Firewood

Fire wood chirping by redchuck
I captured this at home with my Iphone using SoundCloud’s app.  We had a fire going and suddenly I heard birds chirping.  I ran over to the fireplace worried that we were smoking-out a birds nest in the chimney.  Turns out it was the wood… chirping???  Weird.  Can you hear it?  The logs were emitting this warbling, high frequency pitch  that sounded just like baby birds crying for food.   I’ve never experienced that before.  So… is this something that happens regularly when certain types of wood reach a particular temperature or do I have haunted logs?