Unsuccessful predation attempts by snakes on anuran amphibians: How successful are snakes?

• Autor(a) principal: Costa, William P. [UNESP]
• Data de Publicação: 2020
• Outros Autores: Trevelin, César C. [UNESP]
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/206725
• topic: Anurans; Ecology interaction; Predation attempts; Predator-prey; Snakes

Snakes and anurans are commonly involved in predator-prey interactions. The large number of records of predation events involving snakes and anurans suggests that snakes are frequently successful in their attempts to prey on these amphibians. However, two aspects of the data may lead to overestimates of the efficiency of the predator in these cases. One factor is that the principal source of the data on snake diets is the analysis of the stomach contents of snake specimens deposited in museums. The second is the paucity of data on the actual interaction between the predator and its prey, and the frequency with which the anurans are either able to escape the predator or are abandoned by snakes. Given this general lack of data on unsuccessful predator-prey interactions between snakes and anurans, the present study describes four unsuccessful predation attempts and discusses the potential consequences for both the predator and prey. These events involved three snakes of the family Dipsadidae and one of the family Viperidae, which are all venomous, and three anuran species of the family Leptadactylidae. The events were recorded at four localities in the Brazilian states of São Paulo, Minas Gerais, and Goiás between 2016 and 2018. In one of the four cases (Event 1), the anuran was able to escape, while in the other three events, the prey were abandoned by the snake. In one case (Event 3), the anuran was dead, while in the other two cases (Events 2 and 4), the animals were left with reduced mobility, and were thus more vulnerable to other predators. In two of these events (1 and 3), the predator attacked the anuran by grasping its posterior members, while in event 2, the strike was to the throat of the anuran, and in event 4, the anuran was grasped by its right flank. In the only case in which the prey was able to escape unharmed, the combination of the size of the animal and its resistance to the attack of the predator appear to have been decisive. In the three cases in which the anuran was abandoned by the predator, the initial point of contact may have determined the effectiveness of the attack, given the anatomical resistance exerted by the prey, even when it remains immobile. The fact that all the snakes included in the present study are venomous did not ensure the success of the predation attempts, which would have resulted in the waste of this resource (venom). Despite the difficulty of analysing unsuccessful predation attempts (and their consequences for both predator and prey) systematically, studies of this kind are necessary to advance the understanding of this type of interaction and, ultimately, to evaluate more conclusively the ecological dynamics of the relationship between snakes and anurans.