The Herpetological Journal

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Authors: Sinsch, Ulrich

Abstract: A long-standing challenge for amphibian population ecologists is the reliable estimation of age in individuals without known recapture history. The development and widespread application of skeletochronology seems to have solved the issue, although studies evaluating the precision and reliability of age estimates are rare and controversial. Skeletochronology attempts to relate the number of dense hematoxylinophilic narrow growth marks (Lines of Arrested Growth, LAGs) separated by faintly stained broad growth zones in the round bones of Anura and Caudata with age. In this review, I briefly summarise the laboratory procedures to obtain informative histological cross sections, and the interpretation of growth marks becoming visible through staining. I discuss the precision and constraints of skeletochronological age estimation by evaluating evidence derived from individuals with known age. Individuals of up to eight years of age are correctly aged by LAG-counting, whereas the lifespan of older individuals is systematically underestimated, due to the increasing rapprochement of LAGs at the periphery of bones. A case study on the latitudinal and altitudinal variation of demographic life-history traits in natterjack toads illustrates the utility of skeletochronology to assess plasticity of age distributions in response to climate variation. Finally, I provide perspectives for future research to which skeletochronology may contribute valuable information.

Keywords: LIFE HISTORY, AGE AT MATURITY, LONGEVITY, SKELETOCHRONOLOGY, GROWTH PATTERN, LARGE-SCALE VARIATION AMONG AND WITHIN SPECIES

pp. 15-19
Authors: Meek, Roger

Abstract: Reptiles are commonly impacted by roads. Mortalities from road traffic are best documented in snakes, but information on roadside habitat features where snakes cross or attempt to cross roads are less frequently reported. If roadside habitat is important, then snakes should be selective of where they make a crossing. To test this hypothesis, roadside habitats where snakes crossed or attempted to cross roads were compared with roadside habitat availability in a study site in western France. Vipera aspis, Hierophis viridiflavus, Natrix natrix and N. maura crossed roads more often than expected next to woodland and low density urban areas. Road crossing locations were also compared with snake abundance in roadside habitat. Frequencies of crossings were higher than expected in woodland and high-density urban areas in relation to their abundance in these habitats. However, abundance related road crossings were less frequent than expected near hedgerows. This suggests that snakes were reluctant to emerge from a habitat pathway that connects prime habitat patches in a fragmented landscape.

Keywords: ROAD CROSSINGS, WESTERN FRANCE, MORTALITIES, ROADSIDE SNAKE ABUNDANCE, SNAKES, ROADSIDE HABITAT

pp. 21-26
Authors: Michaels, Christopher J. & Preziosi, Richard F.

Abstract: The larvae of many amphibians are highly sensitive to environmental conditions. Tadpoles can adjust their development in response to stressors, but this may come at a cost in terms of fitness. The captive environment may be the source of stressors and may therefore influence the fitness of larval amphibians reared for conservation. We investigated the effects of shelter provision on fitness in captive tadpoles of the red-eyed treefrog (Agalychnis callidryas). Larvae maintained with shelter metamorphosed significantly larger and later than animals maintained with either no shelter or with shade only. Behavioural data suggest that the positive effect of shelter provision on fitness may be due to a reduced stress response; animals showed more extreme anti-predator behaviour when housed with no shelter and intermediate responses when housed with shade alone. Our data show that the design of captive enclosures can influence the fitness of captive amphibians.

Keywords: PHENOTYPIC PLASTICITY, SHELTER, FITNESS, EX SITU CONSERVATION, HUSBANDRY, ENRICHMENT, TADPOLE, AMPHIBIAN

pp. 27-39
Authors: Gomes, Fabíola Fonseca Almeida; Caldas, Francis Luiz Santos; dos Santos, Rafael Alves; da Silva, Bruno Duarte; Santana, Daniel Oliveira; Rocha, Stéphanie Menezes; Ferreira, Anthony Santana & Faria, Renato Gomes

Abstract: This study examines how two species of diurnal lizards (Tropidurus semitaeniatus and T. hispidus, Tropiduridae) use spatial, trophic and temporal resources in the Conservation Unit of Monumento Natural Grota do Angico, Poço Redondo, Sergipe (Brazil). Both species were mostly active during sunny days, with a reduction in activity during the hottest hours, and showed a preference for rocks, using rock crevices as main shelter. Tropidurus hispidus is the larger species as measured with SVL, and the species did not markedly differ in overall body shape. Both species mostly predated ants, insect larvae and termites. The head morphologies of T. semitaeniatus and T. hispidus are better adapted for the ingestion of larger and longer prey, respectively. Tropidurus semitaeniatus individuals modified their food intake during periods of higher rainfall, possibly to avoid competition with T. hispidus. Despite the high overlap in the use of space, time and diet, the coexistence of the two species is facilitated through resources strategies that minimise the negative effects of competition.

Keywords: SYMPATRY, ECOLOGY, LIZARDS, RESOURCE PARTITIONING, DRY FOREST

pp. 41-48
Authors: Cruz-Elizalde, Raciel; Ramírez-Bautista, Aurelio; Wilson, Larry David & Hernández-Salinas, Uriel

Abstract: This study assesses the effectiveness of three Protected Natural Areas (PAs) in central Mexico (Parque Nacional El Chico, PNCH, Parque Nacional Los Mármoles, PNLM, and Reserva de La Biosfera Barranca de Metztitlán, RBBM), for the conservation of amphibians and reptiles. We also evaluate the conservation status of the concerned species assigned by the Mexican list for plants and animals, IUCN, as well as the species' Environmental Vulnerability Score. PNLM shows the highest richness and taxonomic diversity of both groups compared to those of PNCH and RBBM. We recorded a high number of endemic species, a high percentage of species (up to 88%) under risk categories, and a threat by environmental vulnerability for all species. We suggest that such analyses need to be expanded across a higher number of PAs in Mexico to determine their effectiveness in the protecting species of amphibians and reptiles and other biological groups.

Keywords: HIDALGO, CONSERVATION, NATURAL AREAS, EFFECTIVENESS, AMPHIBIANS, REPTILES

pp. 49-53
Authors: Vicente, Natalin & Halloy, Monique

Abstract: Visual communication is important in many lizard species. One conspicuous visual signal is the headbob display, which consists of a stereotyped up and down movement of the head and/or torso. We analysed male headbob displays in the neotropical lizard, Liolaemus pacha, in its natural environment. Our objectives were to describe and analyse the structure and form of these headbob displays and to relate these to two social contexts: male without an apparent receiver (MA context) and male responding to another male (MM context). We measured duration of each headbob bout, its maximum amplitude, duration of intervals, number of headbob bouts and presence or absence of three modifiers (gular inflation, back arching and lateral compression). We found two types of triple headbob displays, corresponding to what has been previously reported as the challenge headbob and the broadcast headbob display. Duration and maximum amplitude were significantly greater in headbob displays in the MM context compared to the MA context. We did not observe modifiers when a male was in the MA context but there was at least one modifier present in the MM context.

Keywords: NEOTROPICAL LIZARDS, LIOLAEMUS PACHA, VISUAL DISPLAYS, HEADBOB DISPLAY

pp. 55-59
Authors: Solís, Rigoberto; Penna, Mario; De la Riva, Ignacio; Fisher, Matthew C. & Bosch, Jaime

Abstract: The chytrid fungus Batrachochytrium dendrobatidis (Bd) is a causal agent of infectious disease and decline of anuran populations inhabiting mountain systems in Central and South America. The chytrid is believed to have spread from Ecuador southward, as has recently been detected in the Andean cordilleras of Peru, Bolivia and Argentina. However, since the status of anuran populations from the Chilean Altiplano is unknown, we undertook an intensive survey of amphibian populations inhabiting high elevations in northern Chile. Bd-infected individuals were detected only in the northernmost localities sampled suggesting an ongoing process of Bd spread southward along the Andes.

Keywords: ANURAN, BATRACHOCHYTRIUM DENDROBATIDIS, CHILE, ANDES, PREVALENCE, HIGHLAND

pp. 61-64
Authors: Penske, Sandra; Gvoždík, Václav; Menegon, Michele; Loader, Simon P. & Müller, Hendrik

Abstract: The tadpole of Leptopelis cf. grandiceps is described from the Uluguru Mountains of Tanzania. The tadpole resembles other Leptopelis tadpoles but differs from known East African Leptopelis tadpoles in having a divided first row (P1) of infralabial keratodonts and in having more and longer oral papillae. There are furthermore pronounced differences in oral apparatus morphology between tadpoles of L. cf. grandiceps previously described from the Ukaguru Mountains and the material described here, which might indicate that the populations are in fact separate species. Tadpole morphology can provide additional characters that can contribute to taxonomic assessments and revisions.

Keywords: EASTERN ARC MOUNTAINS, TAXONOMY, BARCODING