Raptor hunting

Raptor Hunting
One of the most spectacular sights in the world of birds is a kill of another bird by a stooping Peregrine Falcon. The falcon plunges steeply downward, wings partially closed, at speeds that can exceed 150 miles an hour. It was long thought that falcons and other raptors struck with their feet clenched like a fist. High-speed cinematographic studies, however, have shown that they strike their prey from above with all four toes fully extended. The Peregrine's victim is often ripped by the falcon's talons, producing a shower of feathers. Usually the prey is picked up off the ground afterward, although occasionally the falcon will stoop again and gather the tumbling bird before it falls to the ground.

Peregrines use other modes of hunting as well, sometimes diving past their prey and then zooming up from beneath to snatch it from behind and below, or simply catching a small bird from above with their talons. Sometimes they will patrol low over the ground like a harrier, attempting to flush game birds. The hunting success of Peregrines can vary widely with location, season, and even sex, as Cornell ornithologist Tom Cade showed with an interesting comparison. One breeding male in the eastern United States, hunting Blue jays almost exclusively, caught 93 percent of his targets one season. A breeding female in Australia was successful only 31 percent of the time, but she captured mostly coots which were more than five times as heavy as the Blue jays. Considering that the female probably weighed half again as much as the male, and analyzing the energy costs and benefits of both hunting patterns, Cade concluded that it took the male 49 kilocalories (kcal, what dieters normally just call a "calorie") to deliver 1,000 kcal of prey to the eyrie, while the female expended just 43 kcal to get the same job done. The female is more efficient, but is limited in the amount of time she can hunt because of her nest guarding duties. The somewhat less-efficient male probably delivered more nourishment to the young because he could spend more time hunting.

As a group, raptors exhibit an extraordinary variety of hunting techniques. Aside from owls (which are sometimes considered raptors) almost all are diurnal hunters, but a few like the European Hobby (a smaller relative of the Peregrine) will pounce on mice in the moonlight. Some are like the Peregrine in that they hunt at high speed. The Sharp-shinned Hawk, for example, often flashes through relatively thick woodland, maneuvering skillfully and often snatching passerines right from their perches. Others, like American Kestrels, Black-shouldered Kites, and the young of the very successful Red-tailed Hawk, often hover when hunting, and then drop steeply down on their targets. And still others, including adult Red-tails, soar as they watch for prey on the ground. But most hunting by raptors probably is done from perches with a commanding view from which the bird can scan the surrounding terrain with its telescope-like vision, where it can glide rapidly to gather in its prey. Interestingly, whether an American Kestrel hovers or perch-hunts depends in large part on whether there is a good breeze to hover in. Whichever technique is used, most prey of raptors are killed by the talons of the contracting foot being driven into their bodies; if required, the hooked bill is used to give a coup-de-grace. The exceptions are falcons, which ordinarily kill by biting into the necks of victims not dispatched in mid-air. Of course, there are some birds of prey (in addition to falcons) that employ rather specialized hunting techniques. Perched or hovering Ospreys plunge into water to grab living fish; Snail and Hook-billed Kites course around like harriers in pursuit of their less-than-agile preferred food: snails.

Richmond

A whole lot of incubating going on here. It doesn't look exciting , but it sure is. Inside the eggs a miracle is happening. A whole new falcon is being built in only 33 days. With hundreds of featherbudds, 8 toes, 2 ears, and 2 magnificent eyes. The falcon has the very best eyesight from all animals. He sees amazingly sharp from a distance of a few kilometers.

Flight depends on vision. A blind-folded bird cannot take off or fly properly because it is unable to orient itself. As predator bird ancestors adopted flight, they needed ways to find generally small prey from the air; they needed abilities to see at close range; and they needed to maintain focus at high speeds when in pursuit. The most successful birds of prey in any population were those with eyes better adapted to these demands. Over thousands of generations, natural selection led to populations of predator birds with greater visual capabilities.
How do predatory birds see more sharply than us? First of all they have especially large eyes. Large eyes let in the maximum amount of light, and they also allow for a large image. If a retinal image is spread over a greater number of visual cells, there will be greater resolution to the detail in the image. A bird's eye is so huge it occupies a significant portion of the skull

A flying bird hunting small prey far below must not only be able to distinguish how far away the prey is but also its size, shape, position, and motion. In response to these challenges, raptorial birds evolved precise accommodation and binocularity.
To determine the size and distance of a prey, animals rely on memory as well as visual information. They have to know (remember) how large the prey animal is, and then judge its distance based on the size of the image they see. It's also important to be able to develop a clear image of the prey, no matter what its distance.

The eye automatically focuses at a variety of distances using a natural neuromuscular adjustment called accommodation. In this process, tiny ciliary muscles surrounding the eye alter the curve of the lens so that it will focus on objects that are far or near. Raptor eyes have exceptional capabilities for accommodation. Thus, as a potential prey moves closer or farther from the eagle or hawk, the predator's eyes remain focused by rapidly changing the lens curvature.Binocularity allows for stereoscopic vision, which in turn allows for determination of distance. When an organism compares the slightly different images from the right and left eye, its brain automatically determines the distance to the object. Raptors, with their greater amount of visual field overlap, have the greatest abilities to use binocularity to develop a sharp, three-dimensional image of a large portion of their view.
The Deep Fovea:In birds that need accurate distance vision the most, (i.e.: birds of prey and some other species of bird), a second fovea evolved in the lateral part of the retina. A fovea is a small region of the retina where the concentration of rods and cones is the highest and therefore vision is the sharpest. Raptors, with their wide binocular field of view, have BOTH a central and lateral fovea. As a result, a substantial proportion of their visual field projects on the most visually receptive parts of the retina.
Pecten:Another unique structure in a bird's eye is the pecten. Pecten is a thin, greatly folded tissue extending from the retina to the lens. Predatory birds such as eagles and hawks have the largest and most elaborate pecten of all the birds. The pecten supplies nutrients and oxygen throughout the vitreous humour of the eye, thereby reducing the number of blood vessels in the retina. With fewer blood vessels to scatter light coming into the eye, raptor vision has evolved to be the sharpest vision known among all organisms.