Diet of terrestrial anurans in an ephemeral and simplified habitat during the dry season in the Brazilian Cerrado

Amphibians often use ephemeral and simplified habitats during dry seasons in tropical biomes. These simplified habitats can have less prey available, but only a few studies focus on how their use affects frogs’ diet. Here we studied the diet of three terrestrial frogs (<i>Adenomera</i> sp., <i>Ameerega berohoka</i>, and <i>Rhinella ocellata</i>) at a riverbank exposed only during the dry season in the Brazilian Cerrado biome. Diets overlapped more than expected by chance and were composed mainly of social insects (ants and termites). Prey volumes were not related to the size of frogs or their head measurements. Frogs at the riverbank ingested less prey categories and fewer prey items in comparison to studies conducted in more stable and complex environments. We suggest that frogs were attracted to riverbanks by the humidity and availability of reproductive sites, opportunistically ingesting prey available in the habitat. The abundance of social insects allowed the presence of frogs specialized in ants, such as the bufonid <i>Rhinella ocellata</i> and the dendrobatid <i>Ameerega berohoka</i>.

在热带生物群系的旱季，两栖类常利用临时性且结构简化的生境。此类生境的可利用猎物资源相对匮乏，但目前仅有少数研究探讨此类生境的利用如何影响蛙类的食性。本研究针对巴西塞拉多（Cerrado）生物群系中一处仅在旱季出露的河岸生境，对3种陆栖蛙类开展食性分析，涉及物种包括 Adenomera sp.、Ameerega berohoka 与 Rhinella ocellata。三者的食性重叠度显著高于随机预期水平，且食谱主要由社会性昆虫（蚁类与白蚁）构成。猎物体积与蛙类的体型或头部量测指标无显著相关性。相较于在更稳定且复杂的生境中开展的同类研究，该河岸生境中的蛙类所摄入的猎物类别更少，猎物个体数也更少。本研究推测，蛙类因河岸生境的湿度条件与繁殖位点可获得性而聚集于此，并通过机会主义策略摄食生境中可获取的猎物。社会性昆虫的充足资源，支撑了以蚁类为特化食性的蛙类在此存续，例如蟾蜍科（Bufonidae）的 Rhinella ocellata 以及箭毒蛙科（Dendrobatidae）的 Ameerega berohoka。