Year 7 Science · Unit 1 · Lesson 18
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Learning Goals
Real-world context
Feral cats kill an estimated 377 million birds and 649 million reptiles in Australia every year (Woinarski et al., 2017, Biological Conservation). Australia has lost more mammal species than any other continent since European settlement. Many of these extinctions occurred on islands or in areas where cats were introduced alongside European settlers — places where native species had no prior experience with fast, silent predators.
(a) Using the five threat categories from the lesson, classify feral cats as a threat to Australian biodiversity. Explain your reasoning.
(b) Explain why island species are particularly vulnerable to threats like feral cats. Use lesson ideas in your answer.
Compare two
Complete the table to compare habitat loss and invasive species as threats to biodiversity.
| Feature | Habitat Loss | Invasive Species |
|---|---|---|
| How it affects species | ||
| Which ecosystems are most affected (Australian example) | ||
| Specific Australian example | ||
| Can the damage be reversed? Explain. | ||
| What can humans do to address it? |
1. The lesson states that threats "rarely act alone" and tend to stack. Use the koala as an example to explain how two or more threats can combine to make extinction more likely.
2. A farmer clears 500 hectares of bush in western NSW and replants 50 hectares with native trees, but in five scattered 10-hectare patches. Explain why this may not be enough to restore the biodiversity that was lost.
Wrap Up
In one sentence, what was the main idea of this lesson?