Nesting robins

Last week I gave the forsythia a bit of a trim. I remembered that robins had nested several times in the first one of the group along the back fence, and I was hoping to get the trimming done in case they were planning to return.
This morning I saw two robins flying to this bush from different directions, each with a strand of nesting material. A scraggly beginning of a nest is barely visible inside the bush. They are definitely back, reminding me of more things I don’t know. Why this bush, when there are four others? Are the same robins returning every year? Or do robins in general view this as a particularly desirable location?

Location:Maryland