Invasive Species

Invasive species are organisms that successfully establish, and then thrive, in new environments.  An invasive species can be a micro-organism that causes disease;  a plant or animal that competes with a native species for resources (like food or space); a predator of native species; and/or an organism that alters the way an ecosystem works.

Why are invaders a threat?

Invasive plants and animals can:

• kill native species
  
  
• compete with native species for food and space
  
  
• spread new diseases and parasites to native species

Invasive species, together with habitat destruction, have been major causes of the extinction of native species throughout the world in the past few hundred years.

Snakes have sometimes arrived in New Zealand as stowaways, but have not yet established here.

How do invaders get to new areas?

Aliens invade new areas in two ways.  Most are transported by humans (either on purpose or accidentally), but some make their own way (e.g., blown by a storm).  Stowaways can hitch a ride in:

• vehicles (ships especially in ballast water, planes, trains, trucks, etc)
  
  
• shipping containers
  
  
• packing materials
  
  
• travellers luggage
  
  
• mail/parcel freight
  
  
• agricultural produce

What can we do to prevent invasion?

• Keep them out: The first line of defence against invaders is not to allow them into the country in the first place
  
  
• Detect new arrivals early: Needs regular searching near airports and ports
  
  
• Eradicate them:  May be difficult and expensive
  
  
• Control them:  If eradication is impossible, it may be possible to control them enough to reduce the damage they do to our environment

The Ministry of Agriculture and Forestry (MAF) is responsible for New Zealand's biosecurity (i.e. protecting New Zealand from alien invaders).