von Humboldt

The first sentence should read "The upper left duck"

The upper right duck is a male (yellow bill). You can see that the tail feather has a very slight upward turn. This means there are mallard genes in its ancestry as a mottled duck's tail feathers should be straight. The gape spot is not a real good identifier for pure mottled as most hybrids have them. A small deformed gape spot is usually an indicator of mallard ancestry but a perfectly formed one does not mean it's pure mottled. The female appears to be rather light-colored but that's probably just the sun. There really needs to be a photograph directly from the side so you can clearly see the gape spot and the length of the eyeline . This one appears to have a short eyeline which would indicate pure mottled. The eyeline length is one of the better indicators of a pure mottled as they stop just behind the eye and a mallards almost reaches the dark feathers on the back of nape.

Assuming they're smaller and short neck, stubby bill at an angle to the forehead means Cackling.

I feel comfortable calling that a comic book ivory bill.

agree

While it's too blurry for a positive identification. Two of the ducks, in the lower right-hand side of the photo, are so small they must be green winged teal.

The two birds in the first picture are definitely mallards. The one on the right with the yellow bill is a male in eclipse plumage or possibly a juvenile. The second picture – the three birds in front are mallards as you can clearly see white tails on all of them. I'm unsure of the bird in the back as you cannot see the tale or shape due to the shadows and the bill sure looks solid black. It's probably a female juvenile mallard whose bill is just starting to turn, but I can't eliminate teal. Maybe others can point out something distinctive in that bird to say why it is a mallard.

then they are California.

I believe you can see enough red on the on the forehead to say it's a male red-bellied.

Agree they're mallards. They're going through eclipse plumage and that's probably what's making them look odd to you. Definitely males with that bill color. The bills not as bright now as it will be in the winter and especially spring breeding. The one on the left may be a first year duck as his bill does look pretty drab.

Charlie, I see orange legs and I believe a hint of a speculum, so I'll have to respectfully disagree.

I let them live in my chimneys since I moved out into the country 30 years ago. Watching a large flock of swifts circle and circle a chimney for 10 – 15 minutes then enter the chimney is one of the great sights in birding.

I can't hear your file but those are almost surely just hatched Chimney Swifts. I don't know of any other bird that hangs out in chimneys and this is the time of year for the young to be crying for food. The adults have been in the chimney longer than a couple of weeks but they don't make near as much noise. Go outside and watch the top of the chimney about 30 minutes before sunset until near dark and you should see adult Chimney Swifts entering.

I agree these are juvenile mallards just coming into adult plumage and bill color. Probably all from the same brood due to behavior and apparently being the same age.

Nice gape spot + short eyeline. Very thin white bars on speculum. I agree it's pure mottled duck. The light coloration on the tail is due to wear this time of year and is not a true white like a female mallard would have. Also, in Florida the female can have a bill that is anything from dull olive to indistinguishable from a female mallard.