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Dissecting bird pellets


It can be difficult to bones of even quite big animals like foxes or deer, so you might think it's impossible to find really small bones, like those from voles or mice. In fact it's easy if you can find bird pellets and over the spring and summer I collected loads in the woods. Some of them were from walks that dad did alone when I broke my leg like the one with the trapped roe, and others were ones I found myself, like on my one-hour challenge. A good place to look is in pine forests, or at the base of trees at the edges of fields.

I've written about pellets before and at the time I thought owls were the only birds that left them. In fact loads of birds spit them up, like raptors, herons and crows. What happens is that a bird eats its prey but it cant digest the bones or fur which stay in its stomach. Later on it vomits them up so it spits them out with the fur. Anyway, I has a close look at nine pellets and this is what I found....

If you've never seen an owl pellet they often look like this: dried balls or bullet-shaped balls. It they look too long and thin, though, they might be fox poo. I've picked apart some of those by mistake !

Pellet #1

Size: 6.5 cm long x 2.5 high
What it looks like: circular, shiny on bones surface

This is what it looked like when dad first found it. This picture was useful to show how shiny it was when it was found, because it was dried when I looked at it later:

Even before picking it apart you could see bones in it. This is the head of a tiny femur (thigh bone):

This was one of the jaws in it.

I picked it apart in a dish using cocktail sticks then rubbed the fur between my fingers to find bones. It had loads:

This was what looked like a small rodent vole(*) skull

There were five vole(*) skulls in the pellet, all of which had been crushed in the back of the braincase.

There were six halves of tiny pelvises: (each of those lines is 1mm)

This was a lower jaw from a shrew.

There were the eight mandibles from what looked like mice voles(*):

And a load of leg bones too:

What I think it was most likely from: My best guess is that this pellet came from a barn owl.

Pellet 2

Size: 5 cm long x 2 high
What it looks like: It was long, rough and it had bones on the surface
What was in it: 3 skulls, 4 big jaws and one small

These were the two skulls, they were partial like the ones from the first pellet:

There were 4 mice vole jaws( the big ones ) and a shrew ( the small one ).

What I think it was most likely from: I think it was from a carrion crow. "Tracks and Signs" says rook and jackdaw pellets are smaller.

Pellet 3

Size: 4 cm long x 2 cm high
What it looks like: It was ball shaped and it had bones on the surface

What was in it: 3 vole jaws.
What I think it was most likely from: barn owl

Pellet 4

Size: 5.5 cm x 2 cm
What it looks like: Long and thin
What it could be from: Grey heron, buzzard or short-eared owl
What I think it was most likely from: Short-eared owl.
What was in it: 2 vole skulls, 4 vole jaws, 2 pelvis halves 

Pellet 5

Size: 5 cm long x 2 cm high
What it looks like: Long and thin
What it might be: short eared owl, tawny owl, buzzard
What I think it was most likely from: buzzard
What was in it: 1 vole skull, 4 vole jaws and 2 pelvis halves

Pellet 6

 Size: 4.5x4.5cm and about 1cm thick
What it looks like: Rough disk, flat and bones on surface
What was in it: 2 vole skulls 3 vole jaws and 4 hips 

This is my dads foot next to it

These are the jaws from it. I think the left and right ones were a pair:

There were two skulls:

These where the extra bones - I can see tibias, femurs and an ulna - and a rabbit vole incisor (the banana shaped one):

What I think it was most likely from: I don't know ! Do you ?

Pellet 7

Size: a 2cm wide ball 
What it looks like: It was small ball shaped and no bones on the surface
What I think it was most likely from: Possible kestrel
What was in it: 1 skull 2 pelvis halves and 4 jaws 

Pellet 8

Size: 3cm x 2cm x 2cm
What it looks like: it was smooth and flat
What it could be from: Hobby, sparrowhawk or partial buzzard pellet
What was in it: One skull, two jaws and leg bones

What I think it was most likely from: Buzzard. I haven't seen any hobbys in the area and sparrowhawk pellets don't usually have bone in them.

Pellet 9:

Size: 3cm x 2cm
What it looks like: small and fluffy
What I think it was most likely from: fox poo ?
What was in it:  vole bones

I find it easy to identify the bones in pellets, but hard to identify what bird the pellets came from. Do you think I got them right ?

(*) Thanks to Ric Morris who in the comments pointed out my mice skulls were voles ! I've corrected the piece

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Ric said...

Hi Jake - like you, I struggle a bit to identify the birds that produced the pellets. It's always brilliant to pull them apart, though, you never know what you'll find. One thing though - all your 'mouse jaws' are actually from voles. All the rodent skulls shown here are voles too. I haven't seen any obvious mouse remains in any of the photos.
All the best

Jake said...

Arghhhh ! Thanks, I've changed my mistakes in the piece.

Psydrache said...

Owl pellets are cool! But pellets of buzzards and similar birds of prey doesn't have a lot of bones inside. Ofter there is only fur. Owl pellets have always bones inside.

Jake said...

Do you think I identified them correctly then ? The first one I'm pretty sure was owl and had loads of bones in, the others didn't have as many.

Christine Sutcliffe said...

I found some pellets when on a hillwalk recently. I brought them home to dissect but I've somehow managed to misplace them which is a pain as I've never actually had much luck in finding any til now! I think they were from a Buzzard or smaller bird of prey though as they were very fluffy and I couldn't see any bones on the surface.

Ric said...

Oh - and I think the rabbit incisor is probably a rodent too, looking at the size comparison with the long bones. If it's actually from a rabbit it should have a groove right along the middle of the outside edge.

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