Color may not serve as a deimatic mechanism in Red-eyed treefrogs (Agalychnis callidryas): evidence from an experimental study

Predator avoidance and antipredator mechanisms are ubiquitous in organisms affected by predation. One such mechanism, deimatic behavior, uses bright colors or contrasting patterns to intimidate a potential predator in such a way as to provide the prey with a slight escape advantage during the approach or subjugation phase of the predation sequence. The extravagant coloration of Red-eyed treefrogs (Agalychnis callydrias) is commonly explained as functioning in such a capacity, yet this hypothesis remains untested. We assessed the reaction of wild-caught Red-eyed treefrogs to simulated predation events from forceps and a model bird. Red-eyed treefrogs opened their eyes rapidly and early during the predation sequence. Yet the orange feet and blue/yellow flanks of Red-eyed treefrogs were flashed rarely and only in association with an escape jump. To determine how the red eye color influences the tendency for a predator to attack, domestic chickens (Gallus gallus) were exposed to colored prey in three experiments including colored mealworms, clay frogs with their eyes painted red or green, and clay frogs in which the eyes were replaced with red light emitting diodes (LED) that could be turned on, thus stimulating the “flash” of color that a potential predator would experience when disrupting a sleeping frog. Young naïve chicks did not show aversion to striking red-colored mealworms relative to green or unpainted mealworms. Older chickens with free-ranging foraging experience increased attack frequency and intensity on clay frogs with red eyes. Model frogs in which red LED eyes were turned on during the initial interaction with chickens failed to induce a delayed reaction in subsequent strikes. While evaluation of interactions involving wild avian predators are necessary, these results suggest that the bright coloration of Red-eyed treefrogs may not function as a deimatic mechanism to prevent predation. The hypothesis that the bright coloration of the Red-eyed treefrog (Agalychnis callidryas) is used to startle predators was investigated.Live Red-eyed treefrogs rapidly flashed their eyes during a simulated predation event, but flashing feet and flank coloration were rare and occurred upon flight.Domestic chickens attacked model frogs with red eye color with greater intensity relative to models with green eyes.Domestic chickens did not exhibit hesitancy to strike a model frog when the eyes were replaced with red light emitting diodes and “flashed” upon interaction.The bright coloration of red-eyed treefrogs may not function to startle avian predators. The hypothesis that the bright coloration of the Red-eyed treefrog (Agalychnis callidryas) is used to startle predators was investigated. Live Red-eyed treefrogs rapidly flashed their eyes during a simulated predation event, but flashing feet and flank coloration were rare and occurred upon flight. Domestic chickens attacked model frogs with red eye color with greater intensity relative to models with green eyes. Domestic chickens did not exhibit hesitancy to strike a model frog when the eyes were replaced with red light emitting diodes and “flashed” upon interaction. The bright coloration of red-eyed treefrogs may not function to startle avian predators.