After goldenrods bloom, they dry out and produce fuzzy clumps of seeds along the flower stems. The individual seeds are small and have silky parachutes attached so that the wind will disperse them. I think the plant above is one of the Tall Goldenrods I identified at the site of the former marina. Here is a photo of one in bloom from early October.
When I walked through the marina yesterday morning, I did not see or hear many birds at all (unlike last week). The most notable bird was an Osprey that flew back and forth along the river.