Owl Pellet Lab
Name
Hour
OBJECTIVES

Use tooth structure of prey animals to determine potential feeding relationships in a community

Determine the relative number of organisms at different trophic levels in a barnyard community

Construct a food web to demonstrate the feeding relationships in a barnyard community
PROCEDURE
1. Carefully separate the owl pellet into a few large sections
2. Remove fur to expose and clean any large bones
3. Examine the remaining fur to find and separate any other remains (small bones, insect parts, feathers)
4. Identify the types of organisms found in your pellet to determine their probable trophic level.
5. Determine the total number of each type of prey animal in your pellet
DATA
Type of Prey:
Number of Prey
Class Data
Total number of pellets examined =
Small herbivores
Larger herbivores
Small omnivores
Larger omnivores
Small carnivores
Larger carnivores
CALCULATIONS
Determine the average number of prey per pellet (using class data)
If an owl produces one pellet per day, how many prey will one owl consume in one year?
CONCLUSION
1.
Explain how the trophic level of prey animals can be determined by examining their bones.
2.
Which trophic level(Io, IIo, IIIo) is most common for the barn owl? How do you know?
3.
What evidence suggests that the barn owl may occupy more than one trophic level?
4.
If the bodies of voles (the most common small herbivores found in owl pellets) contain an average of 1 microgram
of some toxic substance, how much of that toxic substance would be taken into the body of a barn owl over one
year?
5.
Use your observations in this lab activity to explain the concept of an ecological pyramid. Draw a pyramid for this
community using examples from the lab.
6.
Construct a food web for this community. Include the following organisms:
grain; grass; deer; voles; herbivorous insects; carnivorous insects; worms; shrews; coyotes; rabbits; barn owls.