Went out and looked at a lake yesterday and was wondering what kind of ducks I was seeing. I didnt have a camera. They were all black with white on the tail. The underwings were blackish brown. Their heads and neck were a lighter brown. I'm new to duck hunting and am trying to figure out what I'm seeing. We also saw abunch of coot.

long neck?, black bellied whistling ducks?

try googling duck pics. sounds like a gaddy or a molted mallard

It had a long neck. It looked like it may have been a black bellied whistling duck except I never saw any whit on its wings.

could have been fulvous whistling ducks, pretty similar

Not all black. You would be hard pressed to miss the "rust" color on them.

They may have been dark brown but the neck and head was more tan than the body. It kinda looked like they had a patch on the wings like mallards but it was hard to tell. Next time I'll take the camera and get some pics.

Cormorant?

Maybe wood ducks in eclipse plumage?

It was hard to get a good look at them, we forgot the binos in the truck.

Black ducks maybe?

http://sdakotabirds.com/species/american_black_duck_info.htm

They looked pretty close to a black duck but I couldn't see any white under the wing, but I also didn't get very close to them where I could see better.