Hainan migratory bird elderly refers to the elderly who come to Hainan for the winter from the north every winter. Like birds, they choose different regional environments to provide for the elderly with the change of climate. Winter in the north is particularly cold, and elderly migratory birds will choose to come to the south for the winter and return to the north in summer.
In fact, not only those who go to Hainan for the winter are called migratory birds, but all those who choose different regional environments to support the elderly with the change of climate, whether they go to warm places in winter or cool places in summer, are called migratory birds.