“Invocation” pairs a soundscape of birds with a pitch follower. The pitches are created by the computer relative to the pitches of birds recorded at the Pando aspen grove in south-central Utah. The pitches aren’t ‘one to one,’ but the birds create a sonic palette that the computer follows. The music can stand alone as an ambient work or it can be accompanied by spoken word, chanting or art song. It is part of a series of audio and video works called Pando Suite. The piece was produced as part of an artist residency with the non-profit group Friends of Pando.