Abstract Understanding how different environmental factors influence species occurrence is a key issue to address the study of natural populations. However, there is a lack of knowledge on how local traits influence the microhabitat use of tropical arboreal lizards. Here, we investigated the microhabitat selection of the poorly known lizard Tropidurus lagunablanca (Squamata: Tropiduridae) and evaluated how environmental microhabitat features influence animal’s presence. We used a Resource Selection Function approach, in a case/control design where we analyzed the effect of substrate temperature and tree’s diameter at breast height (DBH) in the probability of presence of lizards using mixed Conditional Logistic Regression. We found that T. lagunablanca uses trees with DBH from 0.40 m to 4 m and substrate temperatures ranging from 25.9°C to 42°C. Moreover, we showed that thickness of the trees and substrate temperatures significantly increased the probability of presence of T. lagunablanca individuals, being the probability of presence higher than 50% for trees up to 1.5 m DBH and temperature of substrate up to 37.5°C. Our study probed that T. lagunablanca individuals choose trees non-randomly, selecting thicker and warmer tree trunks. This information advances the knowledge of the spatial ecology of Neotropical arboreal lizards and is relevant for conservation, putting an emphasis on preserving native vegetation in the Pantanal.

Resumen Los caimanes de la especie Caiman latirostris, distribuidos ampliamente por América del Sur, son depredadores oportunistas. Estos animales presentan variación ontogenética en su dieta de forma que los individuos jóvenes, que se alimentan inicialmente de invertebrados, van incorporando vertebrados a la dieta de manera gradual, a medida que crecen. Sin embargo, la falta de experiencia lleva, en ocasiones, a los caimanes jóvenes a consumir presas peligrosas, como anfibios venenosos. La intoxicación causada por ingerir un individuo de Rhinella diptycha puede ocasionar irritaciones locales al caimán, e incluso llevarle a la muerte. Para evitar esta amenaza, algunos animales utilizan estrategias de alimentación especiales, como comenzar a ingerir la presa por la parte posterior o comer solamente las vísceras. En esta nota presentamos el primer registro de un evento de depredación de un individuo adulto del sapo venenoso R. diptycha por parte de un individuo joven de C. latirostris, que observamos en una charca del sudeste de Brasil. El caimán esperó a que el sapo estuviera muerto antes de comenzar a tragarlo, lentamente, comenzando por la parte anterior de su cuerpo. No observamos ninguna señal de que la ingestión de la presa afectara al caimán, incluso algunas horas después de haberla ingerido. Nuestro registro sugiere que el caimán podría ser tolerante o estar adaptado a comer este tipo de presas venenosas, por lo que recomendamos investigar las causas y mecanismos de este tipo de tolerancia.

Abstract Caimans of the species Caiman latirostris, which are widely distributed in South America, are opportunistic predators. They show ontogenetic variation in diet, with young individuals initially feeding on invertebrates and then gradually adding vertebrates in their diets as they grow up. However, due to inexperience, young individuals may end up eating dangerous prey, such as poisonous amphibians. The intoxication caused by eating an individual of Rhinella diptycha may produce local irritation to the caiman, and even lead it to death shortly after ingestion. To avoid this threat, some animals use particular feeding strategies, such as starting to eat the prey’s posterior part, or eating only its viscera. In this note, we report the first case of a predation event of an adult individual of the poisonous toad R. diptycha by a young individual of C. latirostris that we observed in a pond of the Southeast of Brazil. The caiman waited until the toad was dead before starting swallowing slowly, from the anterior part of the body. We did not observe any sign that the caiman was affected by the prey ingestion, even some hours later after ingestion. Our register suggests that the caiman may be tolerant or adapted to eat this poisonous prey and encourage research on the causes and mechanisms of this tolerance.