Lesson Plan

Unit 2 — PEST INVADERS

Activity — Unwelcome visitor

Setting the scene

Students are provided with the following scenario.

Hundreds of exotic prickly acacia plants (a noxious weed introduced from Southern Africa) have established on a farm located in northern South Australia. As a result, the farmer has a number of problems including:

a reduction in suitable grazing for his sheep
damage to the sheeps’ fleece
damage to new born lambs
inability to use working sheep dogs due to many thorns on the ground
the restricted use of horses and motor cycles due to dense thorny thickets
the prevention of sheep accessing water points.

Over the years chemical sprays have reduced the spread of the prickly acacia but recently many plants are showing signs of resistance to the chemicals and are now starting to spread to adjoining properties. Bulldozing and burning only encourages the prickly acacia to spread its seeds.
The only animal known to kill prickly acacia is the giraffe. In Africa the prickly acacia is a favourite meal for the giraffe who will often remove all of the leaves which then kills the plant.

The farmer has applied for a permit to import 20 adult giraffes and five young to assist in the removal of prickly acacia.

Aim

Students form an understanding that Australia continues to be under threat from the invasion of new pest animals.

Student outcomes

Students will:

understand that risk assessment processes play an important role in reducing the likelihood of new species establishing as a pest in Australia
recognise that imported animals have the capacity to become a pest
understand that domestic, exotic and livestock animals already within Australia have the capacity to become a pest
apply criteria that have been developed to assess an exotic species’ ability to become a pest
understand the characteristics that make an effective a pest animal
complete basic research and retrieval of information
understand and carry out detailed written instructions

Materials

What to do

This activity is also suitable for students working together in small groups.

Note:

Hand out the:

activity sheet
giraffe fact sheet
pest assessment guide
pest answer sheet

Step 1

Introduce the topic by discussing the ‘setting the scene’ section of the activity with your students.

Step 2

The instructions for this activity are quite detailed so review the activity with your students and identify when to use each additional hand out.

Step 3

Record all of the students’ answers to the question:
Do you think giraffes are capable of becoming a serious pest animal in Australia?
You may like to encourage each student to explain the reason behind their answer.

Step 4

Students use the giraffe fact sheet to complete the pest assessment guide.
Be aware that all of the answers are hidden in the giraffe fact sheet.

Step 5

Students transfer their pest assessment guide scores to the pest answer sheet.
The final answer to this activity may vary slightly depending on student opinion and interpretation.

The most common answers to this activity are:

Pest assessment guide

Risk to public safety

harm to people	injuries or harm severe or fatal and few people at risk	4
harm to property	unknown damage potential	3
spread disease	all animals are likely to spread disease	2
Total score A		9

Risk of creating a wild population

babies	less than 4 babies a year	1
diet	an animal that is a grazer (eats grass and other low plants) or browser (eats leaves, buds and seeds from shrubs and trees)	3
Total score B		4

competition with native animals for tree hollows	does not nest or shelter in tree hollows	0
home	can only live in undisturbed (natural) habitat	2
Total score C		2

overseas environmental damage	the animal causes major environmental damage in an overseas country	3
overseas crop damage	the animal causes minor damage to crops in an overseas country	2
Total score D		4

Risk of becoming a pest

overseas distribution	found in an area 10–30 million square kilometres	1
migration pattern	does not migrate	1
Total score E		2

babies	less than 4 babies a year	1
diet	an animal that is a grazer (eats grass and other low plants) or browser (eats leaves, buds and seeds from shrubs and trees)	3
Total score F		4

competition with native animals for tree hollows	does not nest or shelter in tree hollows	0
home	can only live in undisturbed (natural) habitat	2
Total score G		2

overseas environmental damage	the animal causes major environmental damage in an overseas country	3
overseas crop damage	the animal causes minor damage to crops in an overseas country	2
Total score H		4

Pest answer sheet

	Scores	Total	Level of risk
risk of becoming a pest	E + F + G + H	12	HIGH
risk of establishing a wild population	B + C + D	10	HIGH
risk to public safety	A	9	EXTREME
The risk of giraffe becoming a pest animal in Australia is		EXTREME