Why Down in a Comforter?
There are primarily two types of down: goose and duck. Down is the insulating material that clings to feathers of water fowl. Generally, birds that inhabit a colder climate, and those that spend more of their lives in icy water, grow a better quality down.
Down is the only insulation, both natural and synthetic, that will regulate its density according to temperature. Therefore, it will naturally keep you more comfortable in most climactic conditions.