Cape Town – Researchers from UCT and WITS published the first scientific study proving the long-time hypothesis that dark ‘eyeliner’ feathers (known as the malar stripe) in Peregrine Falcons, reduce the amount of solar glare reflected into the falcon’s eyes, improving their ability to pinpoint and target agile prey in bright conditions.
The dark war-like make-up stripe smeared below athletes’ eyes when playing competitive sports is mimicked after the Peregrine Falcons’ dark ‘eyeliner’ feathers below their eyes.
Although not often spoken about, these black stripes worn by athletes help them spot fast-moving balls in competitive sports due to the reduced sunlight glare, giving a competitive advantage during high-speed chases just as with the malar stripe in the Peregrine Falcon.
The study was titled, Malar stripe size and prominence in peregrine falcons vary positively with solar radiation: support for the solar glare hypothesis, published in Biology Letters Journal by Michelle Vrettos, Chevonne Reynolds (from Wits) and Arjun Amar.
The study linked solar radiation levels to dark ‘eyeliner’ feathers in peregrine falcons; it suggested the dark ‘eyeliner’ feathers evolved according to the climate to act as sun shields to improve the birds’ hunting ability.
“The brighter the climate, the bigger the plumage on the Peregrine Falcon. The darker the climate, the smaller the plumage of the Peregrine Falcon,” said Amar.
UCT Master of Science student Vrettos, who carried out the research, said the solar glare hypothesis had become ingrained in popular literature but was never tested empirically before.
“Our results suggest that the function of the malar stripe in peregrines is best explained by this solar glare hypothesis.”
UCT Fitzpatrick Institute of ornithology professor Amar, who supervised the research, said they faced challenges as the researchers used pictures of Peregrine Falcons from around the world to carry out the study so they struggled initially to come with a measuring system for the plumage as the pictures illustrated the falcons at different scales and from different angles.