No abstract

EcologíaVariación espacial y temporal de la herpetofauna en ecosistemas de sabanas inundables de la Orinoquía-Colombia RESUMENSe comparó la diversidad de anfibios y reptiles en bosques de vega, de galería y sabanas y entre las épocas seca y de lluvias en ecosistemas de sabanas inundables. Se realizó un muestreo en tres sitios en cada época climática, mediante los métodos de encuentro visual y trampas de caída con barreras de interceptación. El esfuerzo de muestreo para cada cobertura fue de 252 horas de recorridos y 504 horas de trampas de caída. Se registraron 23 especies de anuros y 37 especies de reptiles: 10 serpientes, 13 lagartos, un anfisbénido, cuatro tortugas, y un cocodrilo. La mayoría son nuevos registros para la zona nororiental del departamento de Casanare. La mayor riqueza y abundancia se reportó en las sabanas. El clima no es una variable determinante en la riqueza, pero si en la abundancia de la herpetofauna. Las sabanas son de gran importancia para el mantenimiento de la estructura de los ensamblajes de herpetofauna a lo largo del ciclo anual, los bosques son zonas de refugios de diversidad durante el periodo de inundación.Palabras clave. Anfibios, bosques de ribera, diversidad, reptiles, sabanas neotropicales. ABSTRACTWe compared the diversity of amphibians and reptiles in forest of vega, gallery forest and savannas in flooded savannas ecosystems. One sampling was conducted at three sites in each climatic season, using visual methods and encounter barriers of interception with pitfall traps. Sampling effort for each type of vegetation was 252 hours, and 504 hours of pitfall traps. A total of 23 species of anurans and 37 species of reptiles (ten snakes, thirteen lizards, one worm lizard, four turtles and one crocodilian) were recorded. Most are new records for the northeastern region of Casanare department. The greatest richness and abundance of herpetofauna were found in savannas. The weather is not a determining variable in the richness but in the abundance of the herpetofauna. Savannas are very important for maintaining the structure of herpetofauna assemblages throughout the annual cycle, forests are areas of maintenance of diversity during the flood period.

We characterize the diet of Craugastor raniformis, a terrestrial frog that inhabits the tropical dry forest in Colombia. The diet is constituted mostly of orthopterans, millipedes, arachnids and ants. Considering the morphological characteristics of this species, diet composition, gut vacuity index, trophic niche breadth and diversity, we consider this species would behave like a sit and wait predator.

Species of Bufonidae and Leptodactylidae are common in the Colombian tropical dry forest. Although some of them are associated with active foraging and consumption of termites and ants, their trophic ecology is mostly unknown. The diet of five anuran species of Bufonidae (Rhinella horribilis, R. humboldti) and the leptodactylid subfamily Leiuperinae (Engystomops pustulosus, Pleurodema brachyops, and Pseudopaludicola pusilla) was examined at six sites of the Colombian Caribbean in fragments of dry forest and different land uses. A total of 310 food items were identified. The greatest contribution was represented by Coleoptera, Hymenoptera (Formicidae), Isoptera, and Diptera. The species differed in number and volume of prey. Except for Pseudopaludicola pusilla, which behaves as a generalist predator, species had high intake of termites and ants. Engystomops pustulosus preferred termites, Pleurodema brachyops had high consumption of ants and termites, and the two bufonid species were myrmecophagous. Except for Pseudopaludicola pusilla, predator and prey size was related. Most species have overlapping diets (spatially and temporally) when analyzing food items identified at the order level. However, the richness of different prey within these orders allows the coexistence of species. The diet of these species presents similar trends in different habitats throughout their distribution area.

Anuran–prey selection might be mediated by traits, either by mismatches in predator and prey traits (preventing interactions) or by predator selection of prey traits (encouraging interactions). These effect traits could be summarized in two contrasting foraging strategies: “active” and “sit‐and‐wait” foragers. We evaluated whether anurans could be classified into groups of species sharing traits associated with their diet, and what is the relation between particular effect traits of anurans and their prey. We collected anurans and identified their stomach contents once during dry, minor, and major rain seasons in six dry forest sites in the Colombian Caribbean. For each of the 19 anuran species and 436 prey items, we registered six effect traits. We applied RLQ and fourth‐corner methodologies to relate predator and prey traits through their interaction matrix. Predators were assigned to five groups according to their differences in locomotion, body shape, proportion of the jaw width, mode of tongue protrusion, and strata preferred. Regarding preys, species were assigned to four groups according to their gregariousness, body shape and hardness, defensive traits, and mobility. Body size of both, predators and prey, had a minor contribution in the group assignment. We found that predators using active search target low‐mobility preys, whereas species using sit‐and‐wait strategy target highly nutritive prey that are difficult to manipulate. By linking amphibian diet with foraging strategies, we hope to contribute to the understanding of mechanisms behind anuran–prey food web patterns and to build more realistic models of functional response to changing environments.Abstract in Spanish is available with online material.