Park BIO BI111 – The Food Web

| March 13, 2016

Question

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The Food Web

The Food Web
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Version The Food Web

Lab Report Assistant
This document is not meant to be a substitute for a formal laboratory report. The Lab Report
Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data
tables that should be addressed in a formal lab report. The intent is to facilitate students’
writing of lab reports by providing this information in an editable file which can be sent to an
instructor.

Data Table 1: Record of bones in owl pellet.
Mole

Rodent

Shrew

0

0

1

0

0

2

0

1

1

2

1

2

4

3

5

1

2

3

4

6

6

Skull

Lower jaw

Scapula

Forelimb

Hindlimb

Pelvis

Rib

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Experim

The Food Web

Questions
A. Assuming an owl produces one to three pellets per day, what is your estimate of the annual

food consumption of one owl based upon the results of dissecting this pellet? For example, if
you find three mice and one mole in one owl pellet, that means four animals were
consumed in one day if one pellet is regurgitated. If three pellets are regurgitated and there
is an average of four animals/pellet, that is approximately 12 animals consumed in one day.
Use this range to estimate the number of animals consumed in one year.
Upon my results of dissecting this pellet my estimated food consumption amount per year is
approximately 3,285 animals that the owls consume per year assuming that the owl
produces three pellets per day. During my finding it was very interesting that I only located
one skull of a shrew and a consistent amount of scapula, limbs, pelvis and ribs of each
animal. Based on my readings I understand that the owl could have regurgitated the missing
parts before or after, also the bones could have been more digested making it harder to fully
identify all parts. Therefore, based on my calculations and findings, I estimated that the owl
consumes approximately 9 animals per day, regurgitating 3 animal’s remains a day, giving us
the average of 3,285 per year.

B. How accurately do you think the content of owl pellets reflects the proportion and

abundance of the animals in the area where this pellet was collected?

I believe that the owl pellets cannot reflect 100% accuracy of the proportion and/or
abundance of the animals in the area where the pellet was collected. This is a random
sample, factors to consider are when the owl catches they’re prey and what’s actually
available in the area. It is difficult to arrive a conclusion based on one pallet, but if I had to
choose I would say that shrews and rodents are in abundance based on my findings from
dissecting the pallet.

C. Draw a diagram of a food web using information derived from the animals dissected in the
pellet. Assume that the owl is positioned at the highest trophic (feeding) level. Make your
diagram as comprehensive as possible. Use dotted lines to indicate uncertain relationships.

D. Why might seeds and other plant material be found in owl pellets?

E. Describe how you would build a self-contained, aquatic micro-ecosystem. The system would
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The Food Web

be sealed off from the outside world, except for light. What are the organisms that would be
necessary and why? You must have at least two trophic levels represented, but more are
probably necessary. Diagram the food web that would exist in your microcosm.

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