The Mega-Herbs of Macquarie Island are Back in Bloom!

I feel as though I have been writing about the effect of pest species on the Sub-Antarctic Islands a lot as of late and so when I saw the topic for this blog post, I couldn’t help but share it. Who doesn’t love good news?

ECOS Magazine recently reported that the large-scale operation to eradicate rabbits from Australia’s only Sub-Antarctic Island, Macquarie Island, is already doing good things for its wild inhabitants.

The article, Macquarie Island is Back in Bloom, tells of ecstatic scientists who have watched the islands mega-herb populations take over the island quicker than anyone had expected.

Rabbits have been a problem on Macquarie Island for a number of years, but have become most troublesome recently. As I mentioned in my previous post on pest species, rabbits are most dangerous in large numbers, especially to local vegetation.

The last estimate of the population size of rabbits on Macquarie Island was around 100,000 and in such large numbers, they can certainly mow through the vegetation. These mega-herbs are crucial for a number of invertebrate and sea-bird species that are, in many cases, endemic to the island. What’s more is that Macquarie Island has peat soil that is easily eroded without the support that these mega-herbs provide.

So how did they achieve it? Eradicating such a virulent species from an isolated island is no easy task. The snippet below from the ECOS Magazine article sums it up nicely, but I highly recommend having a look at the full article and doing a little dance for the mega-herbs of Macquarie Island.

“Three months before aerial baiting resumed in 2011, rabbit calicivirus was introduced to the island to reduce the rabbit population. This step was part of a risk management strategy to minimise the number of poisoned rabbit carcases above ground that could be eaten by predatory or scavenging seabirds.

By last July, the last of the poisoned bait had been dropped from helicopter-slung buckets. Teams of hunters, accompanied by highly trained sniffer dogs and handlers, then arrived on the island to ‘mop up’ remaining pests. While they initially managed to flush out 13 rabbits, none have been detected on the island since December.”

Problematic Predators: An Introduction to Pests in NZ

You may have noticed that I continue to mention these things called introduced mammalian predators or pests.  I realise that I haven’t yet informed my readers of what these pests actually are, and why they are so damaging to New Zealand’s natural environment.

The Sub-Antarctic Islands have not come out unscathed by introduced predators. To date, the Department of Conservation has carried out two separate eradication programmes on both Campbell and Auckland Islands – the latter of which, was a complete success. The only remaining pest species are pigs, cats, and mice on Auckland Island, and mice on Antipodes Islands (which will hopefully change in the near future).

This long overdue blog post is about five of the ferocious and frustrating pest species that plague New Zealand in general.

Please note that this blog post includes videos that may disturb and that these five pests are not the only predators plaguing New Zealand.

1. The Rat

We often hear about ‘rats’ being a pest, but did you know that there are actually three species of rat threatening New Zealand’s wildlife?

The kiore (or Pacific rat) was introduced by early Maori settlers in the 10th century and both the ship rat (black rat) and Norway rat were introduced by early European settlers in the 17th century.

All three species negatively impact the environment by eating rare weta, frogs, snails, tuatara, lizards, insects, birds, as well as the fruits, flowers, and seeds of native plants. Of all the species, the Norway rat is the largest, followed by the ship rat and both are known to prey on birds eggs,  chicks, and even in some cases – the adults. They’re very bad news for biodiversity.

2. The Rabbit

The rabbit was brought into New Zealand in the early 1830’s as a source of food and activity in the form of hunting. What early european settlers didn’t predict was how well these rabbits would do, and how busy future generations of farmers would be keeping plagues of them from destroying their pastures.

In New Zealand, there were many attempts to control the population that included introducing stoats, poison, digging out burrows, and even establishing a commercial industry exporting rabbit skins. While some of these methods have controlled rabbit populations, they are still widespread throughout New Zealand.

In the Southern Ocean, the rabbit is best known for eating out entire fields of mega-herbs on Macquarie Island, an Australian Sub-Antarctic Island. A number of attempts to eradicate them from the island have occurred over the past 5 – 10 years with the main challenge being the quick removal of carcasses that is required to prevent secondary poisoning of carrion eating species such as skuas.

3. The Stoat

Ironically, the stoat was introduced to New Zealand with the hopes that it would control the rabbit population. Although it is a natural predator-prey relationship in the northern hemisphere, it didn’t turn out so well in New Zealand as the stoats found other New Zealand wildlife easier to catch.

Stoats are most problematic following a beech mast, which involves a large number of beech trees in a forest releasing their seeds at the same time. Following these events, mice numbers increase drastically and in the years following a beech mast, stoat numbers soar as they are able to prey on mice. Once mice numbers have declined, however, the increased stoat population will prey on native birds and animals and can have incredibly negative effects on native population numbers.

4. The Mouse

On the mainland, mice are most often observed eating berries, seeds, and insects on the forest floor. Like the stoat, they are most abundant following a beech mast on the mainland of New Zealand. Luckily for the Sub-Antarctic Islands, there are no beech trees to fuel such plagues. But that doesn’t mean they are not a threat to species in the Sub-Antarctic.

On islands, mice are recorded to act more like rats, and will take larger prey, including bird eggs, chicks, and even adults. A recent video shows a group of mice literally eating an albatross chick alive in the nest, a time when it is most vulnerable to predation.

 

Once again, I have to mention the Million Dollar Mouse project that Gareth Morgan is currently running, which aims to raise enough funds to eradicate mice from the islands. I keep pushing this project because I believe in it, and it’s a great way to raise awareness for Aotearoa’s Sub-Antarctic Islands.

5. The Cat

I think people tend to forget that their pussy-cats are the perfect predators. Cats often hunt out of instinct, and wont always eat their kill. They’re more likely to kill for a challenge, rather than to survive.

One example of the damage that cats can have is seen in the story of the Steven’s Island Wren. The most common story is that the lighthouse keepers cat, named Mr. Tibbles, was responsible for the species’ extinction. Although possible, it is more likely that the species became extinct as a result of predation by feral cats in the winter of 1895, just 14 years after humans first settled on the island in 1881.

While the best way to control cats is to treat them like every other pest, it’s only natural for humans to keep pets and we tend to believe that cats are the perfect companion. There are a few things you can do to control your pussy-cat, however, that will benefit both your conscience and the natives around you:

Keep your cats inside at night, have them wear a bell if they are outside at any time, have your cat de-sexed to prevent them breeding with feral cats, never abandon a cat, and of course the most obvious – try to keep your cat well fed and watered so that it’s never required to hunt to survive.

Incredible Endemic Species of the Southern Ocean.

If you thought that New Zealand’s mainland has some pretty special animals, wait until you meet the incredible endemics that you’ll find living on the Sub-Antarctic Islands.

What does endemic mean, I hear you wonder. It means that an animal is found nowhere else in the world. The perfect example is the kiwi on New Zealand’s mainland. The pukeko, on the other hand is a native because it’s also found across the ditch in Australia, where they call it the purple swamp hen.

So what endemic species call the Sub-Antarctic Islands home? Let’s meet three of the regions incredible endemics…

1. The Snares Penguin

The Snares Penguin (Photo: Wikimedia)

How do you fit 50,000 penguins on an area of just 3.5 square kilometres? Head down to The Snares Islands and find out. The Snares penguin are found nowhere else in the world, and have very little space to work with.

If they look familiar, it’s because they’re related to the crested penguins that we know and love like the Fiordland crested penguin and the rockhopper penguin.

While the Snares penguin is not considered as threatened, it is vulnerable to extinction because of its limited range. If a threat to its survival were to arise, it would quickly wipe out a large proportion of the population and because they are found nowhere else on the planet, recovery would be slowed down significantly.

2. The Antipodes Island Parakeet

The Antipodes Island Parakeet (Photo: ExplorNZ)

The Antipodes Island Parakeet is the largest in it’s genus and is closely related to the yellow, orange, and red-fronted parakeet (you may know them as kakariki) that are found throughout New Zealand.

As it name would suggest, it’s only found on the Antipodes Islands, a small rock in the middle of the Southern Ocean. Its main island is a mere 20 square kilometres in size, and is surrounded by a number of rocky islands and outcrops no more than 2 square kilometres in size.

The greatest threat to these birds is the introduced mouse population on the Antipodes Islands, which I mentioned in a previous blog post. They predate on the eggs and adults of these birds, and can only be stopped through eradication. Take a look at the Our Far South Million Dollar Mouse Project.

3. The Royal Penguin

Royal Penguin on Macquarie Island (Photo: Kimberley Collins)

The royal penguin is found on an island that I haven’t yet covered on this blog, despite it being an interesting and important island habitat for species in the Southern Ocean. Macquarie Island is an Australian Territory found about halfway between the Australian mainland and Antarctic.

The royal penguin is endemic to the island, and a number of colonies are scattered throughout the island, the largest consisting of around 30,000 breeding pairs. Like the Snares penguin, it’s a member of the crested penguins genus (Eudyptes).

The Tasmanian government issued a hunting license for the royal penguin between 1870 and 1919 and an average of 150,000 penguins were killed each year for their oil, with each penguins providing around half a litre. Despite this dark period in their history, the royal penguin are not considered threatened and remain in large numbers on the island.

Sailing the Sub-Antarctics

Once upon a time I somehow convinced the good people at Heritage Expeditions to let me travel on their ship, the Spirit of Enderby. We were bound for the Sub-Antarctic Islands, a region so wild that only the bravest of souls have endured the arduous journey to their shores.

I could have done the typical “kiwi O.E.” and gone to the homeland to yell at the Queen from the street outside Buckingham Palace, or joined the London haka on Waitangi Day. But no, I chose to spend 26 days island hopping in the Southern Ocean, one of the most wild and isolated environments in the world.

There’s something a little more satisfying about doing a one-person haka for a colony of 60,000 penguins. I can’t say exactly what it is, but the look of appreciation on their little black and white faces is like no other I have seen in my life. They’re great listeners, penguins. And they don’t mind my socially awkward remarks or the fact that I will tell my life story to anything with a face (inanimate objects included).

My audience of 60,000 Royal Penguins on Macquarie Island. (Photo: Kimberley Collins)

The hardest crowd to please is definitely the pinnipeds. While the fur seals are fairly relaxed and much like the stoners of the seal world, the New Zealand sea lions I met were a whole other kettle of fish. They’re like grumpy old men. Make a noise louder than a whisper and they’ll bang on the wall and should flibber-jabber remarks that only someone who was born in the 1800’s could understand. And by that I mean they will challenge you.

When a New Zealand sea lion challenges you, you’re not supposed to run. The idea is to appear bigger than him. A stick can come in handy, and I was told by a researcher on Campbell Island to stand still, be tall, and hold a stick high above my head. If that doesn’t work, the general idea is to kick the sea lion in the face and run away, although I don’t think many have resorted to that method just yet. Most scientists would rather get bitten than live with the knowledge that they kicked an endangered species in the face.

The hunk of burning love that challenged me on Enderby Island. (Photo: Kimberley Collins)

So you can see why I am slightly neurotic about the region. There are stories to be told and adventures to be had and that’s why I have chosen to blog about the Sub-Antarctic Islands. Not to convince you that they are a valuable and irreplaceable ecosystem that deserve every New Zealanders undying attention (you should have received that memo at birth), but to tell you the stories that make the Sub-Antarctic stand out from the crowd and unlike any environment in the world. Bear with me, there are only so many adjectives that one can use to describe this region.