Black Tern

The photo below is a record shot of today's Black Tern found in the tern roost east of the island taken from the Obs balcony with 50x iPhone digiscoping. The head pattern is rather 'White-winged' and the bill looked small when the bird was 'on the deck' although it is slightly turned towards the observers.  However, there is very little contrast between wings and mantle.  

Assuming it was the same bird (two Black Terns were reported off nearby Red Rocks not long after), when seen in flight from east of Middle Eye the bird's wings and mantle appear dark grey and there is a shoulder patch (although not broad). However the tail is distinctly paler (grey not white) than the mantle and wings.  Before anyone asks the flanks were white (see below)! These are very poor ipad screen grabs from iPhone digiscoping video - on the last grab the rump does look whitish but this may be just the quality of the video/grab.  An interesting bird...