Perplexing Plumage – How to tell a female Mallard from a female Gadwall

How do you tell a female/eclipse Mallard from a female/eclipse Gadwall?

Head and bill shape

1. The mallard has a thick bill with orange blotches on the top.
2. If it has a streaked brown and tan overall body, what you are seeing is probably a Mallard.
3. Also, should it be a Mallard its head would be more rounded than a Gadwall’s.

Head colour

1. The mallard has a round head that is dark with black eye-line.
2. If your bird has white on the wingtips, then Mallard is the bird, as the Gadwall doesn’t have this.
3. For the last pointer, the mallard has a blue speculum patch.

Body

1. For one, the gadwall has a thinner bill and an orange line on its lower edge
2. Finely patterned silver-gray body? Gadwall is the probable bird,  although the Mallard can have a similar body.
3. The Gadwall has a two-toned head, which is dark above and light below.
4. Thinking of the Mallard’s blue speculum, I must say that the gadwall has a white patch on its wing.
5. If the head shape is puffy and slightly “blocky”, it indicates Gadwall though this distinction is hard to see.

So is it easy? Not necessarily!   But keep trying, looking out for these pointers, and it will get easier.