Have you ever seen a black water bird by a river or lake, suddenly diving into the water and disappearing without a trace? It is the protagonist of this issue - the common cormorant, a mysterious and efficient fisherman. What is so special about them? What are their lifestyles and habits? This issue will take you to find out. Common cormorants, which I have captured many times with my camera, are standing on rocks or branches, flapping their wings. It turns out that this is because the common cormorants' preen glands are not well developed and secrete less oil, so they cannot effectively apply oil to their feathers like other water birds, resulting in poor waterproofness of their feathers. Therefore, you can often see them drying their wings in the sun after diving. The common cormorant is a large water bird of the family Phalacrocorax, order Pelecaniformes. It is also known as "black fisherman", "water crow", "osprey", etc. Male and female are similar, with a body length of 72~87cm and a weight of 1300~2300g. The iris is emerald green, the beak is gray-black, and the tarsus is black. The cheeks, chin and upper throat are white, forming a half ring, with the rear edge stained brown. The exposed skin around the eyes and throat is yellow, and there is a sharp hook at the front of the mouth. The head, neck and crest of the adult bird in summer are black with a purple-green metallic luster, interspersed with white filamentous feathers, and white spots on the lower ribs. The shoulders are copper-brown with a metallic luster, and the tail is rounded in gray-black. The winter plumage of the adult bird is similar, but there are no white filamentous feathers on the head and neck, and no white spots on the flanks. Common cormorants have webbed feet between their toes, which help them swim more flexibly in the water. They like to move in small groups, are good at swimming and diving, and live in ponds, lakes, rivers, reservoirs, swamps and other waters. Common cormorants are also excellent diving predators, able to stay underwater for up to 40 seconds, using their strong legs and webbed toes to swim quickly in pursuit of fish. When the cormorant finds prey, it will quickly catch it with its beak and swallow it into its mouth. This efficient fishing method makes the common cormorant almost unrivaled in the water, so it has been domesticated and used for fishing since ancient times. The breeding season of common cormorants is from April to June. They build nests on trees, rocks or artificial structures. The nests are made of branches, grass leaves and feathers. The structure is simple but very sturdy. Each nest usually contains 3 to 5 eggs, and the male and female parents take turns incubating the eggs. After about 25 to 30 days of incubation, the baby cormorants will hatch. The chicks are fed by both parents, and the chicks will put their mouths into the throats of the parents to eat semi-digested food. After about 60 days of growth, they can fly and leave the nest. Common cormorants play an important role in the ecosystem. As top predators, they help control the number of fish and maintain ecological balance. In addition, they are very sensitive to environmental changes, so the number and distribution of common cormorants are often used as indicators to assess the ecological health of water bodies. Common cormorants are not only a part of nature, but also an indispensable part of the ecosystem. Next time you see common cormorants by a river or lake, stop and observe their behavior quietly to feel the wonder and harmony of nature. |
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