G call(s) piping from bird on nest, G call(s) harsh series from second bird in flight, G call(s) a few single piping notes from first bird, G call(s) harsh series from second bird now on nest, G call(s) piping of first bird, 2 G call(s) harsh series from second bird, 6 G call(s) harsh series from second bird, G call(s) a few piping from first bird