Some further context might be of value: The OP mentioned that this song was on his old high school tape from the 70s and likely recorded off WBBM-FM or XRT.

Another user also recommended looking into WXFM (Triad Radio), as that is the station that would have played "Rare Bird" back in those days. Though, the archivist for the station was contacted but said he has no recollection of ever playing this song on Triad, nor does he believe it came from that station.