What's wrong with the fluffy feathers of blue songs

The blue song is fluffy because it is cold.This kind of bird must pay attention to thermal insulation in winter, otherwise it is easy to be frozen to death.Bird cages are usually placed indoors, and do not hang at the door, so as not to blow cold wind.In addition, the drinking water provided for it must also control the temperature and do not let it drink cold water.Feeding can be used with insects and other feeds. Eating a lot of birds can also help enhance the ability of cold resistance.