Beacon Hill Park's lake is a favored spot for ducks at any time of year so I thought I might find something interesting there. While the vast majority are Mallards or Wigeons, after watching for a while I noticed the duck above. This is one of two related species, the Lesser or the Greater Scaup. The major difference is size and the shape of the head. For those reasons I lean towards identifying this as a Lesser Scaup (Aythya affinis). It's called a scaup because it makes a noise like "scaup." The Lesser Scaup is a member of the diving duck (Aythyinae) family. Below are a series of photos showing a dive sequence. Had there been a fourth photo it would only have showed the ripples on the surface since when these ducks dive, they swim around underwater. Dabbling ducks such as Mallards, on the other hand, just tip themselves perpendicularly in the water, leaving their bottoms above the surface.