Another photo from the pontoon boat.
Normally we see groupings or rusty blackbirds, this day just one.
It's a start.
Like most members of the blackbird family, the Rusty Blackbird undergoes only one molt per year. The change in appearance between winter and summer results from the rust-colored feather tips of "winter plumage" wearing off and leaving behind the smooth black or gray "breeding plumage."
source - https://www.allaboutbirds.org/guide/Rusty_Blackbird/lifehistory