Owl Pellet Lab Student Data Sheet (Page 2 of 4) in pdf

Owl Pellet Lab Student Data Sheet Page 2

5. Count the number of each type of bone and record the information on your bones data

table.

6. Reassemble the skeletons by laying them out on a piece of paper. Glue or tape the

skeletons on the paper. Label the bones you have identified. You will only get credit if it looks

like an animal skeleton. If it looks like a bunch of bones taped on a piece of paper, you won’t

get the credit.

Using a Dichotomous Key to identify Prey

7. Use the supplemental handout with the dichotomous key to identify the skulls in your pellet

number found in your sample

and fill out the

column on your owl prey chart.

Barn Owl Diet

8. As you have seen from the dichotomous key, there are many genera of prey that occur in

the northwestern region of the United States. Any other animal remains you find in your pellet

from a bird, bat or insect. List them as “other prey” on the owl prey chart.

total number

9. Your teacher will gather class totals for each type of prey. Record these in the

of samples

column on your chart. To calculate the total biomass, multiply the numbers in the

total number

prey biomass.

column by the numbers listed for

cumulative biomass total

10. Add all of the totals together to get a

for all of the owls your class

sampled. Record this value on your chart.

11. Now it is possible to get a good idea of what each prey species contributes to the diet of

the northwestern barn-owl population that contributed to the owl pellets. To calculate the

total

percent each species contributed to the cumulative total biomass, you can divide the each

biomass

cumulative total biomass

value by the

. Write your results in the % Biomass column.

Your total should add up to 100%.

Owl Pellet Lab Student Data Sheet Page 2