Colour matching by arthropods in burned and unburned backgrounds in a Neotropical savanna

Abstract

Abstract The visual properties of the background occupied by organisms are a key aspect of visual camouflage. Changes in background coloration by fires may mediate the differential survival of prey against visually oriented predators and modify the prey camouflage strategy. This phenomenon may be common in environments where the fire is a continuous modulator of the community, such as Neotropical savannas. In this study, we investigated whether arthropods match burned and unburned trunks in coloration in order to camouflage relative to the visual system of potential bird predators. We also investigated in which type of the trunk the black and brown morphotypes of Ronderosia bergii (Orthoptera) preferentially occupy and whether the morphotypes present colour matching in the burned and unburned trunks. We recorded the arthropod community on backgrounds against which they had low contrast relative to other available backgrounds. We found that specimens of R. bergii preferentially occupy burned backgrounds. In addition, we also found that black morphotypes of R. bergii showed lower contrasts on burned trunks to the achromatic channel, while browner morphotypes showed lower contrasts on unburned backgrounds in the chromatic channel. We propose three explanations operating behind the observed pattern of the studied community: differential predation; background selection; and animal colour change.