Differences between a Mallard, Mottled, and American Black Duck? (1 Viewer)

[ShyGuyPal]

I'm very new to birding and am struggling with identifying some ducks I come across. I live in Texas and many times encounter flocks of Mallards.

Most of the time amidst these flocks are some members having different feather patterns across their face and/or body (ex. male with brown spots across the green, female with darker patterns and bill color). This could just be juveniles molting, but I can never fully tell if it really is a Mallard. It could also be cases of cross-breeding between American Blacks or Mottled, but once again they are so similar to each other I can't tell.

Is there a sure-fire way to distinguish between these three duck species and age gaps? I've used my bird books and online guides, but it is still difficult for me to tell. I'd really appreciate any tips or help on the issue!

 

[nartreb]

It's difficult. Making it worse, all three can interbreed.

It would take a rather long post to carefully describe these, as I'd have to cover females, breeding-plumage males, eclipse-plumage males, and transitional males for all three species. Then there are the weird domestic mallards and the uncommon hybrids and the rare intersex individuals.

Some areas to look for:
tail: breeding mallard males have curly upper tail coverts. (If you see these on an otherwise dull bird, it's either molting or it's a hybrid.) Female mallards have white tail feathers (not easy to judge as the other species are rather pale too, but it's a useful as one factor among others).
speculum: if you see strong white bars on both sides, it's a mallard. Strong black bars, it's probably an ABD (but both ABD and mottled can have thin white bars alongside black).
bill: orangeish (with a brown saddle) is typical for female mallard; olive is typical for female ABD. A strong black spot at the hinge of the jaw means Mottled.
Overall color pattern: male ABD *very dark* on body, with strongly contrasting pale head. Mottled duck like a less extreme ABD, with visible chevron patterns on body and a pale, unmarked underchin - very similar to female mallard.

Mottled vs female mallard: mottled has yellow bill with dark gape spot, brownish tail.

 

[ShyGuyPal]

It's difficult. Making it worse, all three can interbreed.

It would take a rather long post to carefully describe these, as I'd have to cover females, breeding-plumage males, eclipse-plumage males, and transitional males for all three species. Then there are the weird domestic mallards and the uncommon hybrids and the rare intersex individuals.

Some areas to look for:
tail: breeding mallard males have curly upper tail coverts. (If you see these on an otherwise dull bird, it's either molting or it's a hybrid.) Female mallards have white tail feathers (not easy to judge as the other species are rather pale too, but it's a useful as one factor among others).
speculum: if you see strong white bars on both sides, it's a mallard. Strong black bars, it's probably an ABD (but both ABD and mottled can have thin white bars alongside black).
bill: orangeish (with a brown saddle) is typical for female mallard; olive is typical for female ABD. A strong black spot at the hinge of the jaw means Mottled.
Overall color pattern: male ABD *very dark* on body, with strongly contrasting pale head. Mottled duck like a less extreme ABD, with visible chevron patterns on body and a pale, unmarked underchin - very similar to female mallard.

Mottled vs female mallard: mottled has yellow bill with dark gape spot, brownish tail.

Thank you very much nartreb! That was a big help! I will keep this with me next time I look for ducks!