little egret

The white feathers of the little egret make it an eye-catcher on the riverside. Part of a group commonly known as the white egrets, it is an extremely well-known bird that lives in close proximity to residential areas. All white egrets, such as the Chinese egret and the Great egret, are pure white and have impressively long necks and beaks reminiscent of a crane. Originally migratory birds, white egrets can be seen throughout the year in Japan as many of them have become resident birds. White egrets are carnivores that mainly feed on aquatic animals like fish and frogs. Wading through the shallows, they thrust their beak into the water to catch prey. In particular, the little egret displays fascinating hunting behavior. Upon close inspection, the little egret can be seen shaking its legs at high speed. Fish under the rocks are frightened out of hiding, only to be swiftly snapped up. On occasion, the little egret takes flight in pursuit of fish, and is even known to drop garbage into the water to attract its prey, indicating a high level of intelligence. But, why is it that the little egret is capable of hunting in this way? The little egret has one eye on each side of its head, just like your average bird. However, it has no hair at the base of its beak, facilitating full frontal vision with both eyes. In other words, the little egret is capable of binocular vision. But that’s not all. Birds have a translucent third eyelid called a nictitating membrane that reduces diffused reflected light. Working in the same way as the polarizing filter on a camera, this membrane allows birds to obtain a high-level of contrast. The cloudy appearance of the little egret’s nictitating membrane has been experimentally proven to emphasize colors close to yellow, a mechanism that is still somewhat of a mystery. A combination of binocular vision and this cloudy membrane may help the little egret spot fish against the yellowish rocks and riverbed. Ostriches, crows, some pheasants, and the little egret are the only known birds with a cloudy nictitating membrane. While it is thought that this cloudy nictitating membrane also facilitates infrared vision, there is still no data confirming what wavelengths it can detect, or to what degree yellowish colors are emphasized. Whatever the case, the little egret’s excellent ability to find prey is certainly the key to its diverse repertoire of hunting techniques. Humans do not have such refined sensors with which to measure the natural world. However, humankind posses the power of analysis, one that goes beyond our natural limitations. The protection of this diverse and beautiful earth through the analysis of nature is a mission that has been entrusted to humankind.

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