The ancient poems describing swallows include Xie Kejia's Remembering the King, Yan Shu's Broken Array, Du Fu's Shuang Yan, Xue Daoheng's Yesterday's Salt, Ouyang Xiu's Picking Mulberry Seeds, and Shuang Yan's description of swallows' traveling and eating surprised Shuang Yan and brought mud into this hall.
Swallow (scientific name: Hirundo rustica) is a passerine, which belongs to the family Yanidae. Its shape is small, its wing tip is narrow, its concave tail is short, its feet are weak, its feathers are not too many, its feathers are monochromatic, or it is blue or green with metallic luster. It is one of the most flexible finches. It mainly feeds on insects such as mosquitoes and flies, and nests in tree holes or cracks, or drills holes in sand banks, or sticks mud on walls or protruding parts of corridors, roofs and eaves in urban and rural areas, which are mainly distributed.
Swallows are beneficial birds for human beings. They mainly feed on mosquitoes, flies and other insects. They can eat 25, pests in a few months, so we should protect them. Swallows always travel long distances every year before winter comes-they fly from the north to the far south in droves, where they can enjoy warm sunshine and humid weather, and leave the frost and cold wind of winter to tits, grouse and Thunderbirds who never fly south for winter.
On the surface, it is the cold winter in the north that makes the swallows leave their hometown for the winter in the south, and then return to their hometown to have children and live and work in peace and contentment in the spring. Is this really the case? Actually, it is not. It turns out that swallows feed on insects, and they have always been used to preying on flying insects in the air, but they are not good at searching for insect food in tree cracks and ground gaps, nor can they omnivore berries and seeds and eat leaves in winter like rubber grouse and Thunderbird (some conifers do not shed their leaves even in winter).
however, there are no flying insects for swallows to prey on in winter in the north, and swallows can't be like woodpeckers and? Larvae, pupae and eggs of lurking insects are excavated by the woodfinch. The lack of food makes swallows have to make a great migration from north to south every year in order to get a broader living space. Swallows have become "nomads" in the bird family.