I made several quick stops at Black Hills/Little Seneca Lake this afternoon.  
There were no large numbers of anything, but some special sightings.  First, 
from the RT 121 parking area facing the dam and visitors center:
the pair of eagles flew into the "eagle tree" and vocalized quite a bit, then 
flew off again.
6 common loons, all male
6 or 7 dc cormorants, including one juvenile
2 groups of bufflehead, each with 1 male and 3-4 females
a flock (at least a dozen) of tree sparrows, mixed m/f, skimming the lake

from the same area, looking west over the lake:
3 pair of horned grebes, with the males in full breeding plumage (wow!) they 
were very close to the road
another 2 cormorants

at the boat ramp area within the park:
1 m and 3 f ring neck ducks
12 or so canada geese
small group of coots
pied billed grebe or two
the resident domestic geese pair
4 more cormorants

then, at the same spot, I was scanning the dead trees for woodpeckers, and 
saw a female wood duck in the top of a dead snag.  She was tucked in and 
I'm assuming sitting eggs.  

other than feathered creatures around the lake, I saw evidence of beaver 
activity, namely what was left of a 4-5inch in diameter tree and a beaver-
lodge-under-construction on the opposite side of the inlet.  And two kids on 
their last day of spring break catching sunnies.