Common tern movement at the flash

There was a largish movement of common terns at the flash this morning. First off I was walking along the canal when I heard the calls of terns and watched as an adult and two juveniles flew right over my head and away over the ruck, before dropping down towards the spit but then thought better of it and climbed again and continued south.

Then 30 minutes later, in scenes reminiscent of that incredible day of little gull passage at the flash last April, 18 common terns dropped out of the sky, flew around the spit for two minutes and then climbed high and headed south. A really exciting experience. As far as I could tell they were all common terns but it can be quite difficult to be sure with a group of such active birds. 

One thing I can say for sure, they were all adults, which is a bit odd. Common terns do build up at this time of year at the flash but they're usually family parties. What this means is uncertain, but I guess that chances are they are all non-breeders.