A few dozen +/- Black Scoters on Lake Wompanoag, in a tightly packed raft (typical behavior of this species).
After spending 20 minutes at Wompanoag, I moved to Crystal Lake for the gull roost and to check for waterfowl. I found a small group of 7 drake Black Scoters, not too far out and snapped the photo below through the scope, in very poor light and with the camera's ISO set to 1600. Also on the lake were ~225 gulls that had come in to roost, those being Herring (135), Ring-billed (75) and Great Black-backed (16). Well after dusk, in the dark, the puddle ducks arrived in numbers, approx. 350 +/- nearly all being Mallards as best I could tell.