The peregrine falcon is the fastest member of the animal kingdom and is renowned for its speedy hunting swoop, which it uses to catch prey.
While the birds are much admired, exactly how they achieve speeds of 200mph and precision when diving has remained a mystery.
But now a team of German scientists have studied the falcons using a series of cameras to investigate the birds’ aerodynamics, and have discovered that their feathers ‘pop up’ to reduce drag.
The birds catch prey by diving from a height at blistering speeds of up to 200mph (322kph), making it hard for scientists to see exactly what is going on.
To solve this, researchers from the Freiberg University of Mining and Technology and the universities of Bonn and Giessen, trained a small number of falcons to dive from the top of a dam to the bottom to retrieve a treat.
They did this so they could follow the birds’ flight over a predictable path, making it easy to map, according to the study published in the Plos One journal.
High speed cameras focused on different parts of the dam wall – which measured 200ft (60metres) tall – filmed the birds from different angles and the scientists used the footage to work out the bird’s diving trajectory.
This is almost impossible as there are no markers or reference points when filming the birds in the wild.
Armed with data, the researchers created a 3D plastic model of a peregrine falcon as if it was diving at full speed and analysed it in a wind tunnel.
They looked at the flow of air over the model’s surface by applying a thin layer of oil paint to the model and examining the streaking patterns left behind, which gave them an idea of wind flow lines.
They also tracked the movement of tiny particles illuminated with a laser in the wind tunnel, to see how they travelled over the surface of the bird, according to Plos Blogs.
By analysing the data and videos of the birds in flight, the scientists discovered that small feathers pop up between the birds’ wings on its back to boost its aerodynamics at its top speed during the dives and keep air flowing smoothly over its body.
The pop-up feathers reduce drag and can be likened to the flaps on an aeroplane’s wing, or even an aerofoil on a sports car.
They also found that the typical shape of the birds’ bodies and their wings at maximum diving speed in the experiment made a V-shape.
