Owl pellets contain the indigestible remains of owls' prey such as bones, fur and feathers, which owls regurgitate. By examining the contents of owl pellets, one can determine what animals the owl has eaten and the owl's role as a predator. Owl pellets also provide habitat for other small animals and insects, forming a mini ecosystem within the pellet.

1. beak keen eyesight regurgitate
bird of prey keen hearing silent
carnivore nocturnal special feathers
egg owl stealthy
hunter pellet talons

2. Fill in the blanks below with words from this box:
Nocturnal, falcons Prey eyesight Hawks hearing
insects Hunt
Mice Stealthy Birds camouflage
late swallow flap regurgitate feathers pellets
night
fish
Nocturnal Animals
Most owls are __________________ animals, which means they are mostly
active at ___________________. Because they are active in the dark, they
need keen ___________________ and ___________________.
Birds of Prey
Owls are birds of ___________________ like ___________________ and
___________________. That means they __________________ small animals such as
___________________, ___________________, and other ___________________.
Some owls even catch ___________________ in water. Often, an owl will
___________________ an animal whole. But since it can’t digest the bones, it will
___________________ them. These regurgitated bits of food are called
___________________.
Owl Feathers
Owls are ___________________ hunters. They have special
___________________ that help to keep
them quiet when they ___________________ their
wings. Owl feathers are usually brown and grey,
which helps to ___________________ them in the
forest. Because owls are so silent and hidden,
their prey doesn’t know the owls are coming until
it’s too ___________________.

3. Virtual Owl Pellet Dissection Worksheet
Glue and Draw the bones you find.
Length: ________________
Width: ________________
How many of the following
bones did you find?
Humerus: ________
Femur: ________
Lower Jaw: ________
Skull: ________
Vertebrae: ________
Shoulder Blade: ________
Ulna/Radius: ________
Ribs: ________
Pelvic Bones: ________
Tibia/Fibia: ________

4. How many animals did this owl eat?
What do the contents in this pellet tell you about the owl’s diet?
What habitat do you think this owl would be hunting in?
If your animal has... Then...
1. a) 3 or fewer teeth on each side of its upper jaw? go to 2.
b) At least 9 teeth on each side of its upper jaw? go to 3.
2. a) 2 biting teeth on its upper jaw? go to 4.
b) 4 biting teeth on its upper jaw? the skull is from a rabbit.
3. a) A skull length of 23 mm or less and brown teeth? the skull is from a shrew.
b) A skull length of more than 23 mm and 44 teeth? the skull is from a mole.
4. a) The roof of its mouth extending past the last molar? go to 5.
b) The roof of its mouth not extending past the last molar? go to 6.
5. a) A skull length of 22 mm or less? the skull is from a mouse.
b) A skull length of more than 22 mm? the skull is from a rat.
6. a) Flat molars (back teeth)? the skull is from a meadow vole.
b) Rounded molars (back teeth)? the skull is from a deer mouse.

5. SPOTTED BOREAL ELF SAW-WHET
PYGMY HAWK GREAT HORNED SNOWY
SCREECH LONG-EARED SHORT-EARED GREAT GRAY
FLAMMULATED WHISKERED BARRED BURROWING
A H H R S D E T A L U M M A L F A
N D L D O C A G N I W O R R U B E
Y D E O W O R T R R D G D G A R W
S A E R N L D E R A E T R O H S R
G P R R E G A W E S A W W H E T N
A D O G R K E E A C O E B U A S U
B T K T T A S A R M H L B A N R S
I N T W T A B I R O R O G O G L E
G L A F A E E A H E B L W E A T W
D R L F G H D R L W D Y D A G R E
G E E O N T P Y G M Y E R L S E N
E G R E A T H O R N E D F E L O S
R E E E R R Y D S W E O R A N R T
Owls
1
As night falls, this bird slowly emerges from its daytime
sleep. It rests on a tree branch in the dark and uses its acute
hearing to pick up sounds made by prey. It occasionally turns its
head three-quarters of the way around to look for its next meal.
Once a victim is located, it launches a surprise attack by

6. approaching the prey in silence. This skillful hunter is an owl!
2
There are over 200 different types of owls. They can be found in all places except for the
region of Antarctica. Most owls are active at night. However, there are a few species of them -
such as snowy owls living in the Arctic - that hunt in broad daylight. Owls usually live alone or
in pairs. During the mating season, however, owls may gather in groups. A group of owls is
called a parliament. Owls are the so-called "birds of prey" because they eat living animals like
lizards, birds, fish, or insects. Birds of prey share several common features that make them great
predators - they have hooked beaks, sharp claws, and keen eyesight. Eagles, hawks, and falcons
are other examples of birds of prey.
3
Owls have large, round heads with big, forward-facing eyes. Like our eyes, theirs can see
objects in three dimensions (height, width, and depth), and can judge distance. Unlike our eyes,
theirs cannot roll or move in their sockets. To make up for this disadvantage, owls have 14
vertebrae (bones) in their necks allowing them to turn their heads 270 degrees and almost upside-
down!
4
Owls rely as heavily on their hearing as on their eyesight to catch prey in a pitch-dark
environment. Covered by feathers, the ears of owls are behind their eyes. Eagle owls, together
with several other species of owls, have ear tufts on their heads. These ear tufts are actually just
feathers sticking out from both sides of their heads, and they have nothing to do with hearing!
Interestingly, many owls have asymmetrical ear openings - one ear is slightly higher than the
other. This special feature enables them to tell if a sound comes from left or right, from up or
down. For example, barn owls' left ears are higher than their right ones. If a sound is from the
left side of a barn owl, its left ear hears the sound before its right ear. Similarly, if a sound is
from below, it reaches a barn owl's right ear first, because the right ear is slightly lower than the
left one. As a barn owl turns its head around, its brain processes all the information and creates a
"mental image" of the space to locate the sound source.
5
Once owls pinpoint the location of their prey, they fly straight toward it. Even if their prey
moves around, owls are able to change their directions in mid-air. When owls fly, they do so in
silence. The feathers near the tips of their wings have comb-like fringes. These fringes
effectively muffle the sound of the air rushing over the wing surface so owls can fly quietly. As
owls come closer to their victim, they bring their feet forward and spread their claws wide - this
is their ready-to-strike posture!
6
Owls swallow their prey whole because they, like other birds, cannot chew. To get rid of the
indigestible parts of their prey (furs, teeth, bones, or feathers), owls first compress these
indigestible parts into small balls, called pellets. Pellets may stay inside owls' bodies for up to 10
hours before being regurgitated (thrown up). Because pellets take space, owls cannot hunt and
swallow new prey unless they regurgitate the stored pellets from their stomachs first. Therefore,
regurgitation often means that owls are ready to eat again!

7. Name _____________________________ Date ___________________
Owls

8. 1. What is a group of owls called? 2. Which of the following statements about
A school owls is true?
A parliament Owls can see objects in three
A bunch dimensions but cannot judge distance.
A flock Owls have seven vertebrae (bones) in
their necks.
A barn owl's right ear hears the sound
first if it comes from the right side.
Owls use their asymmetrical ear tufts
to determine the location of sound source.
3. Which of the following statements about 4. Owls and eagles have several things in
owls is true? common EXCEPT for which one below?
Owls rely on their noses to detect the Both owls and eagles are birds of
smell of their prey. prey.
If their prey moves around, owls must Both owls and eagles hunt during the
stop and figure out again where the prey is. day.
Owls can be found in all parts of the Both owls and eagles have sharp
world. claws.
Owls have forward-facing eyes. Their Both owls and eagles have hooked
eyes do not move in their sockets. beaks.
5. Ear tufts are feathers. 6. Other than acute hearing and keen eyesight,
False what is the third factor that makes owls
True great predators?
Their ability to regurgitate pellets
from their stomachs
Their ability to digest animals' bones
and feathers
Their ability to chew food
Their ability to fly in silence
7. A pellet is a compressed ball of indigestible 8. Why do owls throw up?
parts of owls' victims. Owls throw up if they are sick.
False Owls throw up if they do not like the
True taste of their prey.
Owls throw up if they have
stomachaches.
Owls throw up to make rooms in their
stomachs for the new prey.

9. Owls - Answer Key
1 A parliament
2 A barn owl's right ear hears the sound first if it comes from the right side.
3 Owls have forward-facing eyes. Their eyes do not move in their sockets.
4 Both owls and eagles hunt during the day.
5 True
6 Their ability to fly in silence
7 True
8 Owls throw up to make rooms in their stomachs for the new prey.

10. Owl Pellets
Background
Owl pellets are masses of bone, teeth, hair, feathers and exoskeletons of various animals preyed upon by raptors, or
birds of prey. Pellets are produced and regurgitated not only by owls, but by hawks, eagles and other raptors that
swallow their prey whole of in small pieces. Owls feed fearly in the evening and regurgitate a single pellet
approximately 20 hours after eating. Unlike snakes, the protein enzymes and strong acids which occur in the
digestive tract of raptors do not digest the entire meal. The relatively weak stomach muscles of the bird form the
undigested fur, bones, feather etc. into wet slimy pellets. In this process even the most fragile bones are usually
preserved unbroken.
The owl pellets that you will be examining in this lab have been collected and fumigated from common barn owls.
Owl pellets themselves are ecosystems, providing food and shelter for communities which may include clothes
moths, carpet beetles and fungi. Clothes moth larvae are frequently abundant in pellets, feeding on fur and feathers.
The black spheres about the size of periods (.) that are found in the pellets are the droppings of the caterpillars. The
larvae metamorphose near the surface of a pellet in cocoons made of fur.
Objective.
We will examine the bones found in the pellet to identify what animals the owl ate. The
most common prey for barn owls include smaller birds, mice, moles, voles, shrews, rats and
insects. The easiest part of a skeleton to identify is the skull.
Materials
• Owl pellets (http://www.pelletlab.com/
• Dissecting Needle/toothpicks & tweezers
• Large white glue
• Aluminum foil
• 5" X 8" index card, no lines (Construction paper)
• Fine black felt tip marker
• Owl Research Notes student sheet
• Paper
• Bone Chart (Owl_Pellet_Bone_Chart_grid.pdf)
Procedure
1. Measure the length and width of your owl pellets.
Length of your owl pellet_______
Width of your owl pellet_______
2. Carefully examine the exterior of the pellet. Do you see any signs of fur? _____ any signs of feathers?_
3. Carefully use a toothpick to break apart the owl pellet and observe what is within. Use a toothpick to expose all
bones for identification. Use the bone diagram to help you identify your bones and complete the chart.
4. Organize the bones into groups and label them, use the attached chart to help you identify bones. Construction
paper will serve as a mounting surface. Grade will be based on neatness, labeling and organization.

11. Bones Found
Bone Number
Type
Skull
Jaw
Scapula
Forelimb
Hindlimb
Pelvic Bone
Rib
Vertebrae
Your job is to put these bones back into a complete skeleton. To do this you will need to identify
different bones from the bone chart at the bottom of this page. If you select the correct bone, it will
be placed on the gray workspace above. If you select the wrong bone you will be given a little help.
Let's start with an easy one.

12. Analysis
1. What do we know about the digestive system of an owl based upon the pellets?
2. Owl pellets not only can give us information about the diet of the owl, owl pellets also provide a habitat for other
animals, in fact an owl pellet is a little ecosystem all on its own. Why kind of animals are found in the owl pellet
ecosystem (Hint: read the background at the beginning)
3. Other types of birds form pellets. What would you expect to find in the pellet of a seagull?
4. Owls, hawks, and eagles are types of raptors, animals which have hooked beaks and sharp claws, and are
therefore adapted for seizing prey animals. Hawks and eagles differ from owls in that they eat their prey animals by
tearing them into small pieces, picking out the flesh and avoiding most of the fur and bones. They also have strong
stomachs which can digest most of the bone material which they might eat. The relatively small amount of
indigestible bone and fur that remain will be compacted by their stomach muscles into a pellet similar to the owl’s.
Do you think an eagle pellet would be as useful for dissecting as an owl's? Why or why not?
5. Construct a diagram of a food web (of at least 5 animals) with an owl at the uppermost trophic level. Use an arrow
to show which organism in the consumer or predator.
6. Conclusion: What did you learn from this lab? Are owls harmful or helpful to human beings?
How? How can you compare owls to other birds?