This past Saturday morning I birded A. E. Wilson Park, starting at the south footbridge. Cross ing the bridge, I stopped at the island just downstream from it and began pishing. I elicited a rapid response in song that was unfamiliar to me until I saw the singer--an immature male Common Yellowthroat (judging from the greyish mask). I realized then that what I'd heard appeared to be the normal song sung at double speed--Alvin and the Chipmunks version of the song, if you like.
I saw or heard 4 more Common Yellowthroats during my two-hour circuit, but this was the only one that sang.
Can anyone tell me whether the phenomenon I've described is a common occurrence in Common Yellowthroats or in warblers in general?
P.S. I also saw a Ruby-throated Hummingbird (evidently a female) on Boreal Island (in A. E. Wilson Park)
H.D. Sandy Ayer (Mr.)
Director of Library Services
Canadian Bible College/Canadian Theological Seminary
4400 4th Ave.
Regina, Sask., Canada