How to identify older ducks

[tiffanycobb]

I have some older ducks. I'm not sure what breeds they are. I'm pretty sure one is female mallard and one is a buff. The other two I'm at a loss. Any help is appreciated and how where do you go to identify your brood?

 

[chickens really]

First on is Cayuga the second one I cant remember the name right now....The third is a Khaki Campbell and the last one is a Buff....Nice Ducks....

 

[LilJoe]

#2 black swedish

 

[learycow]

Buff (very lightly colored one)
Khaki campbell (chocolate brown one)
Black Swedish (black with white chest)
Cayuga (all black)