Thank you Annastrophic, most current Ivory Bill site on the net.

I couldn't get the link to the double knock calls to play but I'm sure that after 18,000 hours of listening for bird calls their fix on the distinctive sound must be convincing. (Although 18,000 recorded hours of studied sounds from the deep Arkanasas woods would probably yield up bird notes that score the national anthem.)

It would be a sad day indeed if when the study is completed in 2007 it is concluded that the Ivory Billed Woodpecker is no longer extant.

What a magnificent bird it is...or was.