On a Wing and a Prayer
Lesson Introduction
The cowbird is a bird that parasitizes other species of birds by laying eggs in the other bird's nests. Its survival depends on the songbird raising its young. When two different species have a relationship in which one species directly benefits from the other, the relationship is symbiotic.
There are three types of symbiotic relationships: Mutualism is one in which both species benefit. Flowers are a good example since many insects, birds and bats rely on their nectar to survive. While obtaining nectar, they pollinate flowers and promote reproduction. Commensalism, a relationship in which one species benefits but the other is not harmed. For example, remora fish attach themselves to sharks, and travel with them, feeding on the shark's leftovers. The shark is neither harmed nor helped. Finally, parasitism (definition), is a relationship in which one species benefits and the other is harmed. Ticks attach themselves to deer and feed on their blood. This is harmful to the deer. The relationship of the cowbird and the songbird is another example.
Many of Illinois' forests have been broken into small fragments because of human development. Agriculture and roads are two major reasons cited in the video, On a Wing and a Prayer. In this lesson, students discover the strong connection between development, deforestation (definition), and the population of songbirds, in terms of the cowbirds and their parasitism.
Grade Level
4 through 10
Objectives
The students will:
1. define symbiosis, mutualism, commensalism and parasitism.
2. classify animals and plants from each type of symbiotic relationship.
3. create a pair of animals that has a symbiotic relationship and define that relationship.
Time Allotment
two 40-minute sessions
Materials
six animal Relationship Cards, one set for each pair of students
paper or craft materials (i.e., construction paper, pipe cleaners, plastic eyes, brads, glitter, etc.)
video/video player
Books to Read
Nonfiction
Backyard Birds of Summer, by C. Lerner, New York, NY: Morrow Junior Books, 1996.
Birds Over Troubled Forests, by Smithsonian Migratory Bird Center, 1991.
Birdwise, by P. Hickman, Reading, MA: Addison-Wesley Publishing Company, 1995.
Children's Guide to Birds, by J. Johnson, New York, NY: Simon & Schuster Books for Young Readers, 1996.
Everything You Never Learned About Birds, by Rebecca Riepp, Pownal, VT: A Story Publishing, 1995.
Fiction
Song of the Swallows, by L. Politi, New York, NY: Charles Scribner and Sons, 1949.
Who Really Killed Cock Robin: An Ecological Mystery, by J. Craighead George, New York, NY: Harper & Collins Publishing, 1970.
Advanced Preparation and Teacher Notes
Create sets of animal pair cards for each pair of students. Invite a few students to help you by illustrating the animals. Collect paper and craft materials available for the students to use. Arrange students in pairs.
Procedure
Tap Prior Knowledge
1. Ask students if they know of any animals or plants in nature that rely on another species to help them survive. Show the section of the On a Wing and a Prayer video (from 33 45 to 37 39) which highlights cowbird parasitism in action.
Share with Neighbor/Revise Ideas
2. Let students discuss their examples of animals and plants. Tell students about the six different examples of symbiotic relationships and give them the animal/plant relationship cards.
3. Have students work in pairs to discuss the different types of relationships, and create a classification system for grouping them. Hold off on giving definitions so the students can develop their own classifications.
4. Have a class discussion on how the students classified the variety of relationships. Discuss the different classification systems that the students developed.
Engage Students in a Hands-on Activity
5. Working in pairs, the students create an imaginary pair of animals and/or plants that depend on each other in some way. These can be student drawings or 3 dimensional constructions of plants and animals. Remind students to focus on how the animals and/or plants interact. Do they help each other, is only one helped, or is one helped while the other is harmed?
6. Have the students write a short description telling about the relationship between the two creatures they created. The description should name each animal or plant, describe the important characteristics, and explain the relationship between the animals and/or plants. Finally, the students should tell who benefits or is harmed from this relationship.
Introduce the Scientific Principle/Concept
7. Discuss the three types of symbiotic relationships and who benefits or is harmed by each. Discuss the differences in mutualistic, commensalistic, and parasitic types of symbiosis. Give the students the definition of each of these words as outlined in the introduction.
8. Use the cowbird as an example. The female removes one or more eggs from a nest and replaces them with her own eggs. The eggs of the cowbird often hatch earlier than the host bird's own eggs, and the cowbird nestlings are larger then the host's so they get most of the food. Cowbirds are able to lay 30-40 eggs in a breeding season, so one female cowbird can parasitize 30-40 nests in a season.
Connect to Other Everyday Examples
9. Human diseases are often the result of parasitic relationships. Bacteria, viruses, fungus and parasites invade the body and cause diseases. The common cold is caused by Rhinovirus which infect mucus cells lining the nose, throat and lungs. Strep throat is caused by the Streptococcus bacteria. There are other bacteria that live in the body that neither help nor harm us, and some bacteria that may be helpful to us. Fecal coliform bacteria are naturally present in the human digestive tract, and aid in the digestion of food.
10. People engage in symbiotic relationships that could be categorized as mutualistic, commensalistic and parasitic. A mutualistic relationship might be that of students and teachers, students learn from teachers and teachers earn their living. A commensalistic relationship might be venders at a ball park. The ball park brings in the crowd and the venders are able to sell things to them. The ball park is not helped or harmed by the venders. A parasitic relationship might be thieves. They get something that belongs to someone else and that person is harmed. This could be used as a foundation for a discussion with students.
Lesson Assessment
11. Create a symbiosis bulletin board by dividing the board into three sections one for each type of relationship, mutualistic, commensalistic and parasitic. Have a heading and definition for each section of the board. Have the upper portion of the board show real symbiotic relationships found in nature (you can use the relationship cards). Then have the students place their created animals and plant relationships on the bulletin board in the appropriate place.
12. Use a holistic scoring guide to grade the students work.
Extension Activities
13. Have students read books or articles that give additional information about symbiotic relationships. Have the students work in small groups to discuss the readings. Assign each member of the group a role to play in the group. Some roles could include; summarizing the article, providing discussion questions, finding definitions for unfamiliar vocabulary, high lighting careers, picking a passage to read and discuss.
Students could then read Aesop's Fables and discuss the fictional relationships of these animals and compare them to real symbiotic relationships found in nature. Some stories that would work with these concepts include The Lion and the Mouse, The Wolf and the Crane, and The Fox and the Crow.
Books to use for extension activity:
The Fables of Aesop, by Joseph Jacobs (Editor), New York, NY: Schocken Books, 1966.
Parasites, by Howard and Margery Facklam, New York, NY: Twenty-First Century Books, 1994.
Symbiosis: Nature in Partnership, by Nicolette Perry, London, England: Blandford, 1983.
14. Give students a chance to surf the World Wide Web for more information about forest fragmentation and the problem of the cowbirds:
