tweedling

Tweedling describes the action of producing a series of light, high-pitched sounds, typically associated with birds singing or someone playing a simple melody on a pipe or similar instrument.

The word suggests gentle, warbling tones rather than bold or forceful sounds.

The finches were tweedling in the hedgerow all morning.

It can also describe idle, aimless activity with instruments or, figuratively, fussing with something in a trivial way.