Friday mystery object #216 answer


Last Friday I gave you this mystery sternum to identify:

mystery216

I had a rough idea of the family, but I was less certain about the species. As it turns out I’m now less sure of the family than I was before, in light of some useful comments.

At first I thought this was the sternum of a member of the Strigidae or the ‘True Owls’ – something that Jake also thought with his suggestion of Tawny Owl Strix aluco, but henstridgesj and Daniel Jones raised the possibility of it being from a seabird and Daniel Calleri suggested it could also be from a member of the Halcyonidae or the ‘Tree Kingfisher’ family.

With the Christmas and New Year break I haven’t had a chance to get to our stores to check specimens, but there is a very useful website that deals with seabird osteology (helpfully called Seabird Osteology) which has some images of sterna. Several of the Procellariiformes (the order containing the Albatrosses, Petrels, Shearwaters, etc.) have a similarly short sternum with a double notched bottom margin, as do some of the Laridae or the Gull family.

I also checked an image of a Kookaburra from a previous mystery object, which doesn’t show the sternum well, but which does hint at a double notched bottom margin:

Laughing Kookaburra Dacelo novaeguineae skeleton

Laughing Kookaburra (Dacelo novaeguineae) skeleton

This has left me slightly less confident that last week’s mystery object is from an owl, but here are a couple of other owl sterna for comparison:

Barn Owl Tyto alba sternum and coracoid

Barn Owl (Tyto alba) sternum and coracoid

As you can see, the Barn Owl sternum above doesn’t quite have the double notch, although the size is about right. The Eurasian Eagle Owl sternum below (ignore the coracoids and other bits of the pectoral girdle) is a much closer fit, although substantially larger.

Bubo_bubo_sternum_coracoid

Eurasian Eagle Owl (Bubo bubo) sternum, coracoid, furcula and scapula

I’ll see if I can find a Tawny Owl sternum to check against, because the shape does seem pretty good for one of the Strigidae and the size is about the same as a Barn Owl, which is in a different family, but has a size range that overlaps with the Tawny Owl. Of course, it could also be from one of the other medium sized owls, like the Long-eared or Short-eared Owls… more to come!

UPDATE 14:30 on 3rd January 2014

Here’s a Tawny Owl sternum!

Tawny Owl (Strix aluco) sternum

It’s pretty close, but the notches seem a bit deeper, so perhaps one of the Asioninae (Eared Owls) might be a better match for the mystery object?

7 thoughts on “Friday mystery object #216 answer

  1. How do you begin to identify a bone? Sorry, this is a random question, but if have been reading your posts for a while and I keep wondering. What is the thought process you use to identify bones?

    Also, what are some good books to read to become better at identifying bones?

  2. Too bad I missed this one last week, birds being my favorites. Maybe I can put my E 0.02 in afterwards.
    I have hundreds of bird skeletons, but unfortunately the organization of my collection is a bit behind schedule, so I cannot check everything right away. Some suggestions I could look into and exclude: kookaburra, woodpecker and shaerwater all have sternums that are not similar to this one. Luckily, I have a mounted skeleton of a short-eared and a long-eared owl mounted together at the same stand (too bad I cannot add pictures to this message) so I could check those out. Take into account that your specimen is a bit worn at the edges, and the fact that the shape of the distal end of a sternum often shows some variation within a species, I can say that an eared owl is a pretty good match, and the long- eared looks closest to your specimen.

    With best wishes for 2014, Wouter

  3. I got to this late also, but enjoyed the search. The closest thing I could find was the burrowing owl, Aethene cunicularia, but it was about .5 cm shorter and wasn’t an exact match, but closer than anything I had access too. I only have N. American species.

  4. Pingback: First ever tawny owl on Ameland island | Dear Kitty. Some blog

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