How to identify owl pellets

February is a good month to see barn owls and short-eared owls quartering rough ground during the day. It is also a good month to look for pellets, the regurgitated remains of indigestible food made by a wide range of birds.

Owl pellets can be told apart by their size, shape and location.

Most owls produce one or two pellets a day, and these are usually found at roost sites. Do not disturb a roosting owl, and remember it is illegal to enter an occupied barn owl nest site without a licence. 

Other birds, such as kestrels, sparrowhawks, buzzards, herons, corvids, gulls and waders also produce pellets, and these provide excellent clues as to what the birds have been eating.

• Tawny owl pellets are grey, cylindrical, around 6cmx3cm with somewhat pointed ends. Often found at the base of conifer trees used for roosting.
• Often contain bird remains in suburban areas. 

• In winter, long-eared owls roost in trees (often conifers) and close to the ground in bushes. Pellets are pale or dark grey, thin and elongate up to 7.5cm x 3cm, rounded at one or both ends.
• Short-eared owls roost on the ground and produce very similar pellets.

• Barn owl pellets are generally found at roost sites in buildings and are characteristically rounded or cylindrical, about 5cmx3cm, with a smooth surface covered with blackish-grey crust.
• The barn owl is the owl most likely to eat shrews.

• Little owl pellets are mostly found in buildings and hollow trees.
• They are very small, up to 2.5cmx1.5cm, rounded at one end and pointed at the other.
• In summer, they largely contain insect remains, so may appear blue-black from the beetle elytra (the hardened outer wings).
• In winter, pellets are grey and contain the remains of mice and small birds. 

• Kestrels nest in holes in trees and buildings; pellets are 3cmx1.5cm, rounded at one end, pointed at the other. They may contain remains of small mammals, birds and insects.
   
• Rook pellets are most commonly found below rookeries and in fields where rooks have been feeding; 3.5cmx1.5cm and generally contain plant remains and small stones. 
   
• Gull pellets generally found at breeding colonies, roost sites and in fields where they have been feeding. Contain fish remains, plant material and remains of fruit and garbage.
   
• Heron pellets usually found at roost sites: variable in shape and rarely contain fish remains. Usually fur of small mammals, especially voles.
   
• Fox scats Occasionally there can be confusion between owl pellets and fox scats: pellets are only found at a roost or perch site, while scats tend to be longer and thinner and often contain some plant material and insects. In addition, scats contain fur or feathers, have a twist at one end, and when fresh, smell of fox.

• To see the contents of pellets, soak them in water and dissect out the bones. Most prey will be small mammals. To identify them, look at the teeth with a hand lens.
• Shrews have continuous rows of small, pointed teeth, whereas rodents have a gap between the front incisors and the cheek teeth.
• The cheek teeth of voles have a zig-zag chewing surrface, those of rats and mice small rounded cusps.

If you enjoyed this article, why not read the previous part or the next part – how to identify mammal scats