- Cataloguing limiting factors affecting populations of migrating animals.
- Predicting the effects of such limiting factors.
- Describing the effects of habitat loss and degradation on populations of migrating animals.
- Making inferences about the importance of suitable habitat for migrating animals.
Students role play animals migrating between breeding and wintering habitats and encountering hazards at each end of the journey.
Migration is a mysterious topic. How do birds and other animals travel often immense distances with such exactness? Some travel at night, some during the day, some in the skies, and others deep within the sea. Yet they locate habitats necessary for the continuation of their species. Scientists have proposed that they use the stars, the sun, and even the Earth’s magnetic field for guidance. Most probably, migrating species use a combination of means to guide their journeys. The purpose of this activity is to acquaint students with the idea that migratory animals need suitable habitat to provide them with food, water, shelter, and space in their breeding and wintering areas. Since these two locations are often thousands of kilometres apart, migrators also need appropriate habitat in between. In addition, students will dynamically experience some of the major factors affecting the survival of migratory species.
Large playing field or gymnasium; two paper plates for every three students; one extra paper plate for every three students if extension activity is conducted.
- Select a large playing field about 20 to 30 metres in length. Place paper plates in two patches on the playing field as shown below:
- Choose the number of plates so that you have one plate for every three students at each end of the field.
- Designate one end of the field as the “wintering habitat” and the other as the “breeding habitat.” You will have two sets of plates: one set in the breeding habitat and one set in the wintering habitat.
- In preparation for the activity, divide your class into four teams. Have each team study the animal profile of the eider, caribou, peregrine falcon, polar bear, or leatherback sea turtle under the menu item “Track Species in Space and Time” on our splash page at www.spaceforspecies.ca. Explain to the students that they will role play one, or all, of these migrators.
- At the playing field, explain that students will migrate between the wintering and breeding habitats at your signal. Tell them that the paper plates represent “suitable habitat” for migrating animals. At the end of a migration, each student will have to have one foot on a paper plate in order to be allowed to continue. If students cannot get a foot on a plate, that means they have not found any suitable habitat. They “die” and have to move — at least temporarily — to the sidelines and watch.
- Explain that many factors will limit the survival of populations of migrating animals. Some involve changes in wintering and breeding habitats. There will be times of abundant food, water, shelter, and space, all suitably arranged to meet the habitat requirements of a particular species. There will be other times when habitat is stressed, with many factors limiting the potential for survival. Sometimes, the area of available habitat will be reduced. Tell the students that, for the purposes of this activity, only three individuals can occupy a “habitat haven” (paper plate) at any one time.
- Begin the activity with all students at the wintering habitat. Choose just one of the species to role play. For simplicity’s sake, only eider migration is described in the following guidelines. Announce the start of the first migration of this sea duck. Have students migrate in slow motion until they become familiar with the process. For fun, have them flap their arms to simulate wings as they migrate. Then, they can speed up. On the first try, all eiders will successfully migrate to their breeding grounds.
- Explain that there has been no loss in the area of available habitat. Thus, a successful breeding season is at hand.
- Before students begin their return migration, remove one plate from the wintering area. Explain that a large expanse of habitat has temporarily changed: unfavourable winds and freezing temperatures have caused the formation of pack ice, which has closed off some areas of open water. Some birds will have nowhere to feed or rest. Repeat the instruction to migrate and send students to the wintering habitat. Have the three students that are temporarily eliminated stand on the sidelines. Tell students that these three “died” as a result of the loss of habitat.
NOTE: The series of migration cycles may be graphed as shown below.
- Before the next migration, remove four plates from the breeding area. This change represents a catastrophic habitat loss. Tell the students that this incident resulted from an oil spill. Then, instruct them to migrate. Many students will find themselves on the sidelines, waiting to re-enter the activity.
- Before many cycles are repeated, provide sidelined students with opportunities to re-enter the breeding area. During some migrations, give students examples of favourable changes in habitat conditions that would make it possible for them to survive. (See the table below for both favourable and limiting factors). Two students can be made permanent monitors to restore or remove paper plates to or from the breeding and wintering grounds as instructed.
- Repeat the process for at least eight cycles to illustrate changes in habitat conditions with resulting effects on migrating eiders.
- In discussion, ask students to identify the apparent causes of the eider’s population decline from year to year. Ask them to imagine what may be the major factors contributing to habitat loss and degradation. Ask them to make predications about the effects of these factors. Distinguish between shortand long-term effects. Distinguish between gradual and catastrophic changes. Have students identify factors that may limit the remaining species: the polar bear, peregrine falcon, caribou, and leatherback turtle. Ask students to support their hypotheses with evidence, seeking additional information through research if necessary.
- Ask students to summarize what they have learned about factors affecting the success of animal migration. List, discuss, and compare and contrast human-caused factors and environmental factors. Highlight those factors that students identify as posing the most significant long-term threats to the survival of migrating animals.
- What kinds of things can and should be done to protect and/or restore habitats for migrating animals? Discuss potential tradeoffs related to any recommendation.
- Conduct the activity again, but this time, include habitat used by migrating species between the breeding and wintering areas. During each migration, remove or restore plates under different habitat conditions.
- Explore the major factors that result in habitat loss and degradation, or gain and restoration, for one of the species. Research the causes of long-term habitat loss, as well as any major efforts under way to allay these impacts.
- There are national laws and international treaties protecting migratory species. What is their history? Are they effective? Which migratory species, if any, are not protected by such laws?
Factors Limiting Survival of Eider Populations
- Contaminants, such as PCBs and mercury, which reduce reproductive success and hatchling survival
- Death by suffocation of entire flocks and poisoning of food by oil spills
- Predation of adults, eggs, and hatchlings by eagles and gulls
- Illegal hunting
- Climate change
Factors Favouring Survival of Eider Populations
- Dynamic balance with predators
- Open water
- Favourable ocean currents and temperatures
- Restoration of habitat
- Regulation of hunting