Ages - Get to Know

GRAB N’ GO ACTIVITY:
Dissecting Owl Pellets
OVERVIEW:
This is a hands-on activity that will give your students
wonderful insights and tactile experience with owls
and what they eat. Your students will handle actual
owl pellets, dissecting them to determine what foods
owls have eaten.
As a precaution, owl pellets are sterilized before
shipping to schools, so they are generally safe to
handle without gloves.
However, if any of your students are allergic to animal
hair, they may have a reaction to owl pellets, and may
be required to use a dust mask. You can also provide a
plant sprayer to mist the pellets occasionally, which is
effective at keeping dust confined to the tabletop.
The owl pellets your students will dissect will likely
have the bones of several mice in them, and possibly
the remains of other organisms. Most commercially
supplied owl pellets contain mouse bones, and we
will assume that in this activity. The best indication of
how many mice might have been incorporated into
the pellet will be the number of skulls that can be
found in a single pellet.
OBJECTIVES:
• Gain insights into the diet and biology of owls
through an analysis of the contents of an owl pellet.
• Develop a better understanding of mammalian
skeletal anatomy based on remains recovered from
owl pellets.
Ages:6+
Time: 40 - 60 minutes
PRIOR KNOWLEDGE:
The more your students know about owls before
doing this activity, the more they will enjoy and
benefit from it. We recommend building up your
students’ knowledge and appreciation of owls
through any of the following activities:
•Divide your class into groups and give each
group a one-day assignment, to find an image
and basic information about a species of
owl found in Canada. Have them locate this
information on the Internet, and make a onepage report that includes:
• A photo of the owl.
• Where the owl lives.
• What the owl eats.
• Details about the size, markings, and
physical features of the owl.
Here is a list of owls found in Canada:
-Boreal owl
-Screech Owl -Snowy Owl
-Barred Owl
-Hawk Owl
-Great Grey Owl
-Great Horned Owl
-Barn Owl
-Spotted Owl
-Northern Pygmy Owl
-Short-eared Owl -Burrowing Owl
-Long-eared Owl
-Flammulated Owl
-Northern Saw-whet Owl
Have your students compile these reports into a
booklet they can copy for each member of your class.
Get to Know Program • 201-2040 Springfield Road. • Kelowna, British Columbia • T: 250-980-3969 • E: [email protected] • gettoknow.ca
GRAB N’ GO ACTIVITY:
Dissecting Owl Pellets
WHAT ARE OWL PELLETS?
Owl pellets are neat little packages of fur, bones, and
other indigestible stuff that are regurgitated (spit up)
sometime after an owl has finished digesting several
meals. You can find owl pellets on the ground under
trees where owls like to roost or nest.
All owls cough up pellets as a part of how they digest
their food. Most of the time, they swallow their prey
whole without chewing or tearing the flesh apart.
This means that owls naturally have a lot more bones,
feathers, and fur in their diet. After several meals of
whole animals, an owl collects a lot of indigestible
material in its gut. All this stuff is gathered in the
gizzard, a muscular pouch in the owl’s digestive
system.
The gizzard operates like a trash compactor, pressing
all the bones, fur, feathers, or other indigestible stuff
into a firm, ovalshaped ball. When the pellet gets
big enough, the owl spits it up and lets it drop to the
ground below.
Biologists who study owls depend on this kind of
information, and frequently analyze owl pellets as
part of their work in protecting wild owls.
The owl pellets you’ll be working with are totally
sanitary. They have been sterilized to kill any bacteria
or parasites that might have been present in the
pellets when they were fresh. Owls have powerful
stomach acids that usually kill all the bacteria in the
pellets. Sterilizing the pellets before packaging them
is an added precaution. The only problem you might
have is if you are allergic to dust. Owl pellets are
dusty, but you can get around this by spraying them
with a plant sprayer as you work on them, or by
wearing a dust mask.
Owls in the wild eat whatever is on the local menu.
In other words, owls living where there are lots of
mice will eat (you guessed it!) mice. They also eat
other things depending on what’s available, including
insects, frogs, mice, weasels, small birds, even larger
prey like porcupines. As you might expect, larger owls
like larger prey, and smaller owl species eat smaller
prey. The smallest owls, such as Canada’s Pygmy Owl
and Boreal Owl, depend on insects, small birds, frogs,
and mice. The Great Horned Owl, Canada’s most
common owl, eats a great variety of things including
ducks, porcupines, squirrels, grouse, along with its
staple food of mice.
The stuff in an owl pellet can tell you a lot about
what the owl has been eating. It can also tell you
something about the prey animal itself, because its
remains are nicely preserved in the pellet.
Get to Know Program • 201-2040 Springfield Road. • Kelowna, British Columbia • T: 250-980-3969 • E: [email protected] • gettoknow.ca
GRAB N’ GO ACTIVITY:
Dissecting Owl Pellets
PREPARATION:
Owl pellets: you can buy owl pellet dissection kits
from any of several science supply companies. See
the section “Sources and Resources” at the end of
this activity plan for places to get owl pellets. If this
activity is new for you, we recommend you dissect an
owl pellet of your own as part of your preparation.
For ideas on how to prepare your students so they get
the most out of this experience, see the section on
“prior knowledge” above.
SAFETY:
If any of your students have allergies to mice, animals,
or dust, you should provide them with dust masks to
wear, or use a plant sprayer to moisten their pellets as
they work to control airborne dust particles.
PROCEDURE:
The student worksheet contains complete
instructions on how to do this activity. Go over these
steps with them before allowing them to proceed.
TIPS AND ENRICHMENT:
• If you only have one pellet and / or would like to
do a dissection that the whole class can see, use
an overhead projector and screen. Your entire
class can watch while you demonstrate how
to break up the pellet and what can be found
inside. You can arrange the bones and other
remains on a piece of plastic transparency film.
• Dissecting microscopes can be used to help
find and identify smaller bones. If you have
dissecting microscopes, be sure your students
know how to use them.
SOURCES AND RESOURCES:
1. Boreal Northwest (the recent merger of Boreal
Laboratories and Northwest Scientific) has a
comprehensive list of owl pellet education
resources including supplies of owl pellets,
dissecting kits, posters, and much more. Go to
http://boreal.com
2. Skulls Unlimited, Oklahoma City, OK. Class kits
available. Go to http://www.skullsunlimited.com/
owl-pellet-sets.htm
3. Workman Publishing, New York: “Owl Puke” kit
includes an owl pellet, dissecting tools, sorting tray,
and a wonderfully written and illustrated book on
the topic of owls and owl pellets. See http://www.
workman.com
4. Jim Cornish of Gander, Newfoundland has
developed an excellent student activity on owl
pellets. You can download a pdf copy from http://
www.cdli.ca/CITE/pellet_activity.pdf
• Create a mouse “fossil” by arranging recovered
mouse bones on the surface of some wet
plaster of Paris. Allow the plaster to set, spray
the surface with cooking spray, and pour more
plaster over the bones. The spray allows the two
halves of the plaster imprint to be separated.
This will give you an artificial fossil that mimics
the challenges faced by palaeontologists who
extract delicate fossils from sedimentary rocks.
Get to Know Program • 201-2040 Springfield Road. • Kelowna, British Columbia • T: 250-980-3969 • E: [email protected] • gettoknow.ca
GRAB N’ GO ACTIVITY:
Dissecting Owl Pellets
MATERIALS:
To complete this activity, you will need:
• One owl pellet
• Sheet of newspaper
• Sorting tray (egg carton, plastic ice cube tray or
other container with small compartments)
• Fine tweezers or forceps
• Glue (regular white glue or hot melt glue gun)
• Sheet of stiff paper or thin cardboard
• An old toothbrush (marked so that no one uses
it by mistake to brush their teeth!)
• Magnifying glass (optional)
PROCEDURE
1. Find a clean place to work and lay out all the
materials as described in the list above. Be sure
you have good lighting.
of fir and dirt, a smaller one with small bones,
and a third with identifiable plant bits such as
seeds.
10. Your next task is to identify and sort the
bones. Use the chart below to help you
identify them. Place each kind of bone in its
own compartment in your sorting tray. Use
the bone identification chart to help you.
MOUSE BONE IDENTIFICATION CHART:
The bones and other material you got from the
pellet can tell you something about the owl’s eating
habits. Based on the “evidence”, answer the following
questions:
1. What animals did the owl eat (hint: don’t
assume the owl ate only mice)?
3. Unwrap the owl pellet over the newspaper.
2. Is there evidence of more than one animal in
the pellet? How many animals may have been
eaten by the owl to make this pellet?
4. Break the pellet in half, then into smaller
and smaller pieces. You can do this with your
fingers, or you can pick it apart with a tool like a
nail or needle.
3. Is there plant material in the pellet? How do
you think it got there?
5. As you break the pellet into smaller and smaller
pieces, you will notice small bones. Use the
tweezers (forceps in science-speak) to place
them in the sorting tray.
7. The bones may have fur tightly packed in and
around them. You’ll need the small brush to
remove it.
8. Work through every bit of material from the
owl pellet removing any tiny bones you find.
If you find seeds, spruce needles, or other
identifiable plant material, put this into it’s own
pile.
9. When you are done taking apart the pellet, you
should have three piles, the biggest with bits
4. Select some bones from your sorting tray and
use them to build a partial skeleton of one of
the owl’s prey.
5. Glue the bones onto the cardboard in the same
way they are arranged in the Mouse Bone
Identification Chart, and label them.
Submit your work to the Get to Know Contest
for a chance to win wild prizes & go to
gettoknow.ca
to find more free resources and activities
Additional Resources:
Find more Educational Resources at:
www.gettoknow.org/education/
Get to Know Program • 201-2040 Springfield Road. • Kelowna, British Columbia • T: 250-980-3969 • E: [email protected] • gettoknow.ca
GRAB N’ GO ACTIVITY:
Dissecting Owl Pellets
Skulls
Jaws
Shoulder
Blades
Front
Legs
Hips
Hind Legs
Assorted
Ribs
Assorted
Vertebrae
SOURCED AND ADAPTED FROM: http://www.vrml.k12.la.us/Upload/bonesortingchart.jpg
GRAB N’ GO ACTIVITY:
Dissecting Owl Pellets
MOUSE BONE CHART
Get to Know Program • 201-2040 Springfield Road. • Kelowna, British Columbia • T: 250-980-3969 • E: [email protected] • gettoknow.ca