·
You will need a camera for this lab.
·
Main heading for your post: Owl
Pellet and Energy Pyramid Lab
·
Subheadings: Part 1 Owl Pellet
Dissection, Part 2 Ecological Pyramids
·
See what to submit under each part.
You will only work with one pyramid in Part 2.
Objectives
1.
Demonstrate an
understanding of the nature of science and the scientific process.
2.
Classify animals according
to type of skeletal structure.
3.
Identify bones that compose
the skeletal system.
4.
Trace the flow of energy
through the trophic levels and energy pyramids.
5.
Explain how organisms
interact within an ecosystem and how owls affect an ecological community.
6.
Demonstrate analysis of
data to produce visual results and written explanations.
7.
Perform calculations to
determine patterns.
8.
Demonstrate collaborative
skills.
Introduction
Owl pellets
are the undigested remains of prey ingested by an owl. The owl swallows its
prey whole, and during the process of digestion, the soft parts of the prey are
dissolved and passed on to the intestine for absorption. The hard,
non-digestible parts-bones, teeth, fur, feathers, and chitonous remains of
insects are compressed in the gizzard and passed on to the proventriculus, the first
chamber of the owl’s stomach, where the pellet remains until it is
expelled. These pellets are not eliminated as feces, but are regurgitated
through the mouth.
The Common
Barn Owl feeds in early morning and early evening and will usually produce one
to two pellets per day. Glossy black
when fresh, the pellet remains smooth and dark in color when dry. Your pellet
has been fumigated to eliminate the presence of any insects and then individually
wrapped for preservation. Unless otherwise stated, the pellets in this lab are
from the family Tytonidae and more specifically, the Common Barn Owl, Tyto
alba.
Safety
1.
Be careful
with sharp tools and bones.
2.
Wash hands after
activity.
Materials
Owl pellet
Camera
Dissecting surface
Scale
Bone sorting charts
Other small tools, as supplied
Glue
Sheet of plain paper or cardboard
for mounting bones
Part 1 Owl
Pellet Dissection
·
What
to submit for this part:
o
Table
1 (1 points)
o
Photo
of chart with sorted bones (2 points)
o
Photo
of reconstructed skeleton (2 points)
o
Table
2 (1 points)
o
Graph
of species numbers (2 points)
o
Comments
about other species found
Procedure
1. Remove the
pellet from the aluminum foil.
2. Measure the
length and width of the pellet and record these measurements in Table 1.
Table 1. Owl
Pellet Measurements
|
|
Length
|
1 5/8”
 |
Width
|
1”
 |
3. Place the
pellet on the dissecting surface. Carefully separate the bones from fur or
feathers onto another part of your surface using your fingers and available
tools.
4. Carefully clean
the bones by picking or scraping off debris and sort them according to type—skulls,
jaws, vertebrae, etc.
5. When you are
sure that all bones have been separated, dispose of the other materials in the
trash.
6. Identify the
animals found in your pellet by matching the bones in your pellet with those in
the Bone Sorting Chart.
7. Place each bone
beside the matching bone on the Bone
Sorting Chart.. You may have many of each
type of bone sorted and glued or just a few.
8. Take a photo of
your chart with the sorted bones.
9. Reconstruct a
partly complete skeleton of one prey animal. Glue the parts on a sheet of
paper and take a photo.
I could not figure out how to do the ribs or the pelvis with what I had
I could not figure out how to do the ribs or the pelvis with what I had
10. Record the
types and numbers of animals in Table 2.
Table 2. Kinds and Number of
Animals Found in Owl Pellets
|
|||||
No. Voles
|
No. Shrews
|
No. Birds
|
No. Moles
|
No. Rats
|
|
Your Data
|
1
|
||||
11. Make note of
any other species you can identify.
I can only make out one type of animal
from this owl. The bones collected were that of a rodent, but with the sharp upper
and lower front teeth I can only assume a rat.
12. Construct a bar
graph of the data in Table 2, using the grid below or another source.
Part 2 Ecological
Pyramids
The amount
of energy or matter in an ecosystem can be illustrated by a drawing called an
ecological pyramid. In this activity you will construct three types of
ecological pyramids, a number pyramid, a biomass pyramid, and an energy
pyramid.
Each pyramid
you construct will consist of four trophic levels. The top of each will relate
to your owl, the only tertiary consumer (3o). The next level
down will relate to the owl’s prey, the secondary consumers (2o).
For the purposes of this activity, assume the prey found in the owl pellets are
secondary consumers. The next trophic level down will relate to the organisms
eaten by the owl’s prey, the primary consumers, (1o). The
base of each pyramid will relate to the organisms eaten by the primary
consumers, the producers. Use the
information obtained from your owl pellet dissection to construct the
ecological pyramids below.
A. Energy Pyramid for
a Trophic Level.
·
Only
students with last names starting with Q through Z perform this part.
·
What
to submit for this part:
o
Drawing
or depiction of your energy pyramid. You may not copy and paste someone
else’s pyramid. (5 points)
o
Calculations
for number 2 and 3. (2 points)
o
Answer
questions 1-5 (5 points)
An energy pyramid is an ecological pyramid that indicates
the amount of energy in
each feeding level. According to the terms of thermodynamics, only about 10% of
the energy available within one trophic level is transferred to organisms at
the next trophic level.
1.
Assume that the producers
in this pyramid (plants) contain a total of 500,000 Calories of food energy. Draw
an energy pyramid and label the base with this value.
2.
Calculate the amount of
energy for the 1˚ consumers by multiplying the food energy of the producers by
0.10. Write this value in your pyramid.
3.
Complete your energy pyramid
by calculating and labeling the energies for the top two trophic levels.
Assuming that the barn owl regurgitates one pellet per day, how many prey items
would the owl that produced your pellet consume per year?
Based on the owl pellet I had this owl is trying to watch her
figure as there is only 1 mammal. If an owl is eating 2 times a night that’s only
370 rodents per year. Which is also the amount of pellets this particular owl produces.
Answer these questions.
1.
Where does the pellet remain until it is expelled?
The pellets remain inside the owls stomach until the owl is has digested
all the nutrients it needs.
2.
List 6 other birds that are known to regurgitate pellets.
Hawks, Eagles, Falcons, Owls, Kestrels, American Goldfinch, and swallows.
3. Placing the owl
at the highest trophic level, create a food web using the following items: vole, deer mouse, mole, house mouse, weasel,
shrew, snake, starling, frog, salamander, spider, grubs, earthworms,
centipedes, crane fly, seeds, plants, roots.
4. Why does the
number of organisms decrease as you move up the pyramid
level?
Because
there are fewer prey then there are predator. The predators are doing their job
to maintain balance and the pray is doing their job to maintain them.
5. We know that
about 50% of the energy in an organism is not digested by the consumer and is
simply passed through as waste or feces. Is the energy stored in the feces lost
to the ecosystem? Why or why not? No the
energy stored in the feces is not lost. The energy, one way or another, gets consumed
or is biodegradable to fertilize the plants around it. The insects that feed on
the fecal matter also have access to it, then in turn is eaten by a bigger bug or
a bat or another insect eating creature and so on.
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