Predator response to the coloured eyespots and defensive posture of Colombian four-eyed frogs

Deimatic displays, where sudden changes in prey appearance elicit aversive predator reactions, have been suggested to occur in many taxa. These (often only putative) displays frequently involve different components that may also serve antipredator functions via other mechanisms (e.g. mimicry, warning signalling, body inflation). The Colombian four-eyed frog, Pleurodema brachyops, has been suggested to gain protection against predation through putative deimatic displays where they inflate and elevate the posterior part of their body revealing eye-like colour markings. We exposed stationary artificial frogs to wild predators to test whether the two components (eyespot/colour markings, defensive posture) of their putative deimatic display, and their combination, provide protection from predation without the sudden change in appearance. We did not detect any obvious additive effect of defensive posture and eyespots/colour markings on predation risk but found a marginally-significant trend f..., We tested the effect of the defensive posture and eyespots/colour markings present in the putative deimatic display of P. brachyops by exposing 1000 frog models, divided equally in four treatments, to natural predators in four different study areas. Two treatments included the eyespot/colour markings in the posterior dorsal region. These characteristic markings in P. brachyops consist of two rounded lumbar glands in a black colour accompanied by a pair of orange spots. Four different types of models were thus used: defensive posture with visible eyespots/colour markings; defensive posture without eyespots/colour markings; resting posture with visible eyespots/colour markings; and resting posture without eyespots/colour markings. 250 models of each type were placed semi-randomly (no two models of the same type were placed consecutively), distributed in equal numbers in each of the four locations. The model sequence was determined using an Excel-based random numbers generator. 
In each st..., Excel and R.