Who would be a female Mallard?

On my latest foray onto Wanstead Flats this morning - no I didn't, since you ask - I witnessed what can only be described as a vicious assault. Poor Miss Mallard didn't stand a chance, as five testosterone-fuelled Mr Mallards subjected her to what must have been a terrifying ordeal. I almost stepped in and put a stop to it, but then realised that they were just ducks doing what ducks do, and although in the human world this wouldn't be tolerated (apart from in certain areas of Epping Forest perhaps), in the duck world it's perfectly normal. So I let them get on with it, or with her, and instead took a few photos (which probably also happens in Epping Forest).