6. WHICH BIRDS PROVIDE THE BEST DOWN?
Generally speaking, the best down comes from larger, more mature birds. When age and maturity are equal, goose down is better than duck down. However, down from an older duck is better than down from a younger goose. Larger Down has an extraordinarily high warmth-to-weight ratio. A duvet or sleeping bag filled with this down will be very light and incredibly warm. And it will last for decades.
On the other hand, poor quality White Goose Down will have smaller Down. It will not loft up, and has a rather low warmth-to-weight ratio. Even if there is more of this down by weight, it won't be as warm. Down from younger birds not only tends to have poor filling power, it will also tend to collapse in a relatively short time, because its fibers are too fragile. This is usually the difference between an inexpensive goose down product, and an expensive one
7. WHAT IS EIDERDOWN?
Eiderdown comes from the Eider Duck, and it is considered by some to be the finest quality of all down. It is also the most expensive. This down is unique in that it clings to itself, resulting in superior insulating power. The Eider Duck is a protected migratory species. Down is collected by hand from nests without disturbing the birds