Mallard Duck pair show their affection alongside a Lesser Scaup

The setting: a small pond located in a local city park in Milwaukee. 

The characters: One female Mallard, one male Mallard, one male Lesser Scaup, and one male Blue-winged Teal.

The action: coitus.
 
Even though the weather was atrocious, I headed to Humboldt Park to see if any new visitors had arrived. There were two: the teal (a dabbling duck that visits this pond yearly) and the scaup (a diving duck that winters here and is normally seen on large inland lakes or out on Lake Michigan). Of course, I stood around taking pictures, attempting to ignore my quickly freezing fingers and the miserable lighting. 

It paid off. 

After several minutes of watching the teal and scaup, I noticed the mallard pair start to circle each other. Then, they both head bobbed for a few seconds. Before I could finish fiddling with my settings, coitus had begun.

Drake mallards (and I assume other male ducks as well) completely submerge the female during mating, as pictured here: 

A casual observer would not even know that the male was sitting atop of the female. (The scaup seemed oblivious--that's for sure!)

After just a few moments, the female emerged. 

The mallards circled each other again, then each stretched out, seeming satisfied. 

The end.