Identification of hen mallard next to a gadwall in the sky.

[jjawz]

I'm having a hard time distinguising between hen gadwalls and hen mallards in the sky, they pretty much look the same to me except for the blue on the wing. Can anyone give me a suggestion on what will help me identify the two. By the way I can't even begin to tell you guys how many hen mallards I saw this morning, no drakes though. I didn't end up shooting any though. Thanks guys

[Grute Man]

Try this one.  I saw it in an old post.  Im not a waterfowler per say so this is the best help I can offer.  Good Luck.

http://www.npwrc.usgs.gov/resource/birds/duckdist/index.htm