Most birds produce pellets. Pellets contain the parts of a meal which a bird is unable to digest. Instead of passing through the birds digestive system and out of the back end, these bits are coughed up in the form of a sausage-shaped pellet.
You're probably wondering just what delightful treasures can be found inside these lumps of bird puke. Well wonder no more my friend because we've dissected one here for you. These photos show you exactly what to expect when you take apart the pellet of a barn owl.
This shows what barn owl pellets look like. I know they look like something else, but you'll have to trust us on this, they are barn owl pellets.
To make your pellet more open-up-able (technical term) you need to drop it into a container of warm water. An old disposable food container is ideal for this.
The pellet is glued together with bits owl spit and puke, so if it doesn't fall apart straight away, try teasing it apart with a couple of cocktail sticks. The sticks will be handy for sorting bits out later (but not for serving snacks or cherries).
Next drain off the water. Just pass it through a piece of netting or a bit of strong kitchen paper (not your mothers/wifes favourite kitchen sieve). After draining you'll be left with a soggy mess like this.
Use your cocktail sticks to tease the remains apart, and separate the bones from the fur. This can be a bit tedious, but the tedious bits are interspersed with good bits, like finding a skull or two.
Here are skulls from a shrew (top left) and a field vole (top right). Not sure what the round skull bottom left is, but it's either a very small vole or a bat.
I guess if you've got a bit of time and a lot of patience you could reassemble this lot. Just remember to wash your hands afterwards.
Note that owl pellets very often contain the eggs or caterpillars of clothes moths, so if you bring pellets indoors be careful the adult moths do not emerge.