燕,俗称燕子,是一种候鸟,春分前后由南方来到长江、黄河流域,秋分过后又迁往南方。燕子不怕人,常在人前飞来飞去,还喜欢在人家的屋梁上筑巢孵育幼雏,因此又叫家燕。古代诗人对此多有描写:“燕子家家入,杨花处处飞”(孟浩然《赋得盈盈楼上女》);“故巢倘未毁,会傍主人飞”(杜甫 Yan, commonly known as the swallow, is a migratory bird. Before and after the vernal equinox, it came from the south to the Yangtze River and the Yellow River. After the autumnal autumn, it moved to the south. Swallows are not afraid of people. They often fly in front of people. They also like to build nests and incubate young chicks on people’s house beams. Ancient poets often described this: “Yan Zi’s family enters and Yang Hua flies everywhere” (Meng Haoran’s Fu Ying Ying Upstairs Girl); “If the nest is not destroyed, the owner will fly.”