Last week we had these two skulls from Andy Taylor, FLS to have a go at identifying:
Everyone recognised that these are the skulls of Tube-nosed birds in the Order Procellariiformes – very large Tube-nosed birds.
Usually, you’d think of albatrosses when considering large Procellariiformes, but they have proportionally longer bills than this and while they have the nose-tube characteristic of the group, the tube is quite small and to the sides and rear half of the bill. In the mystery specimens, the tube is large and located on the top, and in the front half of the bill.
As Wouter van Gestel recognised, these skulls are from Giant Petrels in the Genus Macronectes. They actually represent both species in the Genus – the top one is the Southern Giant Petrel Macronectes giganteus (Gmelin, 1789) and the lower one is the Northern Giant Petrel Macronectes halli Mathews, 1912.
They’re quite hard to tell apart, and the best feature I noticed for distinguishing them is the shape of the palatine, with the Southern having a very gentle curve to the rear section – as indicated below (in a very rudimentary way):
Andy has already written up some information about these birds on his Instagram account, which is well worth checking out:
Thanks for all your observations and thoughts on these rather impressive specimens!
Zygoma 
Thanks a lot for this interesting info how to tell these two species apart. In mij collection I have several Southerns (with a lot of variation within the species) but no Northern, so I could not make a direct comparision. A friend of mine has a Northern in his collection (which I’ll try to borrow for the next photo session of Skullsite) but I had only a sideview picture of it.
What is Skullsite?
OMG! You’re in for a treat! Check out skullsite.com for the best online bird skull reference collection. It’s run by Wouter.
Thank you!
Thanks a lot for this interesting info how to tell these two species apart. In mij collection I have several Southerns (with a lot of variation within the species) but no Northern, so I could not make a direct comparision. A friend of mine has a Northern in his collection (which I’ll try to borrow for the next photo session of Skullsite) but I had only a sideview picture of it.