Thermal ecology and activity patterns of the lizard community of the Restinga of Jurubatiba, Macaé, RJ

Use of microhabitat and activity patterns of two lizard species from a seasonal dry forest in northern Colombia

In this work, the microhabitat use and activity patterns of two lizard species with sympatric distribution were evaluated in a dry forest fragment within the department of Sucre, northern Colombia. Data was collected in May, June, September and October of 2017, using the active search method limited by time (7:00 and 19:00 hours). Substrates used, spatial distribution and time of capture were recorded for individuals of the species Loxopholis rugiceps (Cope 1869) and Lepidoblepharis sanctaemartae (Ruthven 1916). Complementarily, environmental and physical parameters were recorded, which allowed us to characterise the microhabitats of the species. A total of 276 lizards were recorded, 177 belonging to the species Loxopholis rugiceps and 99 to Lepidoblepharis sanctaemartae. The results showed similar resource use by the two species for the spatial dimension, with both exploiting different terrestrial elements mainly from the interior forest, followed by the riverbed stream and forest edge. Differences were found in the daily activity patterns between species, with individuals of L. sanctaemartae more frequently recorded in the morning hours and L. rugiceps in the afternoon hours. The activity patterns did not differ by age groups: juveniles and adults. Both species were more frequently found in the litter substrate within the forest, followed by rocks and bare ground. Our results indicate that both species are tolerant to matrix conditions, however, they require internal forest conditions to exploit food resources and refuge.

The lizard that never sleeps: activity of the pampa marked gecko Homonota uruguayensis

ABSTRACT It is generally assumed that lizards are active whenever climatic conditions are favorable. Homonota uruguayensis (Vaz-Ferreira & Sierra de Soriano, 1961) is the only native gecko - and nocturnal lizard - living in the northern Pampa biome, and its ecology is poorly known. This study aimed at describing this species’ pattern of daily and annual activity and its relation with environmental temperatures. The study was conducted in the extreme south of Brazil (Rosário do Sul, State of Rio Grande do Sul), between May 2010 and January 2011 at a rocky outcrop located in the Pampa biome. The study was carried out in a total of four seasonal field trips, totalizing 1185 hours of field work. The data were collected, both during the day and the night in 6-hour shifts (duration of the sampling period). The area was randomly covered at each shift to record activity and microhabitat use by the lizards. In total 1541 specimens were recorded throughout the study. Homonota uruguayensis showed diurnal and nocturnal activity in the four seasons, with periods of daily activity varying significantly between all seasons in a cyclic and multimodal pattern, with no significant relation with environmental temperatures. There was no difference in activity related to sex and age classes. Most active lizards were found when air temperatures ranged from 14 °C to 32.9 °C (82% of active lizards) and substrate temperatures ranged from 10 °C to 32.9 °C (87% of active lizards).

Thermal ecology and microhabitat use of an arboreal lizard in two different Pantanal wetland phytophysionomies (Brazil)

Temperature is one of the main environmental variables shaping the evolution and biology of terrestrial ectotherms. The Pantanal is the largest continuous wetland in the World. However, a lack of knowlegde still exists on the thermal ecology of terrestrial ectothems from this wetland. In this context, the thermal ecology of the lizard Tropidurus lagunablanca Carvalho, 2016 (Squamata, Tropiduridae) was investigated in the Brazilian Pantanal. The thermal ecology and microhabitat use of lizards from a riparian forest was compared to lizards from a park savanna. At both studied areas, air and body temperatures of lizards did not differ between sexes. Mean T. lagunablanca body temperatures were higher at the savanna compared to the forest, while air temperatures were similar in both habitats. The main substrates were tree trunks, with a frequency of approximately 90% of the observations. Lizards from the savanna used higher perches than those from the forest despite -in average- trees were higher at the forest. Lizard sun and shade exposure was similar for both areas. Lizards from both habitats showed similar strong linear relationships between body and air temperatures. However, lizard behaviour of using tree trunk perches differently under different sunlight situations suggests that these lizards actively thermoregulate. Further research on the thermoregulation abilities of this species, with a null hypotesis and behavioral observations will shed light on lizard thermal biology. Studies on the ecophysiological aspects of these lizards should be a priority to understand how they will react to climate change and which conservation measures will be more effective concerning their preservation.

To warm on the rocks, to cool in the wind: Thermal relations of a small-sized lizard from a mountain environment

Rising temperatures accompanying global climate change are expected to affect mountain lizards. Therefore, basic information on how these ectotherms deal with their thermal environment is important for further management. We conducted a field study to evaluate how body temperature of the small-sized mountain lizard Eurolophosaurus nanuzae relates to the thermal environment. After capture, the body temperature of the lizards was measured immediately, quickly followed by the substrate and air temperatures, wind intensity, and solar radiation at the capture locations. Linear relationships showed that the body temperature of individuals was positively related to rocky substrate temperatures but negatively related to wind speed. However, air temperature and solar radiation were unrelated to body temperature. Although the substrate is an important heat source for E. nanuzae, in an open environment it can reach temperatures up to 10 °C above the maximum body temperatures of lizards, and can thus be a low-quality thermal substrate. However, individuals seemed to use wind as a cooling source to counterbalance the risks of overheating from high substrate temperatures. As the montane environment that E. nanuzae inhabits seems to have hotter temperatures than those preferred by the species, lizards should benefit from the cooling winds to keep their body temperature at appropriate levels. Different to previous studies that evaluated wind effects on body temperatures of lizards, our results showed that winds seemed to promote thermoregulation for E. nanuzae.

Body orientation for thermoregulation and daily activity cycle of Mabuya macrorhyncha (Squamata: Scincidae)

We investigated the daily activity and thermoregulatory body orientation of Mabuya macrorhyncha (Hoge, 1947), a lizard species that occurs in the Brazilian Atlantic Forest. We conducted this investigation in a sandy coastal dune remnant (“restinga” ecosystem) in Grussaí, state of Rio de Janeiro, Brazil, during the summer. The daily activity cycle of the lizards started around 6:00 am and ended before 7:00 pm. This is longer than observed in other populations of M. macrorhyncha (approximately 7:00 am to 5:00 pm). The activity cycle of the lizards was bimodal, with the first peak between 6:00 and 11:00 am and the second from 2:00 to 7:00 pm. This contrasts with observations on other populations of this species, which revealed an unimodal pattern. The mean body temperature of M. macrorhyncha in Grussaí was 34.2 ± 1.5 °C, which was comparatively higher than observed in other populations of the species. The differences in the daily activity and of body temperature of these lizards between our study and previous studies on this species may reflect environmental thermal conditions. The mean air and mean substrate temperatures when individuals were active were 27.8 and 30.5 °C respectively. Lizard orientation was significantly correlated with the direction of the solar incidence, suggesting that solar radiation, and particularly behavioral adjustments that maximize exposure to the sun, are important for the thermoregulation of M. macrorhyncha. Circular structures at the site, such as bromeliads, offer microhabitats with different orientations to the sunlight, favoring lizard thermoregulatory behaviors.

Nematode infection patterns in a Neotropical lizard species from an insular mountain habitat in Brazil

Neotropical lizards are known to harbour rich nematode parasite faunas; however, knowledge of the diversity and patterns of infection are still lacking for many species. This is true for the genus Tropidurus, in which data on patterns of parasitism are known for only approximately 11 of its 30 species. We show that the nematode fauna associated with a population of Tropidurus montanus is composed of three species of host-generalist parasites with high overall prevalence. Male and female lizards did not differ in infection pattern and there was no relationship between host body size and intensity of infection for the most prevalent parasite species. Nevertheless, overall prevalence changed seasonally, with a higher proportion of parasitized individuals being found in the dry period than in the rainy period. We discuss our findings in the context of diet patterns of T. montanus, which we suggest may explain the similarities in prevalence and intensity of infection between the sexes. In addition, seasonal changes in diet are considered to be related to the observed differences in prevalence between dry and rainy periods.

Lizard assemblage from a sand dune habitat from southeastern Brazil: a niche overlap analysis

ABSTRACT Communities are structured by interactions of historical and ecological factors, which influence the use of different resources in time and space. We acquired data on time of activity, microhabitat use and diet of a lizard assemblage from a sand dune habitat in a coastal area, southeastern Brazil (Restinga de Jurubatiba). We analyzed the data of niche overlap among species in these three axes (temporal, spatial and trophic) using null models. We found a significant overlap within the trophic niche, whereas the overlap for the other axes did not differ from the expected. Based on this result, we discuss the factors acting on the structure of the local lizard community.

Occurrence and distribution of the exotic lizard Hemidactylus mabouia Moreau de Jonnès, 1818 in Ilha Grande, RJ, Brazil

The gekkonid lizard Hemidactylus mabouia is an exotic species in Brazil and is found in different ecosystems. This species was recorded at Ilha Grande, RJ, one of the largest insular remains of the Atlantic Rainforest in Brazil. In this study, the occurrence of H. mabouia was determined throughout the island, including the rain forest, restinga and anthropic environments. We used the active search method in points along 19 trails that surround Ilha Grande. At each regular interval of 100 m, we searched for the presence of H. mabouia. The species was recorded in a total of 100 points among the 719 sampled and, in all cases, the occurrence of the lizard corresponded to points located in anthropic or perianthropic areas. As most of Ilha Grande is covered by dense tropical rain forest, we believe this has restricted the invasion of H. mabouia in natural environments within the island.

Pampean lizard assemblage from subtropical Brazil: a temporal analysis

The increasing human occupation of natural environments is one of the greatest threats to biodiversity. To mitigate the negative anthropogenic effects, it is necessary to understand the characteristics of natural populations and the natural history of species. A study was conducted with an assemblage of lizards from a disturbed area of the Pampa biome, from February 2001 to January 2004. The assemblage showed a unimodal seasonal pattern, with the recruitment period occurring during the warmer months. The captures were seasonal for two of the three monitored years, and concentrated within warmer months. The minimum temperature explained the number of catches for the assemblage as a whole. However, when the species were analyzed individually, the temperature only explained the seasonal occurrence of Teius oculatus. The abundance of species was significantly different in the third year of study for Cercosaura schreibersii and Ophiodes striatus. This latter species was no longer registered in the study area from May 2003 until the end of the study. Therefore, O. striatus may be more sensitive to environmental changes, considering the events of change in vegetation during the study. With frequent and increasing environmental disturbances, it is necessary to take conservation measures and encourage the increase of knowledge on Pampean lizards.

Thermal biology, activity, and population parameters of Cnemidophorus vacariensis (Squamata, Teiidae), a lizard endemic to southern Brazil

We investigated the following aspects of the biology of a population of Cnemidophorus vacariensis Feltrim & Lema, 2000 during the four seasons: thermal biology, relationship with the thermal environment, daily and seasonal activity, population structure and growth rate. Cnemidophorus vacariensis is restricted to rocky outcrops of the "campos de cima da serra" grasslands on the Araucaria Plateau, southern Brazil, and is currently listed as regionally and nationally threatened with extinction. Data were collected from October 2004 through September 2007 in the state of Rio Grande do Sul. Sampling was conducted randomly from 08:00 a.m. to 6:00 p.m. The capture-mark-recapture method was employed. The lizards were captured by hand, and their cloacal temperature, sex, snout-ventral length (SVL), mass, and the temperature of their microhabitat (substrate temperature and air temperature) were recorded. Individuals were then marked by toe-clipping and released at the site of capture. Body temperatures were obtained for 175 individuals, activity data for 96 individuals, and data on population structure and growth for 59 individuals. All data were obtained monthly, at different times of the day. Cnemidophorus vacariensis average body temperature was 23.84ºC, ranging between 9.6 and 38.2ºC. Temperatures ranged between 21 and 29ºC. The correlation between external heat sources, substrate and air were positive and significant and there was a greater correlation between lizard's temperature and the temperature of the substrate (tigmothermic species). The relatively low body temperatures of individuals are associated with the climate of their environment (altitude up to 1,400 m), with large variations in temperature throughout the day and the year, and low temperatures in winter. The average body temperature observed for C. vacariensis was low when compared with that of phylogenetically related species, suggesting that the thermal biology of this species reflects adaptations to the temperate region where it lives. The monthly rates of activity of lizards were related to monthly variations in the ambient temperatures. Our data suggest that the daily and seasonal activity of C. vacariensis result from the interaction between two factors: changes in the environment temperature and the relationship between individuals and their thermal environment. The population structure of C. vacariensis varied throughout the study period, with maximum biomass in January and maximum density in February (recruitment period). The sex ratio diverged from the expected 1:1. The growth analysis showed a negative relationship between the growth rate of individuals and the SVL, revealing that young individuals grow faster than adults, a typical pattern for short-lived species. The population studied showed a seasonal and cyclical variation associated with the reproductive cycle. The life strategy of C. vacariensis seems to include adaptations to the seasonal variations in temperature, typical of its environment.

Daily activity and microhabitat use of sympatric lizards from Serra do Cipó, southeastern Brazil

We studied the influence of seasonality on the daily activity pattern and microhabitat use of three sympatric lizard species, Cnemidophorus ocellifer Spix, 1825 (Teiidae), Tropidurus montanus Rodrigues, 1987 and Eurolophosaurus nanuzae (Rodrigues, 1981) (Tropiduridae), in an area of campos rupestres (rocky fields) habitat in state of Minas Gerais, Brazil. Cnemidophorus ocellifer exhibited low density and activity concentrated within the hottest hours of the day, and was observed mainly on shaded rocks. Tropidurus montanus and E. nanuzae had similar activity patterns that did not vary between seasons. Activity of T. montanus was related to environmental temperatures. However, we did not find such relationships for E. nanuzae during the dry season. Both T. montanus and E. nanuzae were sighted mainly on exposed rocks. Extension of activity varied between seasons, shorter for C. ocellifer and longer for T. montanus and E. nanuzae during the rainy season.

História natural de Tropidurus oreadicus em uma área de cerrado rupestre do Brasil Central

Aspectos ecológicos e da biologia reprodutiva de Tropidurus oreadicus foram investigados em uma área de cerrado rupestre do Brasil Central. Foram estudados a morfometria, o uso do microhábitat, o padrão de atividade, a dieta e características da biologia reprodutiva de T. oreadicus em Cocalzinho - GO, de abril a setembro/2003. São animais sexualmente dimórficos, com os machos adultos maiores que as fêmeas. O microhábitat preferencial utilizado pela espécie foi a superfície das rochas (hábito saxícola). A espécie mostrou padrão de atividade unimodal. Foram frequentemente observados parados e expostos ao sol entre 9:00 e 10:59 horas. A alimentação desta população de T. oreadicus é baseada em formigas, larvas de inseto e besouros. Além disso, apresentaram mudanças ontogenéticas e diferenças intersexuais na dieta. Provavelmente essas diferenças estejam associadas à alocação diferenciada dos recursos para o crescimento ou produção dos gametas. A reprodução é provavelmente sazonal ocorrendo principalmente nos meses de maior pluviosidade.

Observations on the natural history of the lizard Mabuya macrorhyncha Hoge (Scincidae) in Queimada Grande Island, São Paulo, Brazil

Data are presented on the on diet, thermal biology, microhabitat use, reproduction and helminth infection parameters of a population of Mabuya macrorhyncha hoge, 1946 inhabiting the small island of Queimada Grande, on the southern coast of São Paulo State. The lizards were collected on November 1997 (spring) and on July 1998 (winter). Most lizards were perched above ground, mainly on herbaceous vegetation. Mean lizard body temperatures were significantly higher in spring (32.6 ± 1.9ºC) than in winter (28.5 ± 2.4ºC), as were air temperatures. Mean litter size of females was 2.7 (range 2-3). The diet was composed of a diverse array of arthropods and some small fruits. Of the 19 lizards examined, 16 (84.2%) harboured helminths. Three species of helminth (one acanthocephalan and two nematodes) were found infecting the lizards. Compared to other M. macrorhyncha populations previously studied in mainland areas, the Queimada Grande population appears to be less strongly associated to bromeliads, to consume plant matter (fruits) more frequently, and to have a poorer helminth fauna.

Patterns of infestation by chigger mites in four diurnal lizard species from a restinga habitat (Jurubatiba) of Southeastern Brazil

We studied the parasitism by larvae of the chigger mite Eutrombicula alfreddugesi on the lizard community of Restinga de Jurubatiba, Rio de Janeiro State, Southeastern Brazil. We investigated the patterns of infestation (prevalence and intensity) of chigger mites in four sympatric lizards: Tropidurus torquatus, Mabuya agilis, M. macrorhyncha and Cnemidophorus littoralis. All lizards collected were checked for the presence of mites, which were counted under stereomicroscope. We tested the relationship between intensity of infestation and lizard body size for each species using regression analysis. The prevalences and mean intensities (+ one standard deviation) of infestation on each host species were, respectively: 100%; 86.4 + 94.6 in T. torquatus (n = 62); 100%; 20.9 + 9.3 in M. agilis (n = 7); 100%; 11.1 + 13.1 in M. macrorhyncha (n = 12); and 95.2%; 19.1 + 16.8 in C. littoralis (n = 21). Only for C. littoralis did body size significantly affect the intensity of infestation (r = 0.27, p = 0.02). For all lizard species, the body parts where chiggers occurred with the highest intensity were those of skin folds and joint regions.

Relative feeding specialization may depress ontogenetic, seasonal, and sexual variations in diet: the endemic lizard Cnemidophorus littoralis (Teiidae)

We investigated the feeding habits of the teiid lizard Cnemidophorus littoralis in the markedly seasonal habitat of Restinga da Barra de Maricá (22º57'S, 43º50'W), Rio de Janeiro State, Brazil, to evaluate to what extent its diet is ontogenetically, sexually, and/or seasonally conservative. Lizard stomach contents were analyzed, identified, counted, estimated for volume (in mm³), and grouped in four classes (active, sedentary, and clumped preys, and plant material). The relative contribution of each food class to the total prey volume consumed by adult males and females and juveniles was compared in three ways: between juveniles and adults, sexes, and seasons (wet and dry). Sexual dimorphism in head size was tested by comparing head width and jaw length using analysis of covariance (ANCOVA). Isopterans were the most important prey item, occurring in 93% of the lizard stomachs examined and corresponding to 96.4% of total prey content and 69.7% of total prey volume. They occurred in high frequencies in the stomachs of C. littoralis throughout all study months. We found no sexual, ontogenetic, or seasonal differences in C. littoralis diet although the sexes differed significantly in head width. We concluded that isopterans are the main item in the diet of C. littoralis in Restinga da Barra de Maricá, both for juveniles and adults. The lack of seasonal, sexual, or ontogenetic variation in its diet results from the massive consumption of these insects. Isopterans are small, occur in clumps, and are available year-round, and thus are an advantageous food item for the active forager C. littoralis. We also found sexual dimorphism in the head size of C. littoralis: males have wider heads than females. This dimorphism, however, does not seem to be related with the diet of the species, and is probably a result of sexual selection.