ID help on Owl Pellet contents please

[KentYeti]

My first attempt at taking an Owl Pellet apart. Almost certain a Short Eared Owl Pellet from where it was found and the fact that it was very fresh, (ie. dropped during daylight on the day I got it).

I've arranged the bones into two groups. Mammal at the top and black shiny ones lower down. Some of that lower group look a bit light, but they are mainly black. Plus some of the fur.

I've added back in the actual pellet to scale. Only I now realise I need to put a ruler in the photo to give the scale!

I think the mammal bones are from a field vole? And with 4 jaw bones I assume 2 of them?

I have read that SOEs kill their prey by crushing the head, which possibly explains the lack of a skull.

The black shiny thing mays have been a beetle or even a dragon fly? I found one small wing attached to a bone. But dropped it and couldn't find it again. Stupid Yeti!

Anyway. Comments and observations from those who know a lot more than me on this very welcome.

Cheers,

Bryan

[Jason Green]

I've never seen a dissected pellet before and never really considered it too deeply. It looks like a good job, and very-well arranged. How long did it take? I suppose the bulk of it is hair from prey-items and from preening, with the more interesting bits inter-twined.

I'll now get out the way to allow for a more enlightened response... I just like to come along and congratulate people on good hands-on work.

[diggleken]

Yes, well said Jason, good work Bryan, I dont know exactly which Owl it would be from, as it looks just like Tawny pellets do too!
Woodman?
Cheers
Ken

[KentYeti]

Thanks guys!

I suppose three or four hours work. Had to photo it with my old Fuji bridge camera on macro and flash, as my birding lenses for my Nikon D7000 don't have/need macro. Well, not until now.

I'm 95% certain it's from a Short Eared Owl. I've watched them perch where I found it. An outside chance it's from the local Barn Owl.

What I need from those who know is if I am right in stating the top left hand bones are from two field voles.

And what type of beetle etc could have been the lower, black and shiny material.

Cheers,

Bryan

[The Woodman]

I'm sure its not a Barn Owl pellet. It's not an exact science but their pellets are usually much darker, have rounded ends and will not normally contain insect remains. Similarly, Tawny pellets do not contain a high percentage of insect remains. Short-eared owl looks probable.

A very useful publication is the Mammal Society's The Analysis of Owl Pellets by Derek Yalden. £3.50

It's not easy to determine vole ID from these images, a close view of the molar groups in either jaw would determine it. Try pulling a molar out with your fingers or tweezers. If the resultant root hole is as big (same profile) as the tooth, it's a vole. If the individual root holes can be seen, it's a mouse or juv. rat.

Also for interest, pull out an incisor by feeding it from it's bone sheath and note how long it is. The root is a long way from the business end of the tooth.

All the fur will be undigested and from the prey animals and compresses in the crop around the bones and other remains. Sometimes there will be bits of gut and odds and ends.


The Analysis of Owl Pellets

p.s. I note you have two separate incisors. As for distinction between Bank and Field Vole there are a couple of things to consider. Adult Field Voles are slightly larger than Bank Voles. The profile of Field Voles molars have jagged sharp zig zagged edges. Those of Bank Voles are more rounded and I always remember them as B (being round edged) for Bank and F (sharp cornered) for Field. I hope this makes sense.

[KentYeti]

A very helpful series of comments. Many thanks Woodman.

I've ordered the book from Amazon and had a very close look at the jaw bones through a magnifying glass. No way will I be able to extract any molars, I do not have that sort of dexterity!

I've tried some real close up shots. They bones are in the same order as in the original photo. Where it seems the top and bottom are from one animal, and the two middle ones from another.

I'm guessing they are all from the same species with the top and bottom ones from an older animal: they are larger and the molars look more worn.

But this is all, totally new to me so I may be completely wrong.

I'm having difficulty deciding if they are rounded or zig zagged!

No, I've clicked on the photo again once it's loaded to get the largest version and I'd say they were rounded. So a Bank Vole?

Any views?





So far as the Owl the pellet came from. It was very moist and I guess very recent from one of the SOEs hunting that area. The only other Owls anywhere near are Barn Owls. I am told there are no Tawnys anywhere near there. No trees!

The second one I have is drier, more rounded and seems to have more bones in it. At least from an outside view. There is also possibly a skull in it. From what you say that could have come from the local Barn Owl. I'll be working on it soon

Cheers,

Bryan

[riggy]

Really interesting thread Yeti and well timed for me as hopefully I am going on a mammal bone identification course on Friday (18/11) if places are still available (waiting for confirmation from organiser as I only found out this weekend I could go). The book woodman mentioned is on my Christmas wish list now along with some others I found on the mammal society website.

Nice set of pics that as given me an idea of what to do with the pellets etc

[Dogghound]

Yes this is from an Asio Owl, rather than Tawny or Barn. Short-eared owl diet consists hugely of Microtine voles (field voles).

They look like field vole jaws as you would expect. Can you get any shots looking down ontop of the teeth (an owls eye view if you like), maybe place them on some bluetac to hold them whilst you photo them.

One of my favourite subjects, if you can find a regular roost and you collect all year, you will find some really interesting things, such as how the diet changes with weather, time of year, change in habitat etc.

[KentYeti]

Originally Posted by Dogghound

Yes this is from an Asio Owl, rather than Tawny or Barn. Short-eared owl diet consists hugely of Microtine voles (field voles).

They look like field vole jaws as you would expect. Can you get any shots looking down ontop of the teeth (an owls eye view if you like), maybe place them on some bluetac to hold them whilst you photo them.

One of my favourite subjects, if you can find a regular roost and you collect all year, you will find some really interesting things, such as how the diet changes with weather, time of year, change in habitat etc.

Many thanks.

Yes, of course I'll have a go at the shots you suggested. Maybe later today as it's a lovely day here and I shall be out soon, hopefully watching a Short Eared owl catching a field vole!

Cheers,

Bryan

PS. Not only is disecting owl pellets a first for me. So is Macro photography. I feel a new Nikon lens coming on! LOL!

[Dogghound]

Originally Posted by KentYeti

Maybe later today as it's a lovely day here and I shall be out soon, hopefully watching a Short Eared owl catching a field vole!

[/i]

Good luck Bryan, I cant blame you. Horrible weather here today.