capture sites and calculated the average distance between captures as 33.04 m for males and 22.50 m for females. Only two of the 76 observations of recaptured toads were made on the opposite side of the road. Roads can be considered as having a significant impact on this species by augmenting mortality, hindering the mobility of the species and increasing habitat isolation.
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Effect of cold temperature on the length of incubation of Chamaeleo chamaeleon
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Common chameleon eggs spend the first months of incubation at low temperatures. I incubated eggs of different clutches at 25°C in four treatments with respectively 0, 84, 119 and 149 days of initial cold period (at 14°C). Treatments with longer cold periods had longer total incubation but shorter periods of incubation at 25°C. Eggs which did not experience initial cold period showed low synchronization at hatching. Hatchling body mass and length were influenced by the length of the cold period. Hatchlings were largest and heaviest for cold periods of intermediate length which had similar duration than the cold period experienced by eggs in nature. These results suggest that the cold torpor period of Common chameleon embryos contributes to optimization of development and growth, and synchronizes hatching.
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An evaluation of the taxonomic validity of Testudo werneri
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The Egyptian tortoise Testudo kleinmanni was recently split into two species on the basis of apparent differences in shell morphology and markings. Testudo kleinmanni was restricted to areas west of the Nile river and a new form, T. werneri, was described which occurred east of the Nile river (Perälä, 2001). However, when the morphometric analysis on which this decision was based (Perälä, 2001) was adjusted to allow for experiment-wise Type I error, by using P-value corrections, the proportion of the 46 characters that differed significantly between the two populations fell from 36.9% to only 13% in males and from 39.1% to just 8.7% in females. We then conducted a new morphometric analysis using our own data set that showed minor significant variation in morphometric and plastron markings between populations. An analysis of mitochondrial DNA based on 393 base pairs of the 12S rRNA gene, also showed near uniformity of western and eastern populations. Genetic divergence was only 0.2%, with the only consistent difference being a single G – A substitution at position 205. Based on the revised interpretation of Perälä (2001) results, our morphometric analysis on our own data set, and the molecular evidence, the variation observed between populations is normal within a species and therefore T. werneri is not a distinct independent evolutionary lineage and should not be considered a separate species from T. kleinmanni.
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Flight initiation distance in relation to substratum type, sex, reproductive status and tail condition in two lacertids with contrasting habits
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Flight initiation distance in relation to substratum type, sex, reproductive status and tail condition was studied in two lacertid lizards with contrasting habits: the ground-dwelling common lizard Zootoca vivipara and the rupicolous Horvath's rock lizard Iberolacerta horvathi. These species were studied in sympatric populations in a mountain area in North-Eastern Italy, Tarvisio Forest. Mean escape distance was significantly higher in I. horvathi than in Z. vivipara. In both species there were significant differences between sexes, with males escaping at longer distances than females but there were no significant differences between adults and subadults. In both species there were no differences in escape distance of females in different reproductive states. In Z. vivipara specimens with broken tails escaped at a shorter distance than individuals with intact tails. Substratum type had a significant effect on escape distance in both species.
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Morph-specific immunity in male Podarcis muralis
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Permanent colour polymorphism in lizards is maintained by complex interactions between environmental pressures and physiological traits (such as immune responsiveness) that differ among morphs. In this study we investigated whether T-cell mediated immune response vary among male colour morphs in the trimorphic (white, yellow and red) common wall lizard, Podarcis muralis. We found that yellow males showed a lower immune response compared to both red and white males, whose responses were similar. Thus, immune responsiveness is morph-specific in male common wall lizards, suggesting that this physiological trait could play an important role in maintaining colour polymorphism in this species. Moreover, immune responsiveness significantly increased with increasing male size, irrespective of colour morph, indicating that it could be regarded as a condition-dependent trait.
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Elevated tongue-flicking rate to cricket surface chemicals by the arthropodivorous rough green snake Opheodrys aestivus
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The rough green snake Opheodrys aestivus is a dietary specialist on insects and other arthropods. In a laboratory experiment, I tested chemosensory responses to chemical cues from several taxa palatable to other snakes and two control stimuli presented on cotton swabs. The snakes tongue-flicked at significantly higher rates in response to cues from crickets than from any of the other stimuli, and none of the other potential prey types elicited more tongue-flicks than cologne, the control for response to an odorous substance irrelevant to feeding. These findings are consistent with existing data for a few other species of snakes that are prey specialists, suggesting that correlated evolution may occur between diet specialization and chemosensory responsiveness to cues from the specialized prey. Tests of additional species of prey specialists are needed to establish whether this hypothesis is correct.
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Mitochondrial phylogeography of European pond turtles (Emys orbicularis, Emys trinacris) – an update
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Based on more than 1100 samples of Emys orbicularis and E. trinacris, data on mtDNA diversity and distribution of haplotypes are provided, including for the first time data for Armenia, Georgia, Iran, and the Volga, Ural and Turgay River Basins of Russia and Kazakhstan. Eight mitochondrial lineages comprising 51 individual haplotypes occur in E. orbicularis, a ninth lineage with five haplotypes corresponds to E. trinacris. A high diversity of distinct mtDNA lineages and haplotypes occurs in the south, in the regions where putative glacial refuges were located. More northerly parts of Europe and adjacent Asia, which were recolonized by E. orbicularis in the Holocene, display distinctly less variation; most refuges did not contribute to northern recolonizations. Also in certain southern European lineages a decrease of haplotype diversity is observed with increasing latitude, suggestive of Holocene range expansions on a smaller scale.
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Reproductive biology and sexual dimorphism of a high-altitude population of the viviparous lizard Phymaturus punae from the Andes in Argentina
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Phymaturus punae is a viviparous lizard endemic to the Provincial Reserve San Guillermo, San Juan (Argentina). We present the first life history data of P. punae, belonging to an interesting genus adapted to cold climates. Females reach sexual maturity at 80.6 mm, and males at 84.4 mm snout-vent length. There is sexual dimorphism represented by larger and more robust males, but females show a wider body and a proportionally greater interlimb length than males. In males, spermatozoa become abundant in both testes and epididymi in mid-summer. Vitellogenic and pregnant females occurred simultaneously in late spring and mid-summer indicating a biennial reproductive cycle.
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A comparison of the success of artificial cover types for capturing amphibians and reptiles
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The use of artificial cover objects, or cover boards, is a common method for collecting and surveying amphibians and reptiles. Cover objects, plywood and corrugated tin, were placed in open and closed canopy sites in an east Texas floodplain. The assemblages captured were compared between tin and wood. The odds of capture were compared between the two types as well as the odds of capture in open and closed canopy sites. The combined amphibian and reptile assemblages differed between tin and plywood. The odds of capturing an amphibian or reptile under corrugated tin were slightly higher (1.2:1) when compared to plywood. Further, the odds of capture were less likely in closed canopy sites (0.89) than open canopy sites.
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Ultraviolet reflectance of male nuptial colouration in sand lizards (Lacerta agilis) from the Pyrenees
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The evolutionary significance of lacertid colourations is relatively unexplored. However, several studies have demonstrated signalling by means of bright green colouration in Swedish Lacerta agilis males during the breeding season. Unfortunately, most of these studies have been based on human colour perception that differs in several ways from that of lizard. An important difference between human and lizard colour vision is the presence of an ultraviolet (UV) sensitive cone in lizards. The available evidence suggests that male sand lizards colorations do not reflect UV wavelengths, at least in Swedish populations. However, this study, based on objective (spectrophotometric) measures of Pyrenean L. agilis, revealed a secondary reflectance peak in the UV in male green colouration. This secondary peak increases sexual dichromatism and male conspicuousness. Moreover, it could have a social signalling function as do similar UV reflecting patches in other lizard species.
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The role of vegetation in microhabitat selection of syntopic lizards, Phrynocephalus persicus, Eremias pleskei, and Eremias strauchi from Armenia
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Composition and density of vegetation are important habitat quality indicators for reptiles. The goal of this note was to determine dominant plant species, optimal size and density in habitats of syntopic lizards in the Goravan Sands Sanctuary. The role of vegetation variables was considered in relation to differences in thermoregulation of syntopic Phrynocephalus persicus, Eremias pleskei, and Eremias strauchi. Microhabitats of P. persicus differed from that of E. pleskei and of E. strauchi by a relatively frequent encounter of the plant Achillea tenuifolia, which is considered as potential habitat quality indicator. Phrynocephalus persicus generally used microhabitats with sparser vegetation. It is supposed that the excessive growth of shading vegetation can have a more negative impact on P. persicus than on E. pleskei.
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Advances in methodologies of sexing and marking less dimorphic gekkonid lizards: the study case of the Moorish gecko, Tarentola mauritanica
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Novelties in systems of sexing and marking less dimorphic species of gekkonid lizards are described and first results are presented on the Moorish gecko, Tarentola mauritanica, used as target and model species. Inspection of cloacal opening and tail basis to detect hemipenes has been done with a small probe and with laser light. Behavioural response to tail basis touch was typical of adult males. Permanent marking has been performed along with the removal of some subdigital scales. Sexing was suitable and feasible on all individuals larger than 45 mm snout to vent length.
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