That way, they can keep one eye fixed on their prey. And while a spiral path is longer, the speed advantage more than compensates. Other birds, like owls, have their eyes located to the front giving them a much wider field of binocular vision. These birds may have a 180 degree field of overall vision with most of that binocular. This 'improvement' is possible because of a uniquely avian structure - the pecten .
Light passes through the droplet before entering the photosensitive outer segment.
Short-wavelength gradients would vary depending on the sun's angle in the sky. These gradients would increase in saturation as the sun moves from directly overhead to an angle of 90 degrees. Bennett et al. For each test the researchers let a female check out 4 different males, lined up behind transparent filters that blocked UV light. Then they let another female size up the same four males.