Indicate the external structures of waterfowl such as geese, ducks, swans.

1) the presence of a swimming membrane on the legs to increase the swimming surface;
2) well developed down and a layer of subcutaneous fat – protection against hypothermia;
3) the presence of a coccygeal gland, which produces fat; birds lubricate their plumage, which protects them from wetting the feather cover.

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