Gulls Just Want To Have Fun

I walked round Seventy Acres Lake this morning and met some lovely dogs including Reg the Rotty/boxer and Vern the Weimaraner.

Before I left for home I stood on the decking overlooking the lake. I noticed a large gull tussling with some crows. Then it harried a heron flying over the reeds and was causing consternation among the black-headed gulls. It was very distant but I thought I saw it pick something out of the water. I guessed food, though probably too early in the year to be a chick. 

A black-headed gull followed it squawking away. The larger gull then repeatedly dropped and caught the object in flight. It did this at least seven times. I got shots even though I couldn't see what was happening with the naked eye.

I think the object was a stone. I've seen online that gulls do like to play in this fashion. I believe the bird is an immature herring gull.