A Deceit of Lapwings

I was just strolling along, minding my own business, in the sunshine when suddenly all these Lapwings took flight from the lake........it was an amazing sight as the sun caught the white patches and made them appear to sparkle like daytime stars ( unfortunately a photo just can't show this). I zoomed back as far as my lens would allow, to try to show just how many there were ( see extra)........but as you can see there were so many I just couldn't fit them all in  :-) I have no idea why they were doing it, they just seemed to fly this way and that, with no apparent purpose...........I guess they did it just because they can :-))

I had to look up the collective term but I don't like it much..........I'm sure Lapwings are not deceitful :-/