Urocissa erythroryncha
At 13.54 on Friday September 9th 2022 I was walking down Pik Shan Path on Lung Fu Shan when I heard a call I recognised as Urocissa erythroryncha, Red-billed Blue Magpie. I photographed a single young bird but was aware of more than one. This is not uncommon. They move around in groups. But then I noticed what appeared to be a carcass hanging in the branches nearby. I checked through 8x30 binoculars and sure enough it was the remnants of a Urocissa erythroryncha. At that point I realised the birds were taking turns to fly in and rip pieces off the carcass. I documented this with still images using a Canon R5 and an RF 100-500mm lens for a period of 5 minutes. At that point the carcass fell to the ground out of sight. This appears to be evidence of cannibalism in the species.
The carcass was already mostly consumed when I saw it. I have no idea how long it had been there but it did not look badly decayed. Just 4 minutes later I spotted an Accipiter trivirgatus, Crested Goshawk perched on a branch above the path and I took quite a few frames of this bird at close quarters. I know this raptor breeds on the hillside and I speculate that the magpie had been predated by a goshawk and the other magpies were simply 'cleaning up'. I have seen feathers of Urocissa erythroryncha on a nearby path before so I am sure they are a prey species of Accipiter trivirgatus. I can't think of any other local bird species that would take a magpie.