アメリカガモ Anas rubripes

A large duck, nearly identical to Mallard in size and shape but with a much darker chocolate-colored body. Bill is yellow with a slight greenish tinge on males, dull grayish-green on females. Note blue wing patch lacks any white borders. Fairly common in northeastern North America, especially along the coast. Large flocks can gather in the winter in saltmarshes and estuaries, but also occurs in smaller numbers on ponds and lakes, often mixed with other duck species. Frequently hybridizes with Mallard. Hybrids usually look darker than typical Mallards and may have an intermediate head pattern; also look for white in the tail or curled feathers above the tail to indicate Mallard genes.