An American Robin (Turdus migratorius) sings an overture of Spring vocalizations in this mid-March, 1998 recording. Just about every voice and call a Robin can make, he makes in this sample. The session lasted over 20 minutes, so I've compressed this to demonstrate all the different sounds he uses.
Here's a short sample of what a Robin convention sounds like. This gathering was held at Red Tank Draw, in Central Arizona, 12/26/98. There were over 1000 American Robins there that day, all eating Juniper flowers and bathing in the red rock creek.