Trophic ecology and foraging behavior of Tropidurus hispidus and Tropidurus semitaeniatus (Squamata, Tropiduridae) in a caatinga area of northeastern Brazil

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.

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.

Trophic ecology and foraging behavior of Tropidurus hispidus and Tropidurus semitaeniatus (Squamata, Tropiduridae) in a caatinga area of northeastern Brazil

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.

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.

The effects of seasonality on the foraging behavior of Tropidurus hispidus and Tropidurus semitaeniatus (Squamata: Tropiduridae) living in sympatry in the Caatinga of northeastern Brazil

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.

The effects of seasonality on the foraging behavior of Tropidurus hispidus and Tropidurus semitaeniatus (Squamata: Tropiduridae) living in sympatry in the Caatinga of northeastern Brazil

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.

The effects of seasonality on the foraging behavior of Tropidurus hispidus and Tropidurus semitaeniatus (Squamata: Tropiduridae) living in sympatry in the Caatinga of northeastern Brazil

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.