I was happily filming a male common darter guarding his territory down Tag Loop today. As other males came across the pond, he would chase them off, no doubt giving them a piece of his mind, before returning to his station on his leaf. Shortly, a new couple arrived, intent on spawning in "his" pond. The female interloper was suspended below her mate as they flew along the edge of the pond, and the resident male was clearly not impressed, so gave chase and drove the brazen couple away......who promptly returned to continue their business.......only to be chased off again. Whenever they were able to pass undetected, the male appeared to swing the female, whilst she made a whiplash motion with her abdomen......together making a movement somewhat like 10-pin bowler casting a ball down a bowling lane towards a set of skittles.....the skittles in this case being the muddy sides of the pond. The "bowling" movement was very fast and jerky, so I may have misinterpreted some of the detail. I'll have a better idea after viewing the tapes.
Another, more bizarre, twist to the story was when the invading couple flew into the resident males territory for the umpteenth time. The resident male gave chase, but on this occasion, the paired male dropped his lady-friend, rather unceremoniously, into the pond and flew off to have a scrap with the resident antagonist. "Ay up.You just wait there love while I go an kick yon fellas 'ed in.........." Just like town on a Saturday night.