Staying alive during storms.
Contour feathers include the flight feathers and outer body feathers, which provide aerodynamic shape and wind and rain protection. Importantly, birds increase the water resistance of these feathers by preening and spreading oils on their feathers from a gland, called the uropigial gland, located at the base of the tail.
Downy feathers are the feathers underneath the contour feathers that are specifically adapted for providing insulation. Birds are capable of controlling each and every feather on their body. This allows them to 'puff up' during colder weather and increase amount of insulation around their body.
Along with this tremendous ability to self-insulate, birds can increase their metabolic rate and burn fat stores to generate heat. Due to this capability, it is generally considered that a lack of food, rather than extreme cold, is what poses the greatest problem for most birds. If a bird can keep eating then it has a continuous supply of energy to use for generating heat. In light of this, birds in good condition should be able to weather short periods of stormy weather by 'sitting tight'. Longer periods of bad weather can pose serious problems for finding food and maintaining energy requirements.
Enjoy the winter, and keep an eye on the eagles.