- Great Horned Owl - Ronald Laubenstein, USFWS
Owls swallow prey whole—fur, feathers, bones, and all. The food goes into the owl’s gizzard, but the stomach acids aren’t able to dissolve solid tissues, so the bird must expel them later through its mouth.
How Do Owl Pellets Form?
After an owl feeds, soft tissue moves on into the intestine, leaving indigestible tissues such as fur, bones, claws, feather shafts, beaks, hard outer parts of insects, sand, and soil. The bird’s gizzard muscles gently mold this mixture into a pellet, a collection of hard objects surrounded by softer material such as fur. Because it represents a single meal, a pellet typically contains the entire skeleton of one or more prey animals.
Muscles push the pellet up into the owl’s proventriculus above the gizzard. In about twenty hours, and always before the bird feeds again, the pellet is expelled onto the ground through the mouth. It is usually sausage-shaped and may be tapered at one end. Its size depends on the size of the owl.
Get an Owl Pellet
The best place to get an owl pellet is from the ground under the place where an owl roosts during the day. The difficulty is finding a roosting owl. Some owls tend to return to the same roost day after day, leaving many pellets on the ground. The pellets of Barn Owls are among the easiest to collect because the birds like to roost in old buildings where their pellets build up and are protected from the weather.
If it’s not possible to collect pellets in the wild, the curious can purchase a pellet from any of a number of suppliers of science kits or birding resources.
Scientific Information From Owl Pellets
Studying owl pellets tells us a lot about the owls and their prey:
- What the owl has eaten. Owls eat small mammals, birds, reptiles and amphibians, insects, fish etc.
- When the owl hunts (some prey species are active only at certain times).
- Where the owl hunts.
- How much the owl eats in one hunting session.
- Whether the owl’s diet changes with season, environment etc.
- Distribution of prey animals.
- Relative numbers of prey animals.
Fossilized owl pellets have revealed similar information about owl species that are extinct.
Dissect an Owl Pellet
Owl pellets can be gently teased apart with needles or tweezers to free their contents. If the pellet is very hard and dry, moistening it with water makes the job easier. Sort the bits and pieces (bones, beaks, feather shafts, beetle parts etc.) into piles. It is often possible to reassemble one or more skeletons of rodents, birds, reptiles etc. and identify the remains by skull and jaw features.
Other birds of prey also produce pellets; however, hawks and eagles don’t always eat the whole animal and their digestive systems break down more of the remains. Dissecting a pellet from one of these birds will not yield such impressive results.
Do’s and Don’ts
A fascination with owl pellets has its risks and dangers.
Do:
- Wear latex gloves while handling owl pellets, and wash hands and tools thoroughly afterward. There is potential to pick up infections from animal remains.
- Be sure that the specimen is an owl pellet, not animal feces. Again, there is a risk to health.
- Store pellets dry and in a well ventilated space. Damp pellets may grow mold.
Don’t:
- Disturb roosting owls.
- Store owl pellets indoors. They may contain the larvae of clothes moths.
Sources:
Firefly Encyclopedia of Birds. Perrins, Christopher ed. Buffalo: Firefly Books, 2003
Kidwings Virtual Owl Pellet Dissection
"Owl Pellets." Royal Society for the protection of Birds. rspb.org.uk
Rosemary Drisdelle - Rosemary Drisdelle has been published many times as a nonfiction writer and several times as a poet. Her first book, Parasites: Tales of ...
