The peregrine falcon, one of the world's most common predatory birds, has the fastest vision in the animal kingdom, and can register nearly 130 frames per second, according to a recent study. In comparison, the researchers, including those from Lund University in Sweden, said humans see up to a maximum of 50 to 60 blinks per second.
They added that at a movie theatre, a speed of 25 images per second is sufficient for humans to perceive it as film, and not as a series of still images. According to the study, published in the Journal of Experimental Biology, the peregrine falcon has the fastest vision, registering 129 Hz (blinks per second) in a high light intensity environment.
Under the same conditions, the saker falcon can see 102 Hz and the Harris's hawk 77 Hz, the study noted. This is the first time scientists have studied the speed of vision among birds of prey, calculating how fast they sense visual impressions. "This is the first time. My colleague Simon Potier and I have examined the peregrine falcon, saker falcon and Harris' hawk and measured how fast light can blink for these species to still register the blinks," said study co-author Almut Kelber from Lund University.
The speed at which different birds of prey process visual impressions is related to their hunting needs, the researchers said. For the peregrine falcon which hunts fast-flying birds, the ability to spot ultraspeed movements helps them detect prey sufficiently early in order to have time to react. The Harris hawk is not as advantaged with very high vision speeds since it hunts small, slower mammals on the ground, the researchers explained.
Extremely acute vision, and the ability to rapidly process different visual impressions are crucial for a peregrine falcon as it dives down on its prey at the speed of a Formula One racing car -- over 350 kilometers per hour, according to the researchers. While studies have been done on the visual processing speeds of small insect-eating birds, this is the first study assessing the trait in birds of prey, the scientists added.
Commenting on the trait in such smaller birds, the researchers said they also have fast vision, indicating that bird species that hunt fast flying prey have the fastest vision. "It is something of a competition. A fly flies quite fast and has fast vision, therefore the flycatcher must see the fly quickly in order to catch it. The same applies to the falcon. To capture a flycatcher, the falcon must detect its prey sufficiently early in order to have time to react," explained study co-author Simon Potier from Lund University.
The scientists hope that the findings of the study will help in creating sufficiently well lit environments for falcons raised in captivity. The new knowledge can hopefully contribute to better conditions for birds held in captivity.
"Those who keep birds in cages must take care with the lighting and use cage lighting that does not shimmer, flicker or blink, because the birds will not feel well," Kelber said.