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Nature > To
Hatch or Not to Hatch
> Unit Outline
To
Hatch or Not to Hatch?
Activity 2:
Connections
Students
try to identify how changes in the ecosystem affect species populations.
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Unit:
To Hatch or Not
to Hatch?
Guiding Question: What
affects the number of chicks a pair of golden eagles in Denali
National Park and Preserve will have? Which of these factors
is the most important?
Critical Content:
Prey species abundance
varies cyclically over years. Habitat quality and quantity
are necessary to support prey species.
Grades: 3-8
Duration: 45 -
60 minutes
Group size: 15
- 30 students
Setting: classroom
Materials: Index
cards, markers, tape or string, Denali
Ecosystem - Who Eats What?
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Before
you begin:
- Have students brainstorm
and discuss the guiding questions. Review Golden
Eagles in Denali. Students should conclude that abundance
of prey and safe nesting sites are important factors.
Procedures:
- Be sure that every student should have a card with a species
written on it.
- The card should be taped to the front of their shirt or hung
with a string around their neck, so that it is visible.
- To start, have all the students seated and have them stand
if they are a producer, then have the predators stand, then have
the prey species stand. You may need to define producer, predator
and prey.
- Once the students understand their role then they should form
a circle with all the students standing and have desks or chairs
behind each student.
- Use the list provided to call out different events that happen.
- The students should react if their species is affected. If
the population remains steady they stand. If they die off then
they should sit on the floor. If the population declines then
they should sit on a chair and if the population increases then
they should stand on a chair.
- It should be apparent that many species are affected by a single
event. You can start again after each event with all the students
standing or you can continue from where you left off and have
a series of events take place.
Discussion questions:
- What types of events cause populations to shrink?
- What types of events cause populations to grow?
- How does reproduction affect population size?
- What is extinction? Why might a species go extinct?
- What if animals did not reproduce? [they would eventually go
extinct]
Suggested events: fire,
cold winter, over-hunting of a particular species, virus that effects
a particular species, a decline of one category of species, a population
boom of one category of species, drought.
Extensions:
To follow up students can look at the graphs for snowshoe hare and
ptarmigan populations and discuss the cyclical nature. Write possible
explanations for the cyclical nature of this prey species abundance.
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