This study assessed the reproductive and fat body cycles of Tropidurus hispidus (Spix, 1825) and T. semitaeniatus (Spix, 1825) in an area of caatinga in the Serido of Rio Grande do Norte, Brazil, from October 2006 to May 2008. In both species, the females were reproductively active from the middle of the dry season to the beginning of the rainy season. Female reproductive activity was influenced by precipitation, whereas males exhibited spermatozoa in their testes throughout the year, and their reproductive activity was not related to any of the climatic variables analyzed. Mean clutch size (± SD) was 8.1 ± 2.0 and 2.1 ± 0.6 eggs in T. hispidus and T. semitaeniatus, respectively, and was significantly related to female body size only in T. hispidus. The fat stock varied inversely with reproductive activity in the two species, and there was no difference in fat body mass between females and males. The effects of precipitation on the length of the breeding season of these two Tropidurus species suggest that their reproductive cycles are related to the microclimatic conditions suitable for embryo development, as well as for the neonates' emergence and survival especially during the rainy season, which may offer greater food availability to the hatchlings.

Este estudio evaluó los ciclos reproductivos y de grasa corporal de Tropidurus hispidus (Spix, 1825) y T. semitaeniatus (Spix, 1825) en una área de caatinga en el Seridó de Rio Grande do Norte, Brasil, de octubre de 2006 a mayo de 2008. En ambas especies, las hembras se encontraron reproductivamente activas a partir de mediados de la estación seca para el inicio de la temporada de lluvias. La actividad reproductiva de las hembras fue influenciada por las precipitaciones, mientras que los machos presentaron espermatozoides en los testículos durante todo el año, y su actividad reproductiva no fue relacionada con ninguna de las variables climáticas analizadas. El tamaño medio (± DE) de la nidada fue de 8.1 ± 2.0 y 2.1 ± 0.6 huevos en T. hispidus y T. semitaeniatus, respectivamente, y se relacionó significativamente con el tamaño corporal de la hembra solo en T. hispidus. La reserva de grasa varió inversamente con la actividad reproductiva en las dos especies, y no hubo diferencia en la cantidad de grasa corporal entre hembras y machos. Los efectos de la precipitación sobre la duración de la temporada reproductiva de estas dos especies de Tropidurus sugieren que sus ciclos reproductivos están relacionados con las condiciones microclimáticas adecuadas para el desarrollo del embrión, así como para la emergencia de los recién nacidos y su supervivencia, especialmente durante la temporada de lluvias, que es la que puede ofrecer una mayor disponibilidad de alimentos para las crías.

We studied the feeding ecology of a population of Coleodactylus natalensis Freire, 1999, an endemic gecko of Atlantic Forest fragments in the state of Rio Grande do Norte, northeastern Brazil. Lizards (N = 49) were collected manually through active search in the four habitats of Parque Estadual Dunas de Natal, type locality of the species. In the laboratory, we measured the lizards and registered the number of consumed prey items identified to Order, its dimensions and frequencies. We also collected samples of leaf litter in each habitat to determine prey availability. Females were significantly larger than males, but head size did not differ between the sexes. The most important prey categories in the diet of C. natalensis based on number, volume and frequency were Isopoda and Araneae. Prey categories with highest importance indices in the diet were Isopoda, Araneae, Homoptera and Gryllidae. The diets of adult males and females were similar with respect to prey size, but differed qualitatively, mainly due to the larger trophic spectrum of females. We found some variations on trophic niche breadths and food preferences of lizards between habitats, but in general niche breadths were intermediate, and the most elected prey categories were Isopoda, Araneae, Homoptera and Thysanoptera. High electivities for Isoptera and Gryllidae occurred only in the open habitats (restinga and dunes), and for Mantodea in the forested habitats (high and low forest). Collembola was consumed in the same proportion of the environment, and Acarina and Formicidae had negative values of electivity, indicating rejection. We conclude that the population studied seems to have a selective diet, preferring relatively large prey items that are less abundant in the leaf litter, and possibly avoiding potentially toxic prey.

We studied the thermal ecology and thermoregulatory behavior of Coleodactylus natalensis Freire, 1999 in a remnant of a northern coastal patch of the Brazilian Atlantic Forest. Data were collected during four 20-day field excursions over the course of one year. We assessed the importance of substrate and air temperatures, in addition to time of exposure to sunlight, as relevant factors for the regulation of body temperature in this species. After each specimen was captured, body (Tb), substrate (Ts) and air (Ta) temperature were measured 10 cm above the ground, using a temperature sensor coupled to a fast response thermo-hygrometer. Ad libitum and focal animal methods were used to describe thermoregulatory behavior. The mean body temperature of C. natalensis was 31.3 ± 3°C (amplitude of 26.9 and 38.4°C, n = 20). A positive relationship was found between Tb and environmental temperatures; further, substrate temperature explained the additional variability of temperature variations in this species. With respect to environmental observations, individuals of C. natalensis did not expose themselves directly to the sun, moving equally between full and filtered sun. Our results indicate that C. natalensis is umbrophylic and a passive thermoregulator.

Este estudo objetivou analisar a variação sazonal na composição da dieta e no comportamento de forrageamento de Tropidurus hispidus (Spix, 1825) e T. semitaeniatus (Spix, 1825) e medir a intensidade de forrageamento (número de movimentos, tempo gasto parado, distância percorrida e número de ataques sobre itens-presa) destas espécies em uma área do bioma caatinga no estado do Rio Grande do Norte, Brasil. Hymenoptera/Formicidae e Isoptera predominaram na dieta de ambas as espécies durante a estação seca. A predação oportunística de larvas de Lepidoptera, larvas/adultos de Coleoptera e ninfas/adultos de Orthoptera ocorreu na estação chuvosa, contudo as formigas foram os itens-presa mais importantes. O número de itens alimentares foi similar entre as espécies de lagartos em ambas as estações; no entanto a sobreposição para o número de presas foi menor na estação chuvosa. As presas ingeridas durante a estação chuvosa por T. hispidus foram maiores do que aquelas de T. semitaeniatus. As comparações sazonais da intensidade de forrageamento entre as duas espécies mostraram diferenças, principalmente na estação chuvosa, quando T. hispidus apresentou menos movimentos e ataques sobre presas, e mais tempo gasto parado comparado a T. semitaeniatus. Embora ambos os lagartos sejam forrageadores senta-e-espera, T. semitaeniatus é mais ativo do que T. hispidus. A dieta e o comportamento de forrageamento de T. hispidus e T. semitaeniatus mostram sobreposição sob condições limitantes durante a estação seca, e são fatores segregativos que podem contribuir para a coexistência dessas espécies na estação chuvosa.

This study aimed to analyze the seasonal variation in diet composition and foraging behavior of Tropidurus hispidus (Spix, 1825) and T. semitaeniatus (Spix, 1825), as well as measurement of the foraging intensity (number of moves, time spent stationary, distance traveled and number of attacks on prey items) in a caatinga patch on the state of Rio Grande do Norte, Brazil. Hymenoptera/Formicidae and Isoptera predominated in the diet of both species during the dry season. Opportunistic predation on lepidopteran larvae, coleopteran larvae and adults, and orthopteran nymphs and adults occurred in the wet season; however, hymenopterans/Formicidae were the most important prey items. The number of food items was similar between lizard species in both seasons; however the overlap for number of prey was smaller in the wet season. Preys ingested by T. hispidus during the wet season were also larger than those consumed by T. semitaeniatus. Seasonal comparisons of foraging intensity between the two species differed, mainly in the wet season, when T. hispidus exhibited less movement and fewer attacks on prey, and more time spent stationary if compared to T. semitaeniatus. Although both lizards are sit-and-wait foragers, T. semitaeniatus is more active than T. hispidus. The diet and foraging behavior of T. hispidus and T. semitaeniatus overlap under limiting conditions during the dry season, and are segregative factors that may contribute to the coexistence of these species in the wet season.

In this study, we performed field observations of 38 and 84 specimens of the lizards Tropidurus hispidus (Spix, 1825) and Tropidurus semitaeniatus (Spix, 1825), respectively, inhabiting a Caatinga in the state of Rio Grande do Norte, northeastern Brazil, in order to describe the foraging behavior, measure the foraging intensity (number of movements, time spent stationary, distance traveled and number of attacks on preys) and investigate the effects of seasonality on the foraging strategies of these two species of lizards. During the dry season, both species showed no significant differences in foraging intensity. In the wet season, on the other hand, only the distance traveled was similar for both species. Tropidurus semitaeniatus displayed a larger mean number of movements (9.8 ± 1.2) and attacks on preys (1.7 ± 0.3) when compared to T. hispidus (3.0 ± 0.8 moves; 0.3 ± 0.1 attacks). Additionally, mean time spent stationary was significantly longer for T. hispidus (596.6 ± 1.0 seconds) than for T. semitaeniatus (587 ± 2.1 seconds). Results suggest that the low number of movements and short distance traveled (maximum of 1000 cm during 10-minute intervals) are consistent with the categorization of T. hispidus and T. semitaeniatus as sit-and-wait foragers. Given our results, we conclude that both species co-exist under limiting conditions during the dry season, with similar foraging behavior and similar rates of foraging intensity, segregating with respect to these variables in the wet season.