The Antipodes Islands have a million dollar mouse problem. The house mouse (Mus musculus) was first introduced to the islands in the middle of the 20th century. They were first discovered in cast-away depots and recent genetic studies have revealed that their ancestry is in Spain. It’s thought that they escaped from a Spanish ship that was wrecked nearby.
While mice are widespread on the main Antipodes Island, two of the northern islands (Bollons and Archway Islands) have not been colonized. This is great news for scientists doing studies on mouse behaviour as it allows them to compare the flora and fauna of the northern, mouse-free islands with the infested southern islands. These kinds of studies have revealed alarming rates of decline in certain species and allow scientists to fully understand the impact that mice are having on the wildlife and plant life on the islands.
When mice are the only mammalian inhabitants of an island they are known to behave like rats. They are more aggressive and will take larger prey than their mainland counterparts and that is the biggest problem – mice will eat anything. A large number of seabirds visit the Antipodes Islands to nest and feed. Mice will prey on small birds, their eggs, and chicks and seabirds are more vulnerable because they make their nests on the ground in large colonies – a scene that must seem like a buffet to the house mouse. This is especially dangerous in the Antipodes, as it is home to a number of birds that are found nowhere else in the world such as the Antipodean albatross, Antipodes Island parakeet, and Antipodes Island snipe. It’s also home to half the worlds population of erect-crested penguins.
Mice are also a serious threat to the invertebrate community in the Antipodes Islands. The islands entomology is not well understood, mostly due to the islands remote location. The first recorded insect collections were made by Professor F. Hutton when he visited the island in 1901. A few brave researchers have studied insect populations on the islands and what they do know is that populations are larger and more diverse on northern, mouse free islands. Scientists also discovered an un-described species of weta (known as Orthoptera) on the northern islands, which could be a reflection on either the absence of mice or a difference in habitat. It has also been shown that mice will eat larger numbers of invertebrates at higher altitudes, meaning the higher you go, the less insects you will find.
Large numbers of juvenile mice were found in areas with a large number of plants, especially in coastal areas. This is because breeding is fueled by seeds of species such as Carex (sp.) and Poa (sp.), which are eaten by the juveniles. These plant species have not evolved any natural defense to mammalian browsers and so their reproduction and ability to re-colonize the island is impaired.
So there you have it – I have introduced a problem – a serious threat that are able to do incredible harm to our biodiversity. But what’s the solution? We know it’s possible to eradicate all mammalian predators from vulnerable Sub-Antarctic Islands. In fact we’ve done it – both Campbell and Enderby Islands are now free of pests thanks to carefully designed eradication programmes. The question is what will it cost and who is going to pay?
Cue the Antipodes’ knight in shining armour – Gareth Morgan, a New Zealand businessman who recently led the Our Far South expedition to raise awareness for the Southern Ocean. He launched the million dollar mouse campaign earlier this week and wants to remove mice from the islands for good.
His goal is to raise 1 million dollars and so Gareth is matching all public donations dollar for dollar. The Department of Conservation will use the money to employ a four day aerial poisoning tactic and will use helicopters to distribute it all over the island – ideally targeting the home range of every mouse on the island. If it’s successful, the wildlife, plants, and birdlife on the island will be safe from predation on their island sanctuary in the Southern Ocean.
In light of this fantastic initiative, I decided to get out on the streets & shake the bucket around to try and rouse some support from my friends & family. I’ll keep you posted on how much I can raise – and it’s even more encouraging to know that whatever number I come up with, Gareth will double it. Wish me luck!