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.

The Toughest Little Duck in the World.

Campbell Island is home to the toughest little flightless duck in the world. The Campbell Island teal has fought to survive in its cold and windy island environment. It’s the rarest duck in the world and there was a time when we thought it to be extinct altogether.

The Campbell Island teal is one of just a few species of duck that is flightless and semi-nocturnal. It evolved these features because it had no land-based predators to compete with and why waste energy flying when you don’t need to.

The Campbell Island teal (Photo: WIkimedia)

The toughest little duck in the world didn’t cope well to the introduction of Norway rats from sealing and whaling ships in the early 1800’s. By the time naturalists arrived on the island in 1840, there wasn’t a land bird in sight.

After several supposed sightings but no live specimens, hope began to fade and it was assumed that the Campbell Island teal was extinct. However, in 1975, visiting conservationists Christopher Robertson and Rodney Russ could hardly believe their eyes when they pulled a female Campbell Island teal from behind a moving tussock on Dent Island.

Dent Island, the last remaining strong-hold of the Campbell Island Teal (Photo: DOC)

The Department of Conservation moved quickly to remove some of the birds to a predator-free sanctuary in Pukaha Mount Bruce. They took 3 males and 1 female and attempted the first ever Campbell Island teal captive breeding programme.

Initially, the breeding programme failed and so they returned to Dent Island in 1984 where they captured another 4 males and 3 females. In 1994, the world was over-joyed to see the first captive-raised ducklings and hope was quickly restored in the conservation of the Campbell Island teal.

Campbell Island Teal (Photo: Bill Morris)

In 2000, the captive breeding population had gone from 11 adult birds to a total of 60 birds. A number of these birds were quickly re-located to Codfish Island (Whenua Hou) off the coast of Stewart Island to act as a “back-up population” in case disease threatened the group.

The Codfish Island population didn’t last long, and 50 birds were re-located back to Campbell Island in 2004 after rats were eradicated in 2001. Another 55 were released in 2005, and 54 in 2006, which boosted to total estimated wild population number to 159.

Perseverance Harbour, Campbell Island (Photo: Kimberley Collins)

The eradication of rats from Campbell Island saw vegetation, wildlife, and invertebrates flourish and in 2006, the first island-born ducklings were observed on the island. Conservationists finally had the evidence they needed to see that all their hard work had paid off in saving a tough little flightless duck from extinction.

This inspiring story is one of many on Campbell Island, stay tuned to find out more about the ambitious rat eradication programme and the return of the Campbell Island snipe…

Dangerous Discoveries: Charting the Sub-Antarctics

Modern ships struggle in the rough seas of the Southern Ocean, but imagine how difficult it would be to explore the region for the first time without any maps or the luxuries of a modern ship.

The wooden ships used by early explorers were no match for the rough seas and harsh rocks surrounding the Sub-Antarctic Islands, but those that were successful in charting new islands often came away with a name-sake and a fortune from harvesting seals and whales for their skin, meat, and oil.

Let’s take a look at New Zealand’s Sub-Antarctic Islands and find out how and when they were charted and the stories behind their discovery.

The Auckland Islands

The Auckland Islands were officially discovered by a whaling vessel named Ocean in 1806, although archaeologists have uncovered evidence to suggest that were settled by Polynesian explorers around the 13th century, which makes the islands the most southerly settlement by Polynesians known.

The Auckland Islands (Photo: Kimberley Collins)

Upon their re-discovery, Captain Abraham Bristow named the main island “Lord Auckland’s” in honour of the first Baron of Auckland, William Eden. He also named Enderby Island after his employer, Samuel Enderby, who ran a successful whaling company from the United Kingdom. It wasn’t until 1807 when Captain Bristow returned to the islands that they were officially claimed for Britain.

The Antipodes Islands

Similarly, the Antipodes Islands were visited early on by Polynesian explorers. Visitors to the island in 1886 discovered a shard of what they believed to be early Polynesian pottery, which is now kept in the Museum of New Zealand (Te Papa Tongarewa) in Wellington.

The Antipodes Islands as seen from the north (Photo: Wikipedia)

The Antipodes Islands were re-discovered in 1800 when Captain Henry Waterhouse of the ship HMS Reliance charted the region. Captain Waterhouse’s brother-in-law, George Bass heard about the regions rich wildlife and applied to have monopoly of fishing in the region. After securing permission to fish in the region, he set off immediately for the islands, presumably to begin harvesting the large population of fur seals. He was never heard from again, but his eagerness to get to the islands sparked interest in other businessmen and lead to the sealing boom from 1805 until around 1807.

The Bounty Islands

The HMS Bounty was the first ship to discover the Bounty Islands in 1788 with Captain William Bligh at its helm. While the discovery itself was uneventful, the famous mutiny that occurred on-board shortly after the islands were discovered was not.

The HMS Bounty (Photo: Wikipedia)

On the 28th of April 1789, the ship was moored off the coast of Pitcairn Island near Tahiti. It is said that many of the crew were tired of being treated harshly by their commander, Lieutenant Bligh, and wanted to take up residence on the nearby Tahitian Islands. They soon revolted and set Bligh and 18 of his most loyal crew members afloat in a small boat before settling on Pitcairn Island. Eventually, after an epic journey, Bligh made it to  Timor in the Dutch East Indies before returning to England and reporting the mutiny. Many descendants of the sailors that rebelled are still found on Pitcairn Island.

The Snares Islands

The largest of the Snares Islands were known to the Maori as Te Taniwha (which translates to “the sea monster”), but they were officially discovered by two ships working with the same expedition on the same day, but only one captain was allowed the honour of naming them.

The Snares Islands (Photo: Kimberley Collins)

Captain George Vancouver of the The HMS Discovery called the islands “The Snares” because of their ability to trap wayward ships with little experience in the area.  The second ship was the HMS Chatham, and while its commander Lieutenant William Broughton didn’t get to name the islands, one was named Broughton in his honour.

Campbell Island

Campbell Island gets its name from Robert Campbell,  the owner of a Sydney based trading company by the name of Campbell & Co. It was discovered in 1810 by the Perserverance, which was scouting the area for new sealing grounds. Its commander, Captain Frederick Hasselborough also discovered the Australian Sub-Antarctic Island, Macquarie Island.

Ironically, Captain Hasselborough drowned in Perseverance Harbour when he launched a jollyboat to check on the barrels of seal oil that he had left on the shore during his first visit.

Campbell Island (Photo: Kimberley Collins)

Penguin Cam on South Georgia Islands

Today I am going out of my comfort zone to report on a recent project in the South Georgia Islands. If you have ever wanted to spend the day in the life of a penguin, you may have already seen this research done by the Zoological Society of London on Sub-Antarctic South Georgia Island.

They placed a number of cameras around the Sub-Antarctic region and in Antarctica with hopes to gain an insight into the breeding cycle of penguins that would usually not be seen by humans. The lower latitudes experience extreme weather patterns  and during harsh winter months, it is often impossible for scientists to stay on the islands to conduct research.

The location of South Georgia.

South Georgia is a British overseas territory best known for being one of the locations of the Falklands War. Captain James Cook was the first to land on the island in 1775 and claimed it in the name of the British Empire, despite it having been discovered on numerous occasions prior to his visit.

A king penguin on Macquarie Island (Photo: Kimberley Collins)

Despite its interesting history, it remains a haven for wildlife and the perfect location for researchers to study its main inhabitants, the king penguins. Cameras on South Georgia Island were weighed down with rocks over-looking king penguin colonies. They took several photos a day, and compiled them to make a time-lapse of a typical winter on the islands.

Penguin lover or not, a recent discovery of new emperor penguin colonies in Antarctica made headlines and are another example of how technology can improve our ability to collect data on species in remote areas.

The Yellow-Eyed Penguin

This week was world penguin day and to celebrate, I thought what better to write about than New Zealand’s own yellow-eyed penguin or hoiho.

New Zealand's five dollar note showing the hoiho. (Photo: Yellow-Eye Penguin Trust)

You may recognise these guys from the reverse side of the New Zealand five dollar note, but did you know that the hoiho was once the rarest species of penguin in the world? While the title is now taken by the Galapagos penguin, there’s still cause for concern when it comes to conserving the yellow-eyed penguin.

It is estimated that there are just 4000 remaining, 1200 of which are found in the Sub-Antarctic Islands – specifically Campbell Island and the Auckland Islands. On the mainland, they are confined to the south-eastern coast of New Zealand and Stewart Island.

Image

Yellow-Eyed Penguins (Photo: © Steve Ting Photography 2012)

They’re by far the most skittish species of penguin I have met and on the odd occasion that you do see one, it will be waddling clumsily to the nearest patch of vegetation in order to hide from people, predators, and even other penguins.

Their lack of agility on land has caused population numbers to decline drastically since the introduction of mammals to Aotearoa. While they are adapted to avoiding predators in the ocean while foraging for squid and fish, they are unable to defend themselves from predators such as cats, rats, stoats, and dogs.

Farming and the removal of vegetation along coast-lines has further threatened this species, as it significantly reduces sheltered spots that penguins would usually use for safe and successful nesting spots when breeding.

Yellow-Eyed Penguins and their chick (Photo: Wikimedia Commons)

Humans love penguins, and a number of organisations have an active role in conserving the species with the intention of bringing the hoiho back from the brink of extinction. The Yellow-Eyed Penguin Trust actively restores penguin habitat, controls pest numbers around known breeding areas, educates the public, and has an active hand in scientific research.

I would highly recommend taking a look at their website to find out how you can get involved in the conservation of this highly threatened species. They have a range of options for anyone who wants to help out including working at coastal restoration days, volunteering as a ranger, helping with administration, or donating to the project.

So the next time you are holding a five dollar note, turn it over and spare a thought for the plight of this plucky penguin!

A War on the Southern Ocean – The Cape Expedition

After ANZAC day this week, I got thinking about some of the military operations that happened in the Southern Ocean. From 1940 to 1945, a team of men lived on Campbell Island in order to guard the area from German ships and provide ample warning to the mainland of an attack from the south.

The story of how these men came to find themselves on the island began with a single ship leaving the port of Dunedin in August of 1939 with a supposed course for Australia. The 6000 tonne German ship, Erlangen, was rumoured to be using the Sub-Antarctic Islands as a base, removing large quantities of timber for fuel and remaining near the islands, ready to attack New Zealand should the orders come. In 1940 two ships were lost to German raiders, which fueled the rumours and resulted in the creation of a coast-watching team.

The Erlangen being "scuttled" (deliberately left to sink) later in its life. (Photo: PST!)

The coast-watchers, who operated under the code name of “the Cape Expedition” discovered that a large patch of forest had been removed in Carnley Harbour on the Auckland Islands, and so the New Zealand government set up three bases; on Campbell Island, Auckland Islands them up on Campbell Island to guard it from any further attempts by German ships to pilfer the area for resources and alert the mainland of any attempted attacks from the south.

Each team began with four men, but were increased to five in the second year (1941). Many began their coast-watching careers as civilians, but were made privates in the New Zealand Army from 1942 onwards. When they weren’t watching the sea for ships, they researched weather patterns, observed wildlife, and did small surveys. In their spare time, they hunted introduced mammal species such as wild pigs on Auckland Island, sheep on Campbell Island, and cattle on Enderby Island

Remains of the coast-watchers hut. (Photo: Te Papa)

Eventually, the New Zealand government found their data so regular and useful that they began to deliberately place men with an interest in natural history on the islands. These individuals included geologists, meteorologists, surveyors, and naturalists joined the party. While the positions were filled by different men each year, some remained longer by choice such as the naturalist J. Sorenson who remained on Campbell Island for four years.

Once the war ended in 1956, the coast-watchers station was abandoned and used for meteorological research on weather patterns in the area. A large proportion of the information gathered by coast-watchers was later released in the Department of Scientific and Industrial Research Cape Expedition series of bulletins.