How hawks hunt so well

 Researchers find they have the best colour vision of any animal (even humans)

The secret of the Harris's hawk's incredible hunting capability may have been found.

Biologists at Lund University found that the Harris's hawk has the best colour vision of all animals investigated to date - and in certain situations, even better than humans, according to Daily Mail.

They now believe it is the colour of the prey that helps predatory birds to detect, pursue and capture them. 

'I did not think that colour vision would be of such significance, rather that birds of prey simply have better visual acuity than humans and that was the reason they detect objects so early and at a great distance,' said Almut Kelber, biologist at Lund University. 

  Normally, the size of the eyes determines optical resolution and thus what people or animals can see, researchers say. 

The bigger the eyes, the higher the resolution. 

The size of the eyes in turn is usually linked to body size. Large body, large eyes; small body, small eyes. 

Particular to birds is a poor ability in general to see contrasts between different objects. Their contrast vision is almost ten times lower than ours.

However, there are exceptions, and the Harris's hawk (Parabuteo unicinctus) is one of them. 

The study by the Lund biologists shows that if an object is not distinguishable from the background and the colour is approximately the same, it is more difficult for a bird of prey than a human to detect it. 

If, on the other hand, the object has a different colour than the background, the Harris's hawk can detect it at twice the distance compared to human vision.

'It's exciting! The hawk weighs less than one kilo and has small eyes. Nonetheless, it can see many times better than us, even though it is so small and light', says Simon Potier.

Up to now, research has not focused on the significance of colour for the hunting success of birds of prey.  

Good colour vision is also particularly important in environments such as forests, where shadows for example can confuse visual impressions.

The findings may have practical importance for conservation, that is protecting threatened birds of prey from disappearing completely. 

One reason for the decline in the number of birds of prey is that they collide with structures such as wind turbines and power lines.

'Once we understand how birds of prey perceive their world, we can help to improve efforts to conserve and protect them', he concludes.