What's wrong with my brother's feathers fluffy

Brother Ge's feathers are fluffy because of cold weather.This bird's cold resistance is not strong, so you must pay attention to keeping warm in winter. It is best to put it indoors. At the same time, you must pay attention to the wind from the wind. You can cover the cage with a cage, which can also keep warm.It should be noted that feeding must use some more nutritious foods, which will also help it to spend winter.Usually need to clean the bird cage to maintain the environmental hygiene to prevent birds from getting sick.