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13.3: Activities and Answer Keys

Difficulty Level: At Grade Created by: CK-12
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Activity 12-1: Design a Nature Reserve


Summary Students apply their knowledge of ecology and biodiversity to a real-life conservation problem by designing a nature reserve for an endangered species, the Kirtland's warbler.



\begin{align*}\checkmark\end{align*} explain the habitat requirements of the Kirtland's warbler.

\begin{align*}\checkmark\end{align*} describe the interaction between the warbler and the cowbirds.

\begin{align*}\checkmark\end{align*} describe the impact humans have on the survival of the Kirtland's warbler.

Student Materials

Per student

  • Resource 1
  • Resource 2

Per group

  • Butcher paper
  • Marking pens or colored pencils

Teacher Materials

  • None

Advance Preparation

You may want to get maps of the region in Michigan where the Kirtland's warbler is found. You can obtain the topographical map for Mio, Michigan, from the U.S. Geological Survey. Before you begin, read over the information on the Kirtland's warbler on Resource 1 and Resource 2.

Estimated Time One to three 50-minute periods

Prerequisites and Background Information

Students should have a basic understanding of the terms species, habitat, and endangered.


Introduce Activity 12-1 by discussing the terms species, habitat, and endangered. Ask students if they know of any endangered species. Write correct responses on the chalkboard.

Helpful Hints

Point out to students that the process of research and planning they are using is similar to how biologists actually plan and design nature reserves. Explain that inappropriately planned and designed nature reserves are often unnecessarily expensive, costly in lives of the threatened species, and unsuccessful. Therefore, the design of nature preserves is the subject of increasing concern and research.

As an alternative way for students to present their reserve plans, you can set up a“funding committee,” which will determine which group has the most efficient and effective reserve plan. Students submit their proposals as well as a presentation, and the “funding committee” can make its decision based on predetermined criteria.

Steps 1-2 Have students design their reserves according to the activity instructions. Encourage them to be as accurate and as realistic as possible, especially considering that funding for reserves is usually very limited. This project can be quick or very in-depth. So make time limits clear while students work.

Schedule the presentations and guide students as they present their papers to the rest of the class.

Conclude Activity 12-1 by discussing the differences and similarities between the groups' designs for the same species. You may want to include the following questions in the discussion:

  • Which design is more inclusive of the warbler's habitat requirements?
  • Which design is more economical?
  • Which design will be the least controversial with regards to human needs?

Extend Activity 12-1 by

  • Including basic map reading skills as well as map drawing. Students can use topographical maps from the U.S. Geological Survey and/or road maps to locate and draw the area covered by their reserve. Students can locate areas of human impact in relation to the remaining habitats of endangered species.
  • Having groups of students research different endangered species and produce case studies explaining the habitat requirements of the species and its other characteristics. Have the groups trade case studies and develop appropriate reserve plans. Afterward the groups that originally researched the species can critique the reserve plans prepared by their classmates.


Use the nature reserve plans to assess if students can

\begin{align*}\checkmark\end{align*} identify the specific habitat requirements of the Kirtland's warbler.

\begin{align*}\checkmark\end{align*} demonstrate and explain how humans can conserve species by carefully managing a reserve.

Review Questions/Answers

  • Sample answers to these questions will be provided upon request. Please send an email to teachers-requests@ck12.org to request sample answers.
  1. What is the difference between a proximate and an ultimate cause? How does this apply to the causes of extinction of a species?
  2. What are nature reserves? How do they help prevent the loss of biodiversity?
  3. If the Department of Parks put a wire fence around an empty lot in your town and claimed that it was a reserve for grizzly bears, would you say that the reserve designers had done a good job or not? Why or why not?

Activity 12-1 Resource 1: Design a Nature Reserve (Student Reproducible)

Case Study of the Kirtland's Warbler (Dendroica kirtlandii)
Time Status

\begin{align*}\rightarrow\end{align*} People cut down large areas of forest in the midwestern United States.

\begin{align*}\rightarrow\end{align*} Loss of mature, fire-resistant forest leads to many forest fires.

\begin{align*}\rightarrow\end{align*} Forest fires allow growth of new forests of jack pine in southern Michigan.

\begin{align*}\rightarrow\end{align*} Populations of Kirtland's warbler, normally rare, expanded into their increased habitat.

\begin{align*}\rightarrow\end{align*} Clearing of forests also benefits the brown-headed cowbird, a nest parasite that lays its eggs in the nest of a host bird and then leaves. The eggs of the host bird do not survive in this process.


\begin{align*}\rightarrow\end{align*} People fear losing houses, crops, and timber and begin routine efforts to stop and prevent forest fires.

\begin{align*}\rightarrow\end{align*} Without fires, jack pine forests mature beyond the point at which warblers will nest in them.

\begin{align*}\rightarrow\end{align*} The forest fire prevention that helps humans survive also greatly reduces the warbler's habitat.

\begin{align*}\rightarrow\end{align*} Food supply for cowbirds is now more plentiful because of the mechanical harvesting of grain.

\begin{align*}\rightarrow\end{align*} Cowbirds are no longer limited by the scarcity of food in their wintering range.

\begin{align*}\rightarrow\end{align*} Cowbird populations spread and increasingly parasitize the nests of Kirtland's warblers. This causes a decline in the warblers' reproductive success.

1961 \begin{align*}\rightarrow\end{align*} Five hundred nesting pairs of Kirtland's warbler are scattered through 16,000 square kilometers (6,200 square miles) of forest.
1967 \begin{align*}\rightarrow\end{align*} Kirtland's warbler is listed as an endangered species under the federal Endangered Species Act.

\begin{align*}\rightarrow\end{align*} An intensive program begins to trap cowbirds.

\begin{align*}\rightarrow\end{align*} This trapping program results in a 65 percent drop in nest parasitism, leaving only about 5 percent of the warbler nests affected by cowbird parasitism.

\begin{align*}\rightarrow\end{align*} Four times as many baby warblers survive to leave the nest.

1976 \begin{align*}\rightarrow\end{align*} The U.S. Forest Service begins expanding warbler habitat by cutting jack pines.

\begin{align*}\rightarrow\end{align*} Two hundred nesting pairs of the warbler now live in 3,400 square kilometers (1,300 square miles) of forest.

\begin{align*}\rightarrow\end{align*} The warbler will not be out of danger of extinction until there are at least 1,000 breeding pairs, according to the Office of Endangered Species.

\begin{align*}\rightarrow\end{align*} 265 singing males are counted. This large increase is attributed to increased habitat areas created by a wildfire in 1981. The young jack pines grow to a suitable nesting size.


\begin{align*}\rightarrow\end{align*} 485 singing males are counted.

\begin{align*}\rightarrow\end{align*} The U.S. Fish and Wildlife Service removes 4,600 parasitic cowbirds.

1994-1995 \begin{align*}\rightarrow\end{align*} A record number of jack pine seedlings-4.5 million-are planted by the Michigan Department of Natural Resources and the U.S. Forest Service on about 2,500 acres.

Activity 12-1 Resource 2: Design a Nature Reserve

Background Information on Kirtland's Warblers

The Kirtland's warbler is a small, colorful songbird. It's about 14-15 centimeters long and has a short, stout bill. Adult males have an upper body of bluish gray with black and white markings and dull yellow underparts streaked with black. Adult females have an upper body of bluish gray with streaks and underparts of pale yellow with a speckled breast.

Kirtland's warblers nest and raise their young during the summers in the northern Lower Peninsula of Michigan. Every winter they fly to the Bahamas, a group of islands off of Florida. The trip to the Bahamas is so long that the birds must stop along the way to rest. These resting spots are important to the birds and must include the ecological requirements necessary for survival. Food requirements for Kirtland's warblers include a plentiful variety of insects. Kirtland's warblers often like to hover at the ends of branches in order to pluck insects out of pine needle clusters. They also eat berries.

The warblers generally lay five eggs. The eggs hatch about the middle of June. If there are no predators, the average number of surviving warblers can be as many as four fledglings per adult pair. However, the brown-headed cowbird (Molothrus ater) lays its eggs in the nests of other birds including the warbler. The warblers do not realize they are incubating cowbird eggs. The warblers then care for the cowbird eggs as if they were their own. When the baby cowbirds hatch, they grow quickly at the expense of warbler chicks. The result is a decrease in numbers of fledgling warblers and an increase in numbers of fledgling cowbirds. If cowbirds are allowed to breed unchecked in warbler territory, the nesting success of warblers can average as low as 1.4 new fledglings per-season. This reproduction rate is not high enough to support a continuing population of warblers.

The Kirtland's warbler has very specific habitat and breeding requirements. A breeding pair of Kirtland's warblers requires a territory of about 12 hectares (30 acres) of young jack pine habitat that has many small areas, few or no hardwood trees, and minimal ground cover. Jack pines are a species of pine tree (Pinus banksiana) in which the warblers build their nests. A jack pine forest must be at least 30 hectares (74 acres) or more in area in order to be large enough to support breeding warblers. In the past, forests of jack pine caught fire periodically and burned. The fires stimulated the growth of new jack pine so there was a continuous natural renewal of jack pine forests.

The Kirtland's warbler requires stands of young jack pine trees about 2 to 6 meters high (about 8 to 21 years old). The warblers will live in a young forest until it becomes too old (about 6 meters high) and then move to a new, younger jack pine forest. However, more recently, humans have tried to control forest fires for their own protection. As a result, the growth of new jack pine forests has declined. This decline in jack pine forest renewal has caused a decline in suitable breeding habitats for the warbler. The result has been a decrease in the number of warblers.

There is not much information available about the warbler's preferred winter habitat in the Bahamas. There is some indication that the birds require low, broad-leafed scrub, which is the main form of natural vegetation on the islands. With the development of homes and resorts on the islands, the natural vegetation is being cleared. While the habitats along the way to the Bahamas must also be suitable for warblers, there is little information known about these sites.

Once a population of warblers declines to a certain size, there is little hope of saving that population from extinction. In order to introduce a population of warblers into a new area, one ought to plan for a habitat capable of supporting 250 breeding pairs.

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Date Created:
Feb 23, 2012
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