This is a lowpoly chirping bird whistle I designed in Fusion 360 to be printed without supports and sagging. It's designed to be best printed in the default orientation of the STL. There is an internal baffle that reduces the amount of water required for the chirping effect.

To get the whistle to “chirp” put in a little water through the whistle hole at the top of the birds head. If printing with a clear materal, the water should go up above the baffle. See attached diagram. 

I print with 0.6mm nozzle at 0.24mm layer height.

Please play around with the amount of water you add, specially if you print in an opaque material.