They are birds of prey with surprising intelligence, fascinating predators with extremely elegant plumage. Among nocturnal birds, barn owls are unmistakable due to their appearance. Precisely the latter, however, makes them easily visible. But the barn owls they have learned to camouflage themselves in the darkness in a game of light and shadow in the moonlight.
This was revealed by a new scientific study published in the magazine PNAS and conducted by the Spanish center Estación Biológica de Doñana – CSIC. The researchers investigated the mimicry of the common barn owl, Tyto albawondering how this impacts night hunting.
The feathers of this iconic specimen are certainly different from those of other birds of prey and have a varied colour. No matter how silently the species may fly, the barn owl may alert prey with its livery.
However, the team found that the bird of prey, under certain conditions, it is almost “invisible” to its prey. But how? Camouflaging thanks to the Moon. In moonlit skies, the contrast of the barn owl’s plumage is indeed reduced. By doing so, the animals have no way to immediately detect danger and predation is successful.
The isotropy of the sky’s light is altered if the moon is present, allowing a compensation between the light coming from the celestial vault behind the owl and the light reflected from it towards the ground where the prey is located” explains the Estación Biológica de Doñana in a press note.
Starting from the paradox of plumage coloration and its implications, scholars therefore suggest another key to understanding the barn owl’s hunting abilities. Previously, it was believed that prey became paralyzed in fear at the sight of birds of prey.
But that’s not all because this new research would also explain why birds of prey with lighter feathers are more successful in predation than those with darker ones.
We examined the effectiveness of owls’ white plumage as a means of camouflage while hunting, taking into account the radiometric properties of the sky, the ground, and the owls themselves, as well as the mouse’s visual system, which is different from that of human owls. Our model indicates that it is sufficient for the Moon to be above the horizon at any phase for a flying owl to approach rodents from large regions of the night sky, always remaining below the detection threshold of the particular visual system of the moon” commented astrophysicist David Galadí, co-author of the study.
The phenomenon under study provides the basis for a better understanding of mimicry in other nocturnal species. Scholars, however, point out that this particular adaptation technique it may become less effective due to the ecological effects of light pollution.
