von Humboldt

The last pic makes me comfortable in saying it's male

Not sure but I think its a male. The bill is more yellow than green and you would expect male Mallards to be hanging out together this time of year.

Have to be

The bird in the second photo is a male Mottled Duck. Yellow bill make it a male and Buffy cheeks, short eyeline, gape spot and under tail coverts look like a purebred Mottled Duck. The other duck has a weird bill. It's hard to tell the color of the bill and the shape is hard to discern due to glare but the plumage looks like a Mottled Duck. Maybe it's the female Mottled Duck and just has a large deformed bill or the lighting is making it look so.

It may be that other Cardinals are also using the feeder at a particular time of day, but you do not realize it because they are not distinctive looking. Birds tend to be creatures of habit when they have safe habitat and a food source. Mites are fairly common in Cardinals and their head is apparently a vulnerable area as I've seen several that were nearly bald during my life. If it continues to regularly come to your feeder you'll probably notice that the feathers grow in over the next several months even if it's not the time of year for a molt..

Female Cardinal with feather mites.

I agree with Pharlarope - those wings just don't look like they belong to a dove.

Domestic Mallard

The eyeline is very long and the tail coverts too black for it to be pure Mottled Duck. It has to have some Mallard genes in its ancestry. I don't know if the white spot on its chest is feather, trash, or artifact. If it is white feathers there might be some domestic Mallard genes.

I doubt that male Cardinal was molting. Cardinals are notorious for having mites and losing patches of feathers, usually around the head. They're definitely pretty ugly and can remain bald for weeks. As I am sure Tony's articles point out, molting is a replacement of feathers. It is not losing the feathers so there are bald spots and then having other feathers grow back in. The above picture of the goldfinch shows the classic appearance of molting – where you can see both types of plumage with patchy areas of the old and new plumage. ETA: some female birds do get a bald spot called a brood patch during incubation for egg warming, but I don't think its relevant here

As could be expected, Tony Leukering is exactly right. A gape spot is clearly visible in these photos and the better coloring shows the tail is not as white as I thought.

Tony Leukering knows more about Mottled Ducks and their crosses with Mallards than anyone in the country, so if he says it is a Mottled Duck then it's a Mottled Duck. But being argumentative and curious I must ask, shouldn't we be able to see some indication of a gape spot even with the severe overexposure.

I believe that is a male Mallard X Mottled hybrid (with probably more Mottled duck than Mallard). The tail has Mallard characteristics, and the head and chest look like a Mottled Duck. The bill shows no black which would be highly unusual for a female Mallard.

In the early 2000s I saw a very leucistic Red Tailed hawk for around five years on my farm. I only knew it was a red tail hawk for sure because of its mate. At that time I did some research on leucistic birds and read that, although still very rare, Robins and red tailed hawks exhibit leucism more often than other birds. I've seen thousands of robins in my 60+ years but have never seen a leucistic one in person.

Yes, juvenile blue morph