South China Sea Myth

In late autumn, a large number of swallows from the north migrate south, and they will build nests on the island, and there are more and more nests in the cave, so it has become a scenery - swallow hole. But I didn't find any swallows and swallow's nests in this irregular black rock cave about 10 meters long, less than 5 meters wide, and no more than 4 meters at the highest point. The Swallow Cave and the surrounding coastal reefs are actually formed after the volcanic lava meets the rapid cooling of the seawater, and they are stacked on top of each other, like a book from the sky, with infinite charm and highlighting the infinite charm of nature. It's very easy to take pictures, and many visitors like to take great silhouettes in the cave, especially for wedding photos. But for photographers, the tripod has a low angle, supports the SLR camera to add an ultra-wide lens, and then adds a light absorber, and applies a small aperture for a long exposure. After the sun went down, we didn't wait for the long-awaited sunset, but the fog was misty, so we had to end up in Longluo Town for dinner first, and then go to the hotel to open a room and rest.

1 genus of passerine swallows. This genus of birds is small, with a body length of 130~180 mm. The body is long, with a small and pointed mouth, a large jaw, thin wings and a forked tail, and a long wing tip. Most of the back feathers are blue-black, so it was called Xuanniao in ancient times. The wingtips are long and good at flying, the beak is short and weak, and the beak is broad, which is the beak shape of a typical insectivorous bird. The feet are short and the claws are strong. There are 20 species in the world and 4 species in China, among which house swallow and golden-rumped swallow are more common. The house swallow has a chestnut red waist, an irregular horizontal band on the back chest, and a milky white abdomen. The golden-rumped swallow resembles a house swallow but is slightly larger. This kind of swallow waist chestnut yellow, very obvious and eye-catching, the lower body has fine black lines, easy to distinguish from the house swallow. Their habits are similar to those of house swallows, but most of them inhabit mountain villages. The upper body of the swallow is usually metallic blue-black, greenish-black, or brown; Some species have contrasting girdles, and the lower body is generally lighter (often white, light yellow, or fruity). There are usually subtle differences between the sexes, but males sometimes have more striking coloring and longer tails than females: young birds tend to have lighter feet and shorter tails than adults. Chirp: A chirp is a simple and fast chirp or buzz, while a normal chirp is longer lasting and the syllable sequence is varied.

Aircraft designers look for inspiration for the design of aircraft forms from birds such as swallows. The swallow's elongated body reduces drag during flight. The wings of the swallow have a high aspect ratio, which means that it can generate a lot of lifting force with little resistance. However, this aerodynamic efficiency comes at the cost of reduced maneuverability (e.g. compared to short, wide wings), but this disadvantage is partially compensated for by the forked tail, which improves the bird's maneuverability.

Some species have long tail feathers, which increase lift power, and function like the flaps of an airplane, ensuring that the air flow smoothly passes through the wings, and can delay the passage of air when the swallow is ready to land, so that the swallow can fly to a stop without increasing drag. Most species have short tarsal bones and small, weak legs, which are suitable for perching rather than walking, but those that burrow or nest on cliff faces have strong claws.

The above general description of the morphology of swift species is not applicable to the species of Swifts. They look more similar to other passerine birds, and may be somewhere between the swallow family and other passerine species. The legs and feet of river swifts are relatively large, and the related muscle tissues are less degraded in terms of size, number of muscles, and complexity. Their beaks appear thicker and thicker than those of other swallows, which are broad, flattened, and the bronchial rings in the vocal tubes are significantly less complete than those of other swallows. In addition, the hairy-winged swallows of the genus and the genus Sawwinged Swallow have a series of feathery branches on the margins of the outer primary flight feathers, forming a hook-like thickening layer, but their specific functions are not clear.

Yang Yang said: "I like swallows, in my eyes, swallows are auspicious birds. "Du Fu's "Double Swallows": The travel food is shocking and the two swallows are brought into this hall. It should be avoided from dryness and dampness, and it should be cool. The adopted son is in the dust, and the road is long when he comes. This autumn is here, and I am also far from the different places. "I still remember it vividly. There is also Du Mu's "Returning to Yan": "The painting hall sings and dances noisily, and people don't watch it. The long is the companion of the Jianglou envoy, and the dusk is still waiting to be leaned on. "It's something I'll never forget.

Li Ping said that swallows are most willing to get close to humans, and humans love this beneficial bird the most. Swallows generally return from the island in April ~ July to breed in farms close to farmland (insects). House swallows nest under the eaves of farmhouses. The nests are mostly made of mud and grass stems bonded with saliva, and are covered with fine weeds, feathers, rags, etc., and some Artemisia annua leaves. The nest is dish-shaped. 2 litters are bred each year, mostly from May to early June and mid-June to early July. Each clutch lays 4~6 eggs. The second litter is less, 2~5 pieces. Milky white eggs. Male and female co-incubate eggs. 14~15 days when the young birds emerge from the shell, and the parent birds are fed together. The chicks fly out for about 20 days, and then feed for another 5~6 days, and then they can eat by themselves. The food is all insects. The golden-rumped swallow resembles a house swallow but is slightly larger. This kind of swallow waist chestnut yellow, very obvious and eye-catching, the lower body has fine black lines, easy to distinguish from the house swallow. Their habits are similar to those of house swallows, but most of them inhabit mountain villages. Swallows are typical migratory birds. After breeding, the young birds follow the adults and gradually form into large flocks, migrating south for the winter before the first cold spell arrives.

Dr. Myth is a popular science writer and former popular science editor, he said that swallows are beneficial birds for human beings, mainly feeding on mosquitoes, flies and other insects, and can eat 250,000 pests in a few months, so we should protect them. Before winter comes, the swallows make their annual long journey—flying in flocks from the north to the far south, where they enjoy the warm sunshine and humid weather, leaving the frost and bitter winds of winter to the chickadees, grouses, and ptarmigans, which never fly south for the winter. On the surface, it is the cold of the winter in the north that makes the swallows leave their hometowns to spend the winter in the south, and then return to their hometowns from the south to have children and live and work in peace and contentment when the spring flowers bloom.