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Unwelcome visitors
 When we travel, animals and plants travel along with us. Sometimes we transport them on purpose. 
In 1788, Australian settlers imported some rabbits. Some were bred in cages and eaten. Others were released so that locals could go out later and hunt them.
Within a few years, wild rabbits were everywhere. More  than 2 million were killed in one year - leaving millions more running wild. 
Sometimes animals and plants hitch a ride by accident. In the 1940s, a brown tree snake from Australia went to Guam Island in an aeroplane cargo hold. Moving creatures into new areas can be very dangerous. The visitors compete with native creatures for food and space. If the visitors have no enemies, they breed too quickly and take over. 
Non-native plants and animals that kill off local species are called invasive species. The brown tree snake in Guam and the rabbits in Australia did lots of damage.
The snakes killed off five out of eight native Guam bird species. The rabbits in Australia killed off tall grasses, destroying the food and breeding sites of dozens of small mammals and seabirds. 
Travelling is a lot of fun but bringing along animals and plants is a dangerous business.
 True or False?
 1 Invasive species are foreign visitors that kill native species.
 2 Australian snakes killed off five bird species in Guam.
 3 European rabbits destroyed grasses in Australia.
Shipping in trouble
 Fill in the gaps with the following words:  spread, hollow, pests 
 Ships carrying cargo have _______________ panels in their hulls that can be filled with water. This ballast water helps balance the ship. The problem is that ballast water can contain plants, animals and bacteria. 
In 1980, a ship dumped ballast water with South American black-striped mussels in Hong Kong. Within a short time, the invading mussels _______________ over Victoria Harbour. 
Because these little creatures are the size of a finger-nail, they clog pipes and drains. It took a lot of work to remove these _______________.
Other pests arriving in the same way include Mediterranean mussels, sea squirts from the US, and algae that causes paralytic shellfish poisoning.
American cockroach
 Find words that mean:  the whole lot, not easy, quick
 The American cockroach comes from the forests  and fields of Africa where the temperature is about  29 degrees Celsius.
These insects eat everything from plants to fleas to cardboard. Although they are 5cm long with bright red-brown bodies, these cockroaches are difficult to spot. This is because they can run at 5.4km/h. 
Although we can run at this speed, too, we are a lot bigger. If we wanted to move as fast as a cockroach, we'd have to run at 330km/h. This fast cockroach has hitchhiked on boats, planes and ships. It now lives inside heated buildings all over the world. It even lives on the 20th floor of Hong Kong apartments!
Mile-a-Minute pest
 Link the underlined words to the correct antonyms, words that mean the opposite: slowly, make friends with, ugly
 The Mikania vine from South America has very pretty white flowers. Because it's so pretty, it was planted by gardeners in many places, including Hong Kong. 
Unfortunately this plant grows very quickly. It can grow 8cm in 24 hours. When it grows, it just spreads over other plants - and chokes them!
Because it spreads too quickly, the Mikania is nicknamed the Mile-a-Minute. Originally a nice garden plant, it has spread into the countryside, killing native plants and crops. 
The Mikania is now one of the three worst pests in Indian and Indonesian tea plantations. It also kills rubber plants in Sri Lanka and Malaysia. 
Farmers grow Cuscuta plants and Puccinia mushrooms on the edges of fields to fight off the Mikania. But stopping the Mile-a-Minute  isn't easy!
Aliens in Hong Kong
  Crab-eating macaques come from Malaysia, Indonesia and the Philippines. Since they were introduced into Hong Kong, they have become a problem. 
These monkeys compete with native birds for fruit. They also eat  the eggs and chicks of endangered  forest birds. 
Macaques are very cheeky and can be aggressive towards people. They can be pests in public parks such as Kam Shan, Lion Rock, Shing Mun and Tai Po Kau reserve. 
Rock pigeons are originally from Europe. They were released all over the world, including Hong Kong, as a game bird. Today their droppings damage buildings and monuments everywhere. They also transmit various diseases to chickens and local wildlife.
Other common aliens include crazy ants, house crows, water hyacinths, cannibal snails, Japanese honeysuckle and oyster plants.
compare!
Think wars kill a lot of people? The Asian tiger mosquito hitchhikes around the world inside damp car tyres. It spreads disease to half a billion people a year and kills 1 million more
fab fact!
In 1840, Australian companies imported camels. They used these animals to transport people and goods through the country's desert interior. But some camels escaped. Today there are more than 1 million feral camels in Australia's deserts
fab fact!
In 1890 Eugene Schieffelin released 60 English starlings into New York City's Central Park. They now number   200 million and compete with native American birds
now do this 
Answer the following questions without  referring to the text
1 Black-striped mussels travelled to Hong Kong ...
a. by plane as pets
b. by ship in ballast water
c. inside car tyres
2 American cockroaches are native in ...
a. North America
b. South America
c. Africa
3 Mile-a-Minute is a/an ...
a. fly from India
b. plant from South America
c. animal from North America
4 Rock pigeons spread because ...
a. people like to hunt them
b. people had them as pets
c. because they eat insects
5 Starlings are a ...
a. native species in the US
b. native species of West Africa
c. Native species of Europe
6 Camels were imported to Australia ... 
a. on purpose as transport animals
b. by accident when a circus caught fire
c. on purpose so people could hunt them
Look online for more about invasive species
Nab the Aquatic Invader
http://www.sgnis.org/kids
Become a super sleuth, check out the suspects, and decide on who to arrest as an illegal alien!
NG Invasive Plants
http://kids.nationalgeographic.com/Stories/
SpaceScience/Invasive-plants
A special from National Geographic on plants that leave home and cause problems abroad.
Top 100 Invasive Species
http://www.conservationinstitute.org/invasivespecies.htm
It?s not a pretty site, but it lists the world?s worst aliens.
Great for homework projects.



Alien invaders