Lesson 5: Estimating Deer Populations and Habitat Impact

Keywords: white-tailed deer, habitat impact, deer density

Prepared by: David Jackson, Extension Educator

Total Time Required for Lesson: Full class day for field trip and assessment activity.  1 hour for final assessment activity.

Setting: Outdoor woodlot and classroom

Topics: wildlife population management, browse impact survey, deer density

Goals for the Lesson

Upon Completion of this lesson students will be able to:

• Distinguish the difference between a wildlife population census and an index.

• Define population monitoring.

• Collect pellet group and browse impact survey data and calculate deer density per square mile.

• Relate deer density and browse impact to the health of the forest and deer population.

• Influence positive changes in deer management through a letter writing campaign.

Materials Needed (1 per group)

• 1.4.8.B Types of Writing – Write multi-paragraph informational pieces (e.g., letters, descriptions, reports, instructions, essays, articles, interviews). (PA State Standard Reading, Writing, Speaking, and Listening)

• 1.4.8.C Types of Writing - Write persuasive pieces. (PA State Standard Reading, Writing, Speaking, and Listening)

• 1.5.8.A Quality of Writing - Write with a sharp, distinct focus. (PA State Standard Reading, Writing, Speaking, and Listening)

• 1.5.8.B Quality of Writing - Write using well-developed content appropriate for the topic. (PA State Standard Reading, Writing, Speaking, and Listening)

• 2.2.8.A Computation and Estimation - Complete calculations by applying the order of operations. (PA State Standard Mathematics)

• 2.2.8.B Computation and Estimation - Add, subtract, multiply and divide different kinds and forms of rational numbers including integers, decimal fractions, percents and proper and improper fractions. (PA State Standard Mathematics)

• 4.3.7.C Environmental Health – Explain biological diversity. (PA State Standard Environment and Ecology)

• 4.8.7.D Humans and the Environment – Explain the importance of maintaining the natural resources at the local, state, and national levels. (PA State Standard Environment and Ecology)

• 4.9.7.A Environmental Laws and Regulations – Explain the role of environmental laws and regulations. (PA State Standard Environment and Ecology)

Methods: Hands-on, Field Trip and Investigating Environmental Issues

Doing the Activity

Background:

• In order to manage white-tailed deer populations wildlife biologists need to know the deer population in a given area.  Biologists need to know if populations are increasing, decreasing, or are stable.

• One way to determine deer populations is to perform a census.  A census is an exact count of every animal in a given area at one time.  An example of a census would be the aerial forward looking infrared flights (FLIR) that the Pennsylvania Bureau of Forestry has been doing on state forests.

• Often it is not possible to census the entire deer population.  In this case biologists may use a sampling method.  Sampling is not an exact count.  It is an estimate based on studying just part of the population.

• When it is not necessary to know the exact number of deer in an area a population index can be used.  An index does not result in an exact count of the animals that live in an area it just tells whether there are more or fewer animals than the last time it was checked.

• An index tells us how abundant animals are by counting signs.  Many types of animal signs can be used as long as each animal leaves them in roughly the same amount.  For deer, counts of their droppings can be used since each animal leaves them in roughly the same amount.

• Population monitoring involves using a census, sample, or index to determine how populations are changing over time.

• For this activity students will be using two survey methods: Pellet Group Counts and Browse Impact Surveys:

• Pellet counts are a population index that represents average deer density over winter.

• Browse impact surveys assess the level of browsing on forest tree seedlings and relates to habitat carrying capacity.

• Deer pellet counts and browse impact surveys must be conducted after snow melt but before spring green up.

• Surveys should cover as large an area as possible; preferably a deer’s home range (1 square mile or 640 acres).

• Survey area size can be adjusted dependent upon time constraints and woodlot size.

Doing the Activity: Field Trip

1. This activity will allow students to take a first hand look at habitat and compare it to deer population levels.  Students will perform two hands-on surveys simultaneously that will allow them to assess the deer population and deer habitat quality.

2. Begin by reviewing the protocol for pellet counts and browse impact surveys with the students and group leaders before the planned field trip.

3. Select a woodlot to study or visit a nearby public forest.  The objective is to study an area that is similar in size to the home range of a deer.

4. Have maps of the area prepared in advance showing the transect survey lines, length of lines, starting and ending points, as well as the compass bearings of the lines.  Public and private forestry and wildlife professionals may be able to assist you with this work.

5. Upon arriving at the study site divide students into crews and assign each an adult leader and a transect line upon which to collect pellet group and browse impact data.

1. Make crew assignments as follows: compass and pace navigator; data recorder/note keeper; plot measurer

Doing the Activity: Classroom

1. Upon returning to the classroom.  Combine the data collected from each transect line surveyed.  Calculate the deer density in numbers of deer per square mile. (formula is provided in protocol)

2. Have students compare the number of deer per square mile to the results of the browse impact study by having the students answer the following discussion questions.

3. How does the number of deer per square mile relate to the browse impact that was assessed on the observed tree seedlings?  Was the impact on the tree seedlings high or low?  Is the deer population in balance with the habitat (available food)?  Was there a plentiful amount of food available for each deer?  Were all the tree seedlings browsed the same amount or did the deer seem to prefer some tree species more than others?  In your opinion, did the area surveyed represent a healthy forest understory?  Why or Why not?  What does this mean for the regeneration of the future forest?   Based on this assessment of the habitat would the deer population be healthy in this area?  Would the level of browse impact observed affect other wildlife species?  If so, how?

Enrichment: Encouraging Positive Change

1. Discuss with students how deer management decisions in your state are made.

2. Deer management in Pennsylvania is governed by a commission that is funded almost exclusively through the sale of hunting licenses.  Are other wildlife conservation programs being addressed?  For example, endangered and other non-game species.

3. There are many people, besides hunters, whose views on deer management should be recognized.  Ask students to name them.  Some of these include: farmers, forest landowners, suburban communities, and environmental organizations.  What do you think their viewpoints would be?  How might they differ from recreational hunters?  Are their concerns being taken into consideration when deer management decisions are being made?

4. Do deer populations have an impact on your quality of life?  If so, how? Some examples might be: deer car collisions; health issues with deer ticks and Lyme disease; ability to grow certain species of landscape and garden plants; wildlife watching; and wildflower abundance.

5. What are some things that can be done to influence positive changes in deer management?  What kinds of changes will help to insure the forest is protected from over-browsing by deer?  Does the state wildlife management agency receive a broad base of funding support so that other wildlife species are addressed?  Do deer management decisions involve input from a broad range of stakeholders?

6. Have students write a letter to their state wildlife management agency.  Have students include in the letter how deer populations impact their quality of life.  Have them provide recommendations for positive change.  Mail letters to the appropriate agency.

Conclusion & Assessment (Evaluation)