I understand, the first bird does not give its call when you first click, that is a bug that we are working on right now. If you scroll to the right and then back to the left you will hear that first bird.
My programmer tells me its not hard to make the sound be affected by vertical movement, however it seems to me if you add that dimension you will make it harder to find the bird, not easier. Visualize the sound right now: its like a vertical box around the bird. So you hear it while at the top of the screen or bottom, it doesnt matter. Now imagine adding the vertical dimension to the sound. Now you have a circle around the bird, which means you must get a lot closer to it before you hear any thing. Am I making sense?
Mitchell D Waite