I’m guessing this bird has been sitting here for two months. With no eggs or mate.
At first there were two, but Great Blue Heron harassed them constantly. Somewhere along this time only one has remained. The Herons are grown and gone now. The Egret stayed.
And then it happened, a new special friend has shown up. Even bringing new sticks for the nest.
I doubt there will be eggs, mating season has passed. The bird on the nest does not even have a green lore marking a breeding bird.
Even so, a happy ending.