The Gateway Park duck

[Tony Leukering]

Hi all:

Nick Moore found a Mexican-like Duck at Gateway Park in northeastern Denver County on the 31st. Kathy Mihm Dunning and I went to check it out later that day. Although there were very few ducks present, it took us a while to find it, and it looked quite good for a good male Mexican Duck. It was not very close. Later, when it was a bit closer, I took about a dozen photos of it.

Upon getting back home, I uploaded the photos to my computer, only then noticing that the bird's entire rump (not the tail feathers (!!) -- eBird Checklist - 31 Jan 2026 - Gateway Park - 10 species (+2 other taxa)) was black. That single feature is a death knell for a pure male Mexican Duck. It would also be the same for a pure male Mottled Duck. An entirely black rump is a feature of male Mallard, but NOT Mottled or Mexican ducks, with the latter two having the black rump feathers edged in cinnamon or buff.

Mallard: ML611159207 - Mallard - Macaulay Library

Mottled Duck: ML631488736 - Mottled Duck - Macaulay Library

Mexican Duck: ML428840491 - Mexican Duck - Macaulay Library

Interestingly, the same site had a female Mallard x Mexican Duck, although it's possibly a 2nd-generation bird (known as an f2 hybrid, or one generation removed from the hybridization event, which would be f1), as the bird was quite Mallard-like, but with a bright orange bill with very little in the way of dark smudging on it and with the white borders to the speculum being Mallard-like, but narrower than typical for Mallard. I included photos of both birds in my eBird checklist.

Sincerely,

Tony Leukering

Denver