Uninvited Neighbors

Science · Animals of the World · ages 9-11

Name ______________________ Date ____________

Which squirrel is native to the UK?
- The red squirrel
- The grey squirrel
- Both are native
The lesson calls red squirrels the native wildlife of the UK. What does 'native' mean?
- They have lived there naturally for a long time
- People carried them there on purpose
- They were the first animals on Earth
Cane toads fixed Australia's beetle problem.
Circle one: True False
Which of these is a real example of an invasive species harming an ecosystem?
- Lions hunting zebras in Africa
- Salmon swimming upstream to lay eggs
- Grey squirrels outcompeting red squirrels in the UK
Insects hide inside fruit that people ship to an island. Nobody meant to bring them. The insects escape, spread, and eat the island's native plants. Are these insects an invasive species?
- Yes, because people moved them there and they are harming native wildlife
- No, because bringing them was an accident
- No, because insects are too small to be invasive
Grey squirrels invaded Australia, and cane toads invaded the UK.
Circle one: True False
This picture compares food left for red squirrels before grey squirrels arrived (left) and after (right). What does it show?
- Grey squirrels left plenty of food for red squirrels
- Grey squirrels left much less food for red squirrels
- Both squirrels always have the same amount of food
Grey squirrels arrived in the UK in 1870. Cane toads were brought to Australia in 1935. How many years after the grey squirrels did the cane toads arrive?
Answer: ______________
The lesson says an invasive species is moved to a place it 'could never have reached by itself'. What does that mean for grey squirrels?
- Grey squirrels never leave their nests
- Grey squirrels could not cross an ocean from North America without people's help
- Grey squirrels are too slow to walk anywhere
Squirrelpox barely affects grey squirrels, but it kills red squirrels. What does this tell you about diseases carried by invasive species?
- A disease that is mild for an invasive animal can be deadly for native ones
- Diseases only ever affect invasive species
- Red squirrels are the only animals that get sick

Answer key

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The red squirrel · Red squirrels have lived naturally in the UK for a long time. Grey squirrels were brought there by people.
They have lived there naturally for a long time · A native animal lives naturally in a place, and its kind has lived there for a long time.
False · The plan did not work. The cane toads barely ate any beetles, and then they spread across Australia.
Grey squirrels outcompeting red squirrels in the UK · Grey squirrels are not native to the UK. People brought them over from North America.
Yes, because people moved them there and they are harming native wildlife · It does not matter that nobody planned it. People moved the insects, and the insects are harming native wildlife, so they are invasive.
False · It was the other way around. Grey squirrels were brought to the UK, and cane toads were brought to Australia.
Grey squirrels left much less food for red squirrels · The amount of food dropped a lot, showing how grey squirrels outcompete red squirrels for the same food.
65 · 1935 - 1870 = 65. The cane toads arrived 65 years after the grey squirrels.
Grey squirrels could not cross an ocean from North America without people's help · Grey squirrels lived in North America, across an ocean from the UK. No squirrel could swim that far, so people must have carried them.
A disease that is mild for an invasive animal can be deadly for native ones · An invasive animal can carry a disease without getting sick itself, while native animals that catch it can die.