Owl Pellet Investigation
By: Paige Gottlieb Period 7 Code: 12
Introduction
The purpose of this investigation was to find out what the Barn owls eat. To find out what
the owls ate, the class had to dissect an owl pellet. Inside of the pellet we found feathers, bones,
and fur. When owls eat their prey, they swallow the animal whole, then the owl forms a pellet of
the bones, fur, and what ever else the owl can not swallow. Then the owl regurgitates the pellet.
Barn owls like every owl are raptors. This means the owls have special adaptations. The
owls have sharp talons to rip the flesh of their prey. Owls are nocturnal, they have a keen sense of
sight in the dark to spot their prey. They can turn their head 270 degrees the way around, since the
owls eye sockets do not move. The owls also have a vivid sense of hearing, which also helps for
the owls to find their prey. The Barn Owl is a raptor and hunts very effectively, because of the
owls adaptations. This year we had 260 voles, the voles were the most popular animal. Do
Brookside’s previous years compare to this?
Procedure
1. First we measured, weighed, and observed our owl pellets.
2. Then we began dissecting the owl pellets
3. While still in the process of dissecting the pellet, we counted and compared our bones to a
dichotomous chart.
4. After finishing dissecting the owl pellet, we began to glue the bones on a diagram of the animal
that we had
This is a Vole
Data Tables
Animal
Vole
Pocket
Gopher
Mouse
Shrew
Rat
Bird
Mole
Total
# found
53
4
7
0
0
0
0
64
Percent
83%
6%
11%
0%
0%
0%
0%
100%
Prey
animals
per pellet
1
2
3
4
5
6
7
>8
Total # of
pellets in
class
Total
#prey
animals in
class
Number
of pellets
2
4
8
7
2
0
0
0
23
64
Percent
9%
17%
35%
30%
7%
0%
0%
0%
100%
100%
Animal
Vole
Pocket
Gopher
Mouse
Shrew
Rat
Bird
Mole
Total
# found
260
27
37
5
0
3
0
332
Percent
78%
8%
11%
2%
0%
1%
0%
100%
Prey
Animals
per pellet
1
2
3
4
5
6
7
>8
Total #
prey
animals in
grade
Total #
of
pellets
# of
pellets
8
30
32
20
11
4
0
1
106
331
Percent
7%
28%
30%
18%
10%
3%
0%
1%
100%
100%
Average number of
prey animals per
pellet
Type of prey animal
contained by most
pellets
Number of prey
animals contained by
most pellets
Least to greatest
number of prey
animals in pellet
3
Voles
3
1-8
Comparative Question
This year we had 260 voles, the voles were the
most popular animal. Do Brookside’s previous years
compare to this?
My prediction is that previous years data will
have voles as their most common prey animal.
Bar Graphs
Comparative question data
Years
20092010
20112012
20122013
20132014
Voles
202
306
256
283
Mouse
46
7
26
29
Pocket Gopher
0
4
21
29
Shrew
7
15
44
24
Unknown
Rodent
0
0
1
0
Bird
4
6
1
1
Mole
0
2
13
0
Rat
3
2
1
0
Discussion
1. Scientists use owl pellets to study the owls diet and habitat. The scientists dissect the owl pellets to find all of the bones. Then the
scientists identify what prey animal(s) using a dichotomous key. Then the scientist identify where the owls habitat is.
2.In my owl pellet I found 4 voles! I know this because When I was dissecting my owl pellet I had found 4 skulls (3 of them were
broken.) I found 14 mandibles and 3 fibulas.
3.The class average for the number of prey animals per pellet was 3 animals. In my pellet I also found 3 animals. About 35% of the
grade had 3 animals in their pellet.
4. Based on our data there would be way more prey animals then owls. If their were more owls in the food chain their would not be
enough prey for all the owls to eat. The owls only get 10% of the energy so they must eat lots of the prey for more energy.
5.If a barn animal produced two pellets a day, it would probably consume about 42 pellets per week. I say 42 pellets because the
majority of the grade found about 3 animals in their pellet. You must multiply three by two because the owl produces two per day.
Therefore about 180 animals per month, and about 2,190 per year!!
6.The most common prey species in the grade was the voles. The grade found about 260 voles. 78% of the grade found the voles. From
the data I can infer that the most common owls prey in is probably the voles
7.Some farmers around the world shoot the barn owls in fear that the barn owls will eat their chickens. The farmers are wrong for doing
that because the owls don't eat chickens. They hunt for animals including; voles, mice, shrew, pocket gophers, birds, and moles. The owl
won't eat their chickens.
Conclusion
The purpose of this investigation was to determine what the Barn owls ate. In Addition I wanted to find out if previous brookside
school years had voles as their most common prey animal. My prediction is that previous years data will have voles as their most
common prey animal for the owls. My prediction was successful for example in 2011-2012 they had about 306 voles and the voles
were their most common rodent. In this investigation there could have been many experimental errors. Some of the experimental
errors could be, some students may have counted the amount of animals wrong, or when we put the rodents bones on a presentation
sheet people may have put the bones in the wrong spot. Some improvements the whole class could make would be to work more
cooperatively, we could all finish the project faster. This lab helped me and my class find out what the Barn owls ate.