Pied-billed Grebe alarm/contact call
These calls sound very similar to those of some rails such as Sora and the gallinules (Feb, FL).
Pairs duet as they swim towards each other (Feb, FL).
reduced time scale
Quiet calls between Red-necked Grebes (Mar, NJ).
Distant bird in flight (Mar, NJ).
Common Loon, quiet calls between an adult and two juveniles (Sep, ME).