at the park on Halloween

Today when I went down to the park, it was partly cloudy. When I was on the breakwater, I saw some seagulls, shorebirds, two ducks and one female goldeneye. When I was by the science center, I saw a raven. When I was near the park, I saw a bunch of goldeneyes out on the water. When I was in the park, I saw and heard a raven, some kinglets and a squirrel in the trees. When I was at the battle site bench, it was almost high tide and I saw some seagull by the water. When I was by the trail by the river, I saw a lot of seagulls out by the other side of the river. When I was on the trail by the river, I saw some ducks and a merganser on the other side of the river. When I was on the trail by the foot bridge, I saw some mergansers fly up the river. When I was on my way back home, I saw a thrush.
Why was there only one goldeneye by the breakwater?
Why did the mergansers fly up the river?
Why was the group of goldeneyes by the park?
Happy Halloween!