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Dissecting owl pellets

Gemma Waters is a natural history educator in Hampshire, running hands-on activities with schools and other groups. Below she tells you all the gruesome facts about owl pellets, and how you can dissect them yourselves! Great!!


My job is great! After teaching in natural history museums, I decided to start my own business - Natural Selection Learning. I visit schools, colleges, museums and community centres with my collection of fossils, insects and bones, to help children and adults discover more about the natural world.


One of the group activities I run is an owl pellet dissection – a chance to find out what owls eat and how! With my trusty sidekick Hector the stuffed tawny owl, we hope to show people that pellets can be really interesting and not at all gross… well, only a little bit.


‘I can’t believe you’re going to make us touch bird poo!’

 

That’s a common reaction when I tell a group we’re going to work with owl pellets. Even some of my friends look at me with concern when I say I’m off to run a pellet workshop. They needn’t worry though - owl pellets aren’t actually droppings, but the undigested parts of an owl’s prey (such as fur, teeth and bones), ejected through the mouth. By looking at the contents of pellets, we can get a really good idea about what owls are feeding on in particular area.

Owls consume prey such as mice, voles and smaller birds whole. When the prey reaches the first stomach, digestive juices start to break down the soft tissues. After this, the partially digested remains enter a second stomach called the gizzard. Here, the indigestible parts are compacted into a sausage-shaped pellet, which hours later, is pushed up and out of the beak!

Examining an owl pellet is a simple and fun natural science investigation you can do at home, and you don’t necessarily need any specialist equipment, just things you’re likely to have around the house. However, it’s important to remember pellets can carry harmful bacteria, so always handle them with gloves and make sure they are kept away from food and drink.


Getting to the nitty gritty

I usually soak pellets for about half an hour before a dissection. This can make them easier to take apart, especially if they’re fairly compact. Older pellets can be crumbly so may not need soaking. A clean yogurt pot or similar, with a few drops of clear disinfectant works well. The pellet can then be placed on some newspaper or a paper plate, ready to be examined.

The first thing you’ll probably notice is if your pellet is mostly made up of fur or bits of feathers – a good indicator as to what bones you can expect inside. Carefully use tweezers to pull the pellet apart and begin removing the bones. Take your time; the bones can be very fragile and can easily break, making identification difficult. Cocktail sticks make useful tools for removing fur from eye sockets and joints. Use a bowl of water to give each bone a quick rinse, before drying them on a piece of kitchen roll. A magnifying glass or microscope, if you have one, is also useful.


Identifying your finds! 

A chart will help you start to identify the different types of bones you have found (there are plenty available to download online). However the skull, jaw bones and teeth will provide the biggest clues. For example, vole molars can have vertical ridges and when viewed from above, appear to make a zig-zag pattern in the jaw.

You will often find the remains of more than one prey animal in a single pellet. Try counting up the number of skulls and pairing up left and right jaws bones.

In addition to bones, some pellets may also contain tiny bristles from earth worms, beetle wing cases (elytra) or even clothes moth caterpillars. Clothes moths lay their eggs in owl pellets and the caterpillars eat the fur!

If you want to keep your bones, try arranging them on a piece of card to show the skeleton of the prey animal, then glue them in place ready for labelling. When you’re finished, make sure you thoroughly wash your hands and disinfect all the surfaces you’ve been working on.

To find your own pellets, try looking on the ground around roosting sites (it’s important to remember not to disturb any owls. Barn owls are protected in the UK). The Barn Owl Trust also sell pellet investigation kits on their website.

 

To find out more about Natural Selection Learning see www.naturalselectionlearning.co.uk

Or find us on Facebook (www.facebook.com/Naturalselectionlearning) or Twitter (@NS_Learning).


Take a look at our Wildlife Watch activity sheet, which tells you all about dissecting owl pellets!


Download it here! 


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