Ecologia de Tropidurus torquatus (Wied, 1820) (Squamata, Tropiduridae) no Costão de Itacoatiara, Parque Estadual da Serra da Tiririca, municípios de Niterói e Maricá, RJ

Abstract

The lizard Tropidurus torquatus (Wied, 1820) has a wide geographical distribution and is abundant within its area of occurrence, thus making it a suitable species for ecological studies. In the present study we analysed the activity period, microhabitat use, foraging intensity, diet and thermal ecology of a T. torquatus population in Costão de Itacoatiara, State Park of Serra da Tiririca, situated in the municipalities of Niterói and Maricá, RJ. Data were collected in two steps: between July 2004 and January 2008 for the activity period, microhabitat use and foraging intensity studies and between July and August 2010 for diet and thermal ecology studies. All specimens collected were adults, with snout-vent length = 66,2 ± 12,0mm for males (n = 11) and 64,1 ± 8,0mm for females (n = 3). The activity period of T. torquatus in Costão de Itacoatiara was between 12 and 14 hours. In the dry season it had a unimodal pattern, with a peak between 09:00 and 13:00h, during the hottest hours of the day. In the rainy season the pattern was bimodal, with a peak between 8:00 and 9:00h and another between 16:00 and 17:00h. Both periods were associated with lower temperatures. There was no significant difference in activity period between seasons, which can be explained by the intense lizard activity period in dry season. The most used microhabitats were rock and bromeliads, which reflects the wide availability of these microhabitats in the study area. Foraging intensity showed no seasonal differences and the mean time that lizards were stationary was higher than the mean time lizards were moving. Diet was omnivorous and composed of arthropods, mainly insects, and vegetable matter, mainly fruits. The most consumed insects were Formicidae, Coleoptera, and other Hymenoptera such as small wasps and bees. Fruits, seeds and flowers consumed belonged to the Cactaceae Rhipsalis cereoides and Coleocephalocereus fluminensis, for which T. torquatus seems to be a potential seed dispersor. Larger lizards consumed larger items, but in smaller numbers, indicating a positive energetic balance. The consumption of vegetable matter varied with lizard size, increasing its proportion in older individuals. The mean activity temperature was 34.3 ± 2.5ºC, which was inside the range of mean temperature registered for other populations and Tropidurus species. Substrate was the most important environmental heat source for lizard thermoregulation along the dry season, explaining about 48% of the variation in lizard body temperature. The T. torquatus population was predominantly thermoconformer, mainly in relation to the substrate temperature.