try to use “move to location” node ,it allows you to move the birds in the air,and doesn’t need a navmesh.
And use “random unit vactor” to generate a random direction,then use that direction to fire a line trace(also a random length in a wanted range).and then if it hit something means that the the location is on the ground,we need to regenerate new location again. only when the line trace has hit nothing,we can use the line trace’s end location for the target location.