The swiftlet belongs to the bird family, Apodidae. It is a migratory bird that flies from Siberia and other places to the natural caves along the tropical coasts from December to March every year to breed its offspring. The swiftlet is smaller than the swallows we usually see, with grayish-brown back feathers with a golden sheen, long pointed wings, and all four toes growing forward.
The swiftlet has a well-developed mucus gland in its throat, and the saliva it secretes can be condensed into a solid in the air, which is the main material they use to build their nests. The swiftlet lays eggs in March and April every year. Before laying eggs, they fly in the sea and high altitude every day, sometimes up to thousands of meters, through the clouds and fog, sucking rain and dew, feeding on insects, seaweed, silverfish and other things.
After digestion, they burrowed into the depths of steep, shady, high-altitude cliff fissures and caves, spitting and building nests. It takes about 20 days to build. The nests are half-moon shaped, shaped like human ears, 6-7 centimeters in diameter, with a thick base and thin walls, weighing about 10-15 grams.
The outer part of the nest is neat and tidy, while the inner part is rough, like a loofah network. The whole nest is white, crystalline and elastic, attached to the rocky cliffs.
1. The nests built by the older swiftlets are made entirely by the large amount of mucus secreted from their throats, which is gradually condensed and has a pure texture, and this kind of bird's nests are of good quality and are the finest among all bird's nests. In the feudal imperial era, it was often chosen as a tribute, hence the name "Official Swallow", also known as "White Swallow".
2. The nests made by young swiftlets, due to their lack of nesting experience, are rough and contain more impurities and feathers. The raw material of bird's nests harvested at this time is called "Hairy Bird's Nest".
3. There is another kind of bird's nest that is moisturized by the red liquid seeping out from the red rock wall, and the part of the bird's nest close to the rock wall gradually turns red, also known as the "Blood Swallow" or the "Red Swallow", which contains a number of minerals, has good nutrients, and has very little production, which is regarded as the most precious bird's nest among all the bird's nests. It contains a number of minerals, good nutrition and very little production, and is regarded as one of the treasures of bird's nests.