Whilst on a guided visit to Mai Po with Martin Williams he pointed out an Egret getting close to a next of a pair of Black-winged stilts. The male stilt was clearly not happy with this and began harassing the Egret, trying to scare him off.
The Egret ducked under his own wing for protection.
In this next image, you can see the female sitting on the nest at the far right middle of the photo, whilst the male keeps up his assault.
It appeared that the Egret still thought he had a chance, and he kept moving towards the nest, so the female joined in the assualt.
The stilts were more and more agitated, and what were close buzzing swoops turned into a hit with the legs.
Soon after this the Egret walked away from the nest and the stilts settled back down to their feeding and nest sitting, ever vigilant for the next attack.