Using the boundary capsules. These gave a nice wide stage with

many sounds spread out from left to right.  However this sound stage
also includes a large number of sounds from the rear.  Typically if I
heard an interesting call on the right I would move my head to the
right to look for it.  I then heard the sound even further to the
right as I had not moved the microphone, only my head.  Ideally I
should have kept my head still and searched with the microphone. 
However the boundary section of the mic is very much omnidirectional.