Out of curiosity, not being a wind player myself, how do you "pitch bend" on an Irish whistle? I've always wondered, and find the effect rather delicious to hear.
You partially cover the finger holes on a whistle, sort of rolling your fingers over them, or sliding them on or off the holes. It becomes second nature fairly quickly.
On a flute, you can do the same, but you can also bend the pitch a fair degree by changing the angle of the airstream across the aperture.
I thought it was something like that, but not having the proper instrument may have thwarted my rather amateurish attempts to do the same with other wind instruments.