Camouflage functions of juvenile giant panda colouration in forest environments

Abstract

The contrasting black-and-white coloration of the giant panda (Ailuropoda melanoleuca) has long attracted attention. Recent works suggest this contrasting pattern may generate camouflage-relevant visual effects. However, most previous studies have focused on adult pandas, whereas juveniles may face greater predation risk and may therefore represent a more ecologically relevant life stage for testing concealment hypotheses. We investigated whether juvenile panda coloration provides the potential for camouflage through background matching or disruptive coloration, and how this potential is shaped by vegetation cover, illumination and background position. We used life-sized juvenile panda models with natural and experimentally modified coloration by adjusting the relative proportions and spatial arrangement of white, black, and grey patches. Models were photographed in temperate woodland environments at ground level and against canopy backgrounds, under sunny and cloudy conditions, with and without vegetation occlusion. We quantified colour and luminance contrast, as well as edge-disruption metrics, using dichromatic canid and felid visual models. Natural juvenile panda coloration influences target-background contrast and edge-disruption, although these effects varies with vegetation, lighting, background height and visual model. Vegetation cover significantly reduced contrast and increased edge disruption metrics, while bright light condition only increased the metrics of edge disruption. Background position affected camouflage-relevant metrics in a context- and observer-dependent manner: under vegetation occlusion, canopy placement reduced chromatic contrast under felid-like vision, whereas ground-level placement reduced luminance contrast under both visual models. Alterations to patch extent and boundary arrangement modified camouflage-relevant metrics under specific environmental conditions, suggesting that the natural arrangement of pelage boundaries may enhance concealment under specific conditions. Overall, our findings support the hypothesis that juvenile giant panda coloration can produce visual effects consistent with potential camouflage, while highlighting the importance of habitat structure and viewing context in shaping camouflage.