# Lesson 3: The Deer Population Cycle

Keywords: white tailed deer, population dynamics, habitat

Prepared by: David Jackson, Extension Educator

Total Time Required for Lesson: 60 minutes, classroom and activity time

Setting: Classroom and large open indoor or outdoor area

Topics: population dynamics, wildlife habitat

Goals for the Lesson

Upon Completion of this lesson students will be able to:

• Identify 3 of the 4 essential components of wildlife habitat.

• Describe 4 factors that influence wildlife populations.

• Discuss the reasons why deer populations fluctuate over time.

• Name the most limiting factor to Pennsylvania’s deer population.

• Graph deer populations on a seasonal cycle.

Materials Needed

• Graph paper and pencil

• 1.6.8.A Speaking and Listening – Listen to others. (PA State Standard Reading, Writing, Speaking, and Listening)

• 1.6.8.C Speaking and Listening – Speak using skills appropriate to formal speech situations. (PA State Standard Reading, Writing, Speaking, and Listening)

• 2.5.8.B Mathematical Problem Solving and Communication – Verify and interpret results using precise mathematical language, notation and representations, including numerical tables and equations, simple algebraic equations and formulas, charts, graphs and diagrams. (PA State Standard Mathematics)

• 4.2.7.B Renewable and Nonrenewable Resources – Examine the renewability of resources. (PA State Standard Environment and Ecology)

• 4.6.7.A Ecosystems and their Interactions – Explain the flows of energy and matter from organism to organism within an ecosystem.  (PA State Standard Environment and Ecology)

• 4.6.7.C Threatened Endangered and Extinct Species – Explain natural or human actions in relation to the loss of species.  (PA State Standard Environment and Ecology)

Methods: Lecture, Simulation, and Inquiry

Doing the Activity

Background:

• White-tailed deer populations naturally rise and fall at different times of the year.  Deer populations increase through births or when new animals move into the area (immigration).  Deer populations decrease through deaths or when animals leave the area or disperse (emigration).  Population change = (birth + immigration) – (death + emigration).

• Deer, and most other wildlife populations, show a regular pattern of increase after the breeding season and decline following hunting season and winter mortality.  The numbers of deer in a population varies over the course of a year.

• Late spring/early summer, with fawns being born represents the time of highest deer population.  Summer, predation on fawns reduces the deer population slightly.  Fall, hunters harvest surplus animals and reduce population level.  Mid-late winter represents the lowest population level due to some deer dying of starvation, predation, and disease.

• Many factors influence the ability of deer populations to successfully reproduce and maintain a constant population over time.  Some of these include: disease, predator/prey relationships, habitat destruction and degradation, food availability, hunting pressure, and weather conditions.  Deer populations are not static; they continuously change in response to many factors.

• Limiting factors prevent deer populations from reproducing in greater numbers than their habitat can support.  When limiting factors are in excess it may lead to a reduction in population levels.

• For deer to survive they need food, water, shelter/cover, and space to move about and find their daily requirements.  These are the essential components of habitat.  Without them, deer will not be successful at surviving and reproducing.

• Deer are herbivores, their food is composed of plants.  Deer receive most of the water they need from the plants they eat.  Shelter and cover are necessary for a deer to survive for a number of reasons; hiding young fawns from predators, protection from severe weather, and escape from hunters.  Each deer must be able to find all the food, water, and shelter/cover it needs within the area it travels.  This area is referred to as its home range.

Seasonal Population Cycles

1. In this activity, graphical representations of white-tailed deer population are studied within a given year by looking at seasonal fluctuations in populations and the factors that influence those changes.  Students will illustrate how deer populations change over the course of a year.

2. Begin the activity by asking students: What is a wildlife population?  It is the number of individuals of a given species (in this case deer) found in an area.  What might cause deer populations to increase or decrease in a given area?  What kinds of things might cause seasonal fluctuations in deer populations?  Explain to students that deer, and most wildlife, populations show a pattern of increasing with births during the spring and declining throughout the remainder of the year until they are at a low in late winter.

3. Have students work individually and prepare a graph representing the seasonal deer population cycle for two years.  Along the Y axis represent the population level (high, medium, or low).  Along the X axis label the four seasons (spring, summer, fall, winter).

4. Have students discuss the results of their graphs.  Discussion questions:  Why did they place the population levels where they did for each particular season?  What factors influenced the seasonal deer population?  What do deer need to survive?  What are some of the limiting factors that affect their survival?  Are deer populations static or do they tend to fluctuate?  Are deer populations ever really in balance with their habitat?  Does hunting play a role in keeping deer populations from exceeding what the habitat can support?

Conclusion & Assessment (Evaluation)

• Exhibit and Observation
Evaluate students based upon their participation and quality in preparing and discussing the seasonal population cycle graphs.  Assessment will be based on student’s ability to name a factor that may have caused the deer population to increase or decrease.

References:

• Penn State College of Agricultural Sciences, Cooperative Extension.  4-H Wildlife Project - Intermediate Unit Book 1.  The Wildlife Ecologist.  Chapters 2 & 3