Last week I gave you this skull of one of our feathered friends to have a go at identifying:

It’s not the easiest one to get down to species level, but everyone recognised it as a something in the family Buteoninae, which includes a variety of hawks, buzzards and kites.

The size is a useful cue to narrow down options – this is especially helpful if you use the incredible resource Skullsite.com, where the skull lengths are usually reported alongside the specimens. The scale here puts the skull length of the mystery specimen in the region of 76-78mm, reducing the options to perhaps half a dozen.

I could offer up my thoughts on how to narrow it down further, but to be honest Wouter van Gestel – a key person behind Skullsite – left a comment that sums it up nicely:

This is a tricky one. A length of 78 mm fits a raptor of buzzard (Buteo buteo) size, and its too large for a harrier (Circus spec) which also are very narrow between the eyes, as is the honey buzzard (Pernis apivorus). The skull is slender and the beak is rather small, which is not a good fit for a goshawk (Accipiter gentilis), which is more compact. The booted eagle (Hieraetus pennatus) has a somewhat bulging forehead, and the Milvus kites have a larger bill. The palate shape is too varied to base an ID on.

The best fit is a common buzzard (Buteo buteo) although the bill is kind of narrow and small. The shape of the lacrimals is helpfull, but they are often missing like in this mystery skull

Wouter’s analysis was spot-on, this is indeed the skull of a Common Buzzard Buteo buteo (Linnaeus, 1758). Wouter’s comments about the bill being a little small and narrow are interesting, as I often wonder about regional variations in morphology, especially for species in Ireland given its location on far western margin of Europe. However, this specimen has no locality data associated on the label, so I can’t be sure where it originally came from, although a little digging may help with that.

I hope you enjoyed this challenge – there will be another next week!