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Species of the Week
Dendrobates tinctorius | Dyeing Poison Frog

Amphibian News Archive
The startlingly bright colors and intricate patterns of Neotropical poison frogs are icons of warning coloration. Barnet et al. (2018) show in a recent paper that at least in Dendrobates tinctorius, the bright color patterns may simultaneously scream "Here I am!" to nearby would-be predators, yet be relatively undetectable to predators farther away. They measured the frog’s complex patterns of yellow and blue on a black background as perceived by different types of potential predators (reptiles, birds, mammals). Using a machine learning algorithm, they assessed the ability of different visual systems to discriminate D. tinctorius from a leaf litter background at different distances. Close up, discrimination by each visual system was highly accurate, but far away, discrimination declined dramatically. In the field, they used model frogs with different color patterns to show that cryptic (brown and black) models had fewer predation attempts against a natural leaf-litter background, whereas background did not affect the attack rates on purely aposematic (bright yellow) models. The tinctorius color pattern also had lower attack rates against the natural background, indicating an element of protective camouflage. Experiments with human "predators" trying to find frogs on a computer screen showed the tinctorius color pattern was just as aposematic as the bright yellow morph close-up, but from a distance was just as hard to see as cryptic coloration. They conclude a kind of perceptual averaging occurs, in which the different colors of the intricate pattern blend together at a distance, making the frogs virtually invisible in their natural background.

Current number of amphibian species: 7,901 (Jul 18, 2018) Newly added species