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ParkWise
> Teachers >
Nature > To
Hatch or Not to Hatch
> Unit Outline
Activity
4:
Productivity and Prey
Students
graph real prey species and eagle reproduction data to see how prey
abundance affects the reproduction in eagles.
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Unit:
To Hatch or Not
to Hatch?
Guiding Questions: How
can scientists describe the reproductive rate of golden eagles?
How do scientists study the relationship between the abundance
of hare and ptarmigan and the reproductive rate of golden
eagles in Denali National Park?
Critical Content: The
correlation of prey abundance and reproductive rates. How
predator reproduction correlates with prey population cycles.
Grades: 5-8
Duration:
45 - 60 minutes
Group size: students
work as individuals
Setting: classroom
Materials: graph
paper, pencils, rulers, Denali
hare and ptarmigan abundance data (pdf), and
reproductive rates data for golden eagles. Either use Reproduction
Data Worksheet for Denali Golden Eagles that students
completed in Activity
3: Productivity, or use Summary
data, tabular (pdf)
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Before
you begin:
- Print and copy the
data sets for hare and ptarmigan and the reproductive data sets
for golden eagles.
- Print out the graphs
as well to check student results.
Procedures:
- Have students write a hypothesis of how they would expect the
population of prey species to affect the productivity of golden
eagles.
- Students should create two graphs with the year on the x-axis
and numbers of individuals sited on the y-axis and graph the data
first for the average number of hares observed and then for the
average number of ptarmigan observed.
- Then students should graph the total number of golden eagle
nestlings observed. Again the year should go on the x-axis and
the number of nestlings on the y-axis.
- Compare all three graphs.
Adaptations:
- For older students:
have students graph the range of descriptions of reproduction:
total number of fledglings, occupancy rate, laying rate, success
rate, mean brood size and productivity.
- For younger students:
assign to each student only one graph: average number of hares
observed, average number of ptarmigan observed, or one of the
reproduction descriptions (see above). Students should still work
individually. But compare their results as a class.
Discussion
Questions:
- Does eagle reproduction
correlate with prey abundance?
- Which years had the
highest golden eagle reproductive rates? Which years had the highest
population of ptarmigan and hare?
- Which years had the
lowest?
- Which reproductive
calculations varied the most with prey number?
- Which reproductive
calculations varied the least with prey number?
- PreK-2: Discuss qualitative change - which years
did the prey populations rise and fall, which years did the eagle
productivity rise and fall? Discuss quantitative change
- how much did the population and productivity change?
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