Yellow-green Vireo at National Butterfly Center, 6/24/15

I'm a little late in posting this one.  The spring and early summer has been great for butterflies so I was checking them out at the National Butterfly Center when I distantly heard the "viree-ee...viree-oh' song of a Yellow-green Vireo.  I chased it down several times before I finally got some poor shots of it in the tepaguajes west of the bird feeding station.  A couple of other birders got to see it but it was never reported again.  Since then another was photographed at Quinta Mazatlan and a third at the more expected Resaca de la Palma.