Magpies versus Red Kite

Yesterday morning I saw, high over Eastern Avenue, a red kite being mobbed by a magpie.  The kite was dangling something from its claws: the body of a squirrel, probably road-kill.  The magpie repeatedly approached the kite from behind, cawing loudly, but each time swerving off before making contact.  Eventually the kite let go of the squirrel which dropped down to the roof of the new Red Cross building.  The kite turned towards the north and slowly flew off.  The magpie followed the squirrel down and was joined on the roof ridge by three other magpies that appeared from over a neighbouring building (from where they must have been watching the mobbing from a safe distance).  They all stood there, a few metres from the squirrel, and looked around, as if checking the coast was clear, before, one by one, they hopped down the roof slope to where the squirrel's body lay.