Wimbledon Common: Cootling Tousling

More aggressive parenting in large
Extra: Considering approaching

I met a friend for coffee at the Windmill Cafe on Wimbledon Common, but visited Queensmere Common briefly beforehand. There was a mandarin drake on the pond, and a pair of coots with a batch of little cootlings.
This parent was punishing a dominant chick by shaking it by the head ("tousling"); it is hypothesised that punishing larger chicks that beg persistently reduces their ability to monopolise the parents' attention, resulting in more balanced feeding of the whole brood (leaving parents that punish dominant chicks with more surviving chicks overall). The behaviour can get pretty frenzied, and chicks sometimes die when shaken repeatedly by a parent. They don't tousle chicks from day one, but this behaviour increases as the chick ages to prevent the larger (earlier-hatching) chicks from outcompeting their younger/smaller siblings.

Others here (or right from Mandarin drake)