Feral (wild) cats – and domestic cats on the prowl at night – have a devastating effect on native wildlife, which has not evolved to coexist with an efficient predator like the cat.
In April 2017, Margaret Christian of the Society prepared an brief explanatory memorandum which eventually accompanied a questionnaire for the people of the Island, conducted by the Norfolk Island Regional Council. The survey form presented three options:
Option 1 – Do nothing
Option 2 – Ban cats from Norfolk Island
Option 3 – Allow continued cat ownership under controlled conditions.
The survey revealed that 12% of respondents wanted cats banned completely and another ~68% wanted cats to be controlled. There was a vocal campaign by the cat lovers to be engaged in the survey. They took out half page advertisements in the paper, but the results showed that they were in a minority.
Unfortunately, the changes in governance came soon after and there has not been much progress towards establishing a Pound, one of the highest priority proposals that came out of the survey. However, the present Island-wide cat monitoring and some feral cat control has been funded by the Australian Government, using the survey results as evidence of the community’s attitude supportive of control.
Before ceasing, the Cat Welfare and Wildlife Protection Association of Norfolk Island transferred a significant quantum of its residual funds to the Society to ensure that any cats trapped would be treated humanely.
On Phillip Island, off Norfolk Island’s south side, the population of Phillip Island Centipedes (Cormocephalus coynei) can kill and eat up to 3,700 seabird chicks each year. Luke Halpin and colleagues tell the story in an article in The Conversation on 3 August 2021.
Giant bird-eating centipedes exist — and they’re surprisingly important for their ecosystem
Giant bird-eating centipedes may sound like something out of a science-fiction film — but they’re not. On tiny Phillip Island, part of the South Pacific’s Norfolk Island group, the Phillip Island centipede (Cormocephalus coynei) population can kill and eat up to 3,700 seabird chicks each year. And this is entirely natural. This unique creature endemic to Phillip Island has a diet consisting of an unusually large proportion of vertebrate animals including seabird chicks.
Phillip Island in the Norfolk Island group, with a valley of iconic Norfolk Island Pine trees. Luke Halpin
As large marine predators, seabirds usually sit at the top of the food chain. But our new study, published in The American Naturalist, demonstrates this isn’t always the case. We show how large, predatory arthropods can play an important role in the food webs of island ecosystems. And the Phillip Island centipede achieves this through its highly varied diet.
A well-armed predator stirs in the night
This centipede can grow to almost one foot (or 30.5cm) in length. It is armed with a potent venom encased in two pincer-like appendages called “forcipules”, which it uses to immobilise its prey. Its body is protected by shield-like armoured plates that line each of the many segments that make up its length. On warm and humid nights, these strictly nocturnal arthropods hunt through thick leaf litter, navigating a labyrinth of seabird burrows peppered across the forest floor. A centipede on the prowl will use its two ultra-sensitive antennae to navigate as it seeks prey.
The centipede hunts an unexpectedly varied range of quarry, from crickets to seabird chicks, geckos and skinks. It even hunts fish — dropped by seabirds called black noddies (Anous minuta) that make their nests in the trees above.
A frightful discovery
Soon after we began our research on the ecology of Phillip Island’s burrowing seabirds, we discovered chicks of black-winged petrels (Pterodroma nigripennis) were falling prey to the Phillip Island centipede. We knew this needed further investigation, so we set out to unravel the mystery of this large arthropod’s dietary habits.
Black-winged petrel chick just prior to being weighed on Phillip Island. Trudy Chatwin
To find out what these centipedes were eating, we studied their feeding activities at night and recorded the prey species they were targeting. We also monitored petrel chicks in their burrow nests every few days, for months at a time. We eventually began to see consistent injury patterns among chicks that were killed. We even witnessed one centipede attacking and eating a chick. From the rates of predation we observed, we calculated that the Phillip Island centipede population can kill and eat between 2,109 and 3,724 petrel chicks each year. The black-winged petrels — of which there are up to 19,000 breeding pairs on the island — appear to be resilient to this level of predation.
Envenomation of a black-winged petrel nestling by a Phillip Island centipede. (Video by Daniel Terrington)
And the predation of black-winged petrels by Phillip Island centipedes is an entirely natural predator-prey relationship. By preying on vertebrates, the centipedes trap nutrients brought from the ocean by seabirds and distribute them around the island. In some sense, they’ve taken the place (or ecological niche) of predatory mammals, which are absent from the island.
Luke Halpin monitoring black-winged petrel chicks on Phillip Island. Trudy Chatwin
Restoration and recovery
Up until just a few decades ago the Phillip Island Centipede was very rare. In fact, it was only formally described as a species in 1984.
After an intensive search in 1980, only a few small individuals were found. The species’s rarity back then was most likely due to severely degraded habitats caused by pigs, goats and rabbits introduced by humans to the island. The removal of these invasive pests enabled black-winged petrels to colonise. Their population has since exploded and they’re now the most abundant of the 13 seabird species that breed on Phillip Island. They provide a high-quality food source for the Phillip Island centipede and have therefore likely helped centipede population to recover.
Black-winged petrels on Phillip Island are active both during the day and at night. (Video by Luke Halpin)
Ancient bone deposits in the soil suggest that prior to the black-winged petrel’s arrival, Phillip Island was home to large numbers of other small burrow-nesting seabird species. It’s likely the Phillip Island centipede preyed on these seabirds too. Now, thanks to the conservation efforts of Norfolk Island National Park, the island’s forest is regenerating alongside endemic species like the centipede, as well as the critically endangered Phillip Island hibiscus (Hibiscus insularis).
The endemic Phillip Island hibiscus. Luke Halpin
As a driver of nutrient transfer, the persistence of the Phillip Island centipede (and its healthy appetite) might just be key to the island’s ecosystem recovery. But we’ll need to do more research to fully understand the intricate links in this bustling food web.
Norfolk Island has an extremely healthy European bee population. The first European bees recorded on Norfolk Island were in the 1840s when the convict settlement was operational.
The Norfolk bees are free from European and American Foulbrood and we have no hive beetles or Varroa mite. The spores for European and American Foulbrood are able to survive in untreated honey and on bee equipment for at least 80 years. No importation of used bee equipment (which includes clothing and shoes) is allowed into Norfolk Island.
Unfortunately since 2016 (when Australia assumed control of Norfolk Island) 750g of untreated honey for personal use is allowed to be imported by anybody with the one proviso that it is “not to be fed to bees.”
To keep this bee population safe we requested that Norfolk Island become part of the Australian Sentinel Hive programme. As part of that programme we have set up sentinel hives at all the first points of entry on Norfolk Island. If there is an incursion of a pest or disease then these hives hopefully will be the first affected and that will give us a fighting chance to treat/eradicate any invader.
We monitor the sentinel hives on the first of each month and use different techniques to check for a variety of pests/diseases and this information is then immediately passed on to Plant Health Australia who collate all the information from all the sentinel hives scattered around first points of entry on mainland Australia.
We have put in a submission to the Commonwealth of Australia to have Norfolk Island declared a Bee Sanctuary but the response from the Commonwealth is that such a declaration is a State function and as Norfolk Island is a Territory not a State no sanctuary is possible.
A land snail listed more than 20 years ago as extinct was re-discovered in October 2020 by researchers from the Australian Museum. The Norfolk Island Flora and Fauna Society hosted a presentation on 22 October by Dr Isabel Hyman, supported by Dr Frank Köhler from the Museum and Brett Finlayson from Taronga Park Zoo. These investigators spent time during their visit surveying vegetation and plant debris in the parks and forests for these fascinating creatures. The ABC has the story.
The Society ran a bird survey across the island group in 2005, the first time since 1978 that the birds have been monitored methodically for their presence and distribution. Visiting volunteer bird watchers and professionals came to the Island from Australia, New Zealand, Canada and the United Kingdom to assist.
A provisional Bird List indicating extinct, endemic and native species has been compiled and is available free of charge.
In 1789 Philip Gidley King R.N. referred to the ‘destructive plagues’ of ‘parroquets’ which ruined the early settlers’ crops.
From this early record of abundance, the population declined to a low of fewer than 15 breeding pairs in the early 1980s. The Black Rat or Ship rat, Rattus rattus, believed to have been introduced during WWII, is a prime suspect. They were by then almost entirely restricted to the National Park, with only seasonal sorties outside the Park to raid their favourite of all the fruits, peaches.
At that time the (then) Australian National Parks & Wildlife Service launched a captive breeding program, and a parallel program of protecting the birds and their nest sites in the wild; the nest protection program proved to be the more successful strategy. Green Parrot numbers climbed to a possible 250 birds in the early 2000s, largely due to regular programs of cat control and rat baiting throughout the National Park, enhancing their chances of survival.
The importance of these activities was proven when, after the predator control measures eased (and for periods ceased) in the early 2010s, the Green Parrot numbers plummeted again to fewer than 20 breeding pairs. An urgent, concerted intervention by Parks Australia supported by local, Australian and international NGOs has produced excellent results, with over 400 birds now estimated, with pairs, individuals and groups being seen in all parts of the island.
Identification
Adult birds are a rich forest green, lighter green below, with a red crown, a red dot behind the eye, and a rich blue leading edge to the wing. The beak is light blue, gradually darkening towards the tip which is black. The eye is orange/red. Juveniles are similar to adults but their beak is pinkish and their eyes are brown. Sexes are alike, but the male is larger. Length 30cm.
