We might be at the top of the food chain but sometimes we just have to accept that animals have us beaten. The sad (yet amazing) truth is that there are a whole host of animals with perplexing perception far better than our own, and no animal does it better than the bird of prey.
Hawks, eagles and buzzards have an eyesight which is around 3-4 times as powerful as ours and allows them to hunt for rodents from as high up as 15,000 feet (that’s like spotting a 2mm insect from the top of an 18m tree), and maintain that pin-sharp vision while they scoop their prey up at speeds of around 100mph!
Of course, the animal kingdom is home to a spectacular ensemble of adapted eyes, but why exactly is it that these birds are so astounding?
One important factor is that they have much more powerful ciliary muscles (used to control the viewing of objects at varying distances) which can change the shape of the lens very rapidly to accommodate for the heights at which they hunt, and they also have the largest eye size relative to body size in the animal kingdom – an explanation why birds such as owls always look so shocked when we see them in pictures!
Perhaps the most important explanation though is the fact that these birds have four types of colour receptor in their eye, allowing them to see beyond the visible range and into ultraviolet… in fact, the sex of many birds is distinguished primarily through the presence of ultraviolet patches on their feathers! As well as this, their unrivaled receptors allow for the detection of magnetic fields and polarised light used for navigational purposes (…so that’s why we don’t see birds lost up in the clouds when we’re going on holiday!)
Birds such as the Bald Eagle also have a much higher density of receptors in their eyes than we do, allowing them much more effective visual acuity.
The most amazing thing about eyes though is the outstandingly broad scope of variation they have, and that’s what makes them so interesting. Some birds such as the gull and albatross have red or yellow oil drops in their colour receptors to allow for vision in adverse conditions… maybe we’ll be seeing a new line of eye drops heading our way in the future!
Rob writes for DirectSight, a leader in online eyewear.