I've seen several down jackets stating what species of down the jacket is filled with, i.e. Duck, Goose, etc.
What are the differences between the various species' down and which is best?
From The Feather Company, London
Duck down is the most common type of filling. Down from geese is usually larger than down from ducks. Muscovy down has features very similar to eider down i.e. they are more crooked and intertwined. Eider down is the world's lightest and best insulating material. It is a very exclusive and collected manually when the eider bird has left the nest.
Down is the best insulating material in the world and is also very good at regulating heat and moisture in duvets. Generally speaking, down quality is dependent on the raw material: healthy adult birds produce better quality down, which has a better insulating capacity and lasts longer
In decreasing order of quality:
Eider Duck Down
Siberian Goose Down
Moskus Down
Goose Down
Duck Down