Siskin aggro

Interesting to note how intolerant the male siskin (back this morning) is of other species on the feeder. He breaks off feeding to use threatening behaviour - wing-fluttering, beak open, even with his mouth full - towards members of the tit family. Even the great tit, normally second only to nuthatch in the pecking order, seems quite cowed by this. Not so the nuthatch, it's the siskin's turn to be intimidated as the nuthatch gives him a hard stare. 

Presumably this is post-breeding dispersal?