Overview & Lesson Sequence

Focus on Standards & Assessment

Materials Needed, Preparation & Planning, Management Strategies

Background Info

Intro Activity
Why Study Predator - Prey interactions?

Activity 1
Observation of a predator-prey interaction

Activity 2
What makes a predator successful?

Research Project
Designing a predator - prey experiment

Optional Activity
Biological Control vs. Pesticides

Case Study
Rabbits in Australia

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Case Study: Rabbits in Australia

In this activity, students apply what they have learned in the previous activities to a new situation. If you have chosen not to do the optional activity (Activity 3), some of the concepts in this activity will be new to students.

You can make this activity as extensive as you want or have a one or two-day activity and discussion. Suggested procedures for each option are listed below.

The basic activity has students doing a case study of biological control. The case is the introduction, spread and subsequent problem of wild rabbits in Australia.  In studying this case, students learn what happens when a pest (the rabbits) have no natural predators and what measures were taken to control the population. They then apply what they have learned to address the questions (Basic Activity).

If you wish to extend the case study, students can explore the impact of the rabbits on the Australian environment and economy.  In addition, new controls being proposed, such as immunocontraception, can be discussed and their relative effectiveness debated. Connections can be made to a variety of ecological topics: immunology, parasitology, bioethics, biotechnology, marsupials and competition with their more biologically successful relatives, the mammals. The activity can also be integrated with social studies and history.

Class time required
Approximately 45 minutes to collect and organize information

20 minute for discussion

Materials needed
computer with Internet connection or materials downloaded from the website:
http://rubens.anu.edu.au/student.projects/rabbits

Basic Activity
Have students access and study the sections of the website: History of the European Wild Rabbit in Australia, and Myxomatosis. You may want all students to study the rabbit problem in Australia or have individual students study a different aspect of the problem and then bring the information together to address the following study questions:

What happened to number of rabbits shortly after they were introduced into Australia? (exponential growth - See Great Gravidity). Why did this occur? (No natural predators and seemingly unlimited carrying capacity; little competition from indigenous species.)

In what ways was the rabbit adapted for success? (Mainly rapid reproduction but also some behaviors such as burrowing and hiding in fallen logs.)

Why were the initial attempts to control the rabbits? (Rabbits reproduced faster that farmers could kill them with pitchforks.)

What is Myxomatosis? How and why was it effective? Why and how did its effectiveness change? What would happen to the effectiveness of Myxomatosis if there had been an extensive program in Australia to exterminate fleas and mosquitoes? (Myxomatosis is a form of biological control. It was initially very effective but as the rabbits became immune, their numbers increased again. It was, and continues to be, a largely effective means of biological control. If fleas and mosquitoes were exterminated, there would be no carriers for the myxoma pox virus that causes the disease in rabbits.)

How does the case study of rabbits in Australia highlight issues of predator-prey relationships in an ecological system? (The overpopulation of rabbits and destruction of habitat highlights the need for balance in ecosystems and the important role that predators play in keeping that balance. Why have food chains evolved and why are they are so critical to ecosystem equilibrium.)

Who were the predators and who were the prey in this scenario? (Rabbits are both--"predators" of the vegetation and a natural form of prey in other ecosystems that kept their numbers in check. In this example, the myxoma pox organism is the parasite, which humans introduced into the system (see the information on Bt and parasites in the Background Information section of this lesson.)

How did human intervention affect the ecosystem balance in Australia? What other examples of human intervention have altered the balance of predators and prey in an ecosystem (feral cat populations - the result of not spaying/neutering pets and abandoning them - impacts local bird and rodent diversity in many parts of the world; the Vedalia beetle was introduced from Australia to control another introduced pest, the Cottony-Cushion scale, which was decimating citrus in California.  Insect growth regulators (IGRs) were applied to citrus crops to kill the scale insects, but also killed the beneficial beetles leading to an increased infestation of the scale insects.)  Note that this question leads very nicely to the agricultural issues of monoculture and pesticide use.

Extended Activity
The extended activity can be done in a variety of ways. You may want to assign students different roles such as farmer, hunter, researcher specializing in biological control, local politician, animal conservationist, ecologist, member of an animal welfare organization or have them choose their own roles. Alternatively, you could have students look at the rabbit problem from various points of view.  Different teams of students may want to do different activities, for example, one team of 10 may want to do role playing, another team of six may want to have a panel discussion, a third team of eight might want to develop a pamphlet or television program (if they have access to a media lab) to educate the public about the complexity of the rabbit problem.

Begin with the website on rabbits including the Basic Activity and sections on Immunocontraception and Impact of the Rabbit in Australia. From there, students may also want to access other websites to complete their research. Focus students’ research on effects of rabbits on the environment, lack of natural predators, and methods of biological control based on the rabbit population problem.

Conduct a discussion addressing the "big ideas" posed by the case study.  What are the main concerns when introducing a species into an environment when there are no natural predators or predators are destroyed?  How is this similar to an agricultural crop grown as a monoculture?

Assessment
As students research, present, and discuss the rabbit problem in Australia, use the Observation Check sheet to record students' attainment of the learning objectives.  Review students' journal entries and/or presentation materials to determine what levels of conceptual understanding they are developing.  You may also want to use a presentation rubric to assess their posters or presentations (see Rubric for Group Presentations).  At this point in the lesson, students should be able to explain the role of predators and parasites in an ecosystem and describe how humans can alter the natural balance of an ecosystem. 

As an additional assessment, have students write in their journals or present to the class an essay on the following question: What might happen if a natural predator (i.e. a coyote or bobcat) was introduced into Australia to control the rabbit population? (this would have devastating effects on Australia's unusual wildlife; students should be able to suggest outcomes of the hypothetical predator-prey relationship and effects on the environment.)

For a performance-based assessment, students could develop a plan to control a pest species in the school's vegetable or butterfly garden, greenhouse, or, if your school doesn't have an outdoor space, a pest problem within the school's buildings (i.e. a problem with roaches or crickets.)