A Deep Dive into Modern New Zealand Extinctions Part 2

We recently explored three modern New Zealand extinctions.

In each instance, we identified a major contributing factor to extinction. Worryingly, each identified factor is presently manifesting in the plight of another critically endangered species. This suggests we are not learning from our mistakes.

Extinction isn’t a thing of the past—we are in the midst of a planet-wide extinction event. New Zealand is not immune to this devastation; more than twenty of our endemic birds are critically at risk of vanishing within thirty years.

If we do not take action, the magnitude of this extinction event could eclipse any other period in human history. Given this immediate risk, we must ask ourselves: what else can we learn from the past? And how might it inform how we approach these issues today?

With that in mind, let’s investigate another three modern extinctions and see what we can discover.

The Bush Wren was officially lost in 1972

The Tragic Tale of the Bush Wren

The Bush Wren is a member of a large family known as Acanthisittidae, small passerines that formed six distinct species and numerous subspecies. Of this vast family, only the Rock Wren and their distant cousin, the Rifleman, remain.

Bush Wrens were unable to survive in the presence of rats. The Bush Wren was extremely small, weighing just a few grams. They tended to live close to the ground, in dense native vegetation, feeding on grubs and insects. It has been suggested that they filled the ecological niche of mice and shrews, which seems to account for their downfall.

Unlike other birds, stoats were probably not the primary cause of their loss, though they were certainly a contributing factor. Norwegian Rats and Ship Rats appear to have been the architects of their demise. We can infer this because the Bush Wren thrived across New Zealand, even in the presence of the Polynesian Rat, suggesting that it was simply not large enough to pose a significant threat to the wren population.

Similarly, Bush Wrens disappeared from areas entirely absent of stoats, such as Stewart Island. They appear to have wilted in the face of rat invasion. In the North Island, they vanished by around 1910, though limited numbers survived in Te Urewera National Park until the 1950s. In the South, the final Stewart Island sighting took place in 1951.

High-altitude bush areas appear to have been their last refuge. Typically, these locations were immediately adjacent to the habitat of their cousin, the Rock Wren. The Rock Wren survives today, relatively unmolested, partly due to the isolation of the mountains it inhabits and the reluctance of rats to venture into the alpine zone. The last South Island reports came from these high-altitude environments. Bush Wrens were observed in Milford Sound until 1965, in Arthur’s Pass several times from 1966 to 1968, and in Nelson Lakes National Park in 1968.

On Big South Cape, an isolated island off the coast of Stewart Island, they survived until a rat invasion in 1964. Wildlife officers translocated half the birds to the nearby Kaimohu Island. Tragically, they never settled; two final birds were sighted in 1972, both of whom died that same year without producing offspring.

Challenges in Confirming Extinctions

A common theme presents itself among the animals we've explored. It seems very likely that they survived for a while longer elsewhere. It’s worth noting that, much like the South Island Brown Teal, the Bush Wren did not attract attention. It is difficult to distinguish from its cousin, the Rock Wren, especially given their overlapping habitats.

Extinctions in New Zealand tend to follow a set pattern. Species tend to disappear across the North Island, the eastern South Island, the West Coast, and then finally Nelson before hanging on in Fiordland for a while longer. That the Bush Wren was not observed adhering to this pattern suggests an inability to distinguish it from the Rock Wren and a general lack of public awareness. Only those familiar with the wren family would have been qualified to differentiate between the Bush Wren and the Rock Wren.

Moreover, they are not a species that attracts national interest. Few people even know what a wren is, let alone have the ability to positively identify one. We have credible reports of Bush Wrens from both Nelson Lakes and Kahurangi National Park until the 1990s.

Given this, it is entirely conceivable that the Bush Wren survived in Fiordland into the modern era. By way of comparison, the last positively identified Kakapo in Nelson was seen before the last Bush Wren, while the last generally accepted physical sighting of a Fiordland Kakapo was in 2004 (with probable Kakapo calls recorded through to 2012).

The Bush Wren was probably a victim of its evolutionary success. In a world free from ground-dwelling predators, they adapted to living on forest floors, where they thrived until rats encroached on their habitat. It is fascinating that they seemed to have been doomed by this trait alone.

The Rifleman, a cousin of the Bush Wren, remains common across New Zealand today simply because it nests and feeds higher off the ground. However, it is important to remember that the true death knell for the Bush Wren was ultimately due to a lack of knowledge and interest in the species. It seems entirely plausible that had there been greater interest in the species in the early 1960s, we would still have them with us today.

The Bush Wren could have been saved.

The Loss of our Greater Short Tailed Lost Bats

It’s difficult to prevent the extinction of a species you don’t even perceive to exist. The Greater Short-Tailed Bat was so poorly studied that it wasn’t declared a distinct species from the Lesser Short-Tailed Bat until after it had vanished.

Greater short-tailed bats were not understood to be a unique species until after their extinction. Bats in New Zealand are not well understood. They’re not exactly a poster child for our wildlife. In contrast to the Kakapo or Kiwi, bats are perceived to be ugly, scary, and unpleasant.

It’s not helped by the fact that they are rarely seen due to their nocturnal nature and often carry disease. Even bat colonies close to major urban areas in Otago and Canterbury have only recently begun to receive attention. In part, this is due to the unglamorous, expensive, and time-consuming nature of the work. Given these factors, the Greater Short-Tailed Bat was simply never on any conservation agenda.

Historically, we believe the species to have been widespread across New Zealand. Though identification is difficult, most authors don’t specify what type of bat they observed, and few specimens were collected. If the Greater Short-Tailed Bat was present on the mainland into the modern era, it certainly was not recorded. Nor do we have a precise record of their decline. We can only say with certainty that they survived on islands free of invasive species, notably off the coast of Stewart Island.

No known quality images exist of the greater short tailed bat

The Untold Story of New Zealand's Lost Bats

Even these colonies declined when pests invaded. It's a similar story to the Bush Wren. By the 1960s, Big South Cape was home to the last Greater Short-Tailed Bats. It’s now believed that in late 1963, rats arrived on the island, likely on the boats of Mutton-bird hunters who frequented the island. The following season, the Mutton-birders returned to find ecological devastation. Rats had overrun the locality, and birdlife was much diminished.

Local wildlife officers stepped in to assist with the recovery of the birds, but no one had any idea how to save the bats. The last accepted sighting was in 1967, after which the species was never positively identified again. Big South Cape off the coast of Stewart Island.

Was it the end? It seems unlikely. Big South Cape is the largest island in an archipelago. Bats are capable of flight; it’s possible they were present on other nearby islands, many of which were unmolested by rats. It’s helpful to appreciate that nearby Codfish Island is of similar size. Despite year-round human presence, individual Kakapo have remained hidden on the island for periods in excess of twenty years.

Sound detectors on nearby Putahuhina Island picked up bat-like calls in 1999. Numerous bat sightings have also been reported to the Department of Conservation from the same area. Considering it’s just a kilometre away from Big South Cape, there’s every likelihood a remnant bat population was present on the island.

Reports eventually became so compelling that a search was undertaken in 2009. No evidence was found of a colony; however, the search was hampered by poor weather. Unfortunately, no further reports have been received, suggesting that we have finally lost the Greater Short-Tailed Bat.

Tragically, at the time it was needed, there was no interest in bats. It’s hard to start a programme to conserve a species you’re not even studying. It’s not just that their plight was poorly broadcast to the public; it was completely unknown. You simply cannot save an animal you don’t know needs your assistance.

Bats are not easy to find funding for

South Island Kōkako: An Uncertain Survival Story

I agonised over including the South Island Kōkako in this article, simply because there’s not sufficient evidence to suggest they’re completely extinct.

Ultimately, though, it was this factor that convinced me to include them. Both their elusive nature and uncertain conservation status are precisely why we need to address them alongside animals we are confident have become extinct.

The South Island Kōkako is a grey and blue wattlebird, the cousin of the North Island Kōkako, and part of an extended family that includes the saddleback and huia. Well known to early Europeans, it was often referred to as both the 'Orange Wattled Crow' and the 'Grey Ghost of the Forest.' Its haunting melody and elusive habits were hallmarks of its nature even when widespread.

A significant difference between North and South Island Kōkako involves their feeding and nesting habits. South Island Kōkako nested and fed closer to the ground. This brought them into direct conflict with stoats, who found them easy to prey upon. Females of both species are vulnerable while they nest; consequently, populations seem to have rapidly become male-dominated.

Kōkako were rare everywhere by the 1930s. In a notable departure from other apathetic conservation efforts, there was considerable public outcry to save the Kōkako. Many well-known commentators called for their translocation to offshore islands. Unfortunately, public interest did not translate into action. No government department was directly responsible for the conservation of wattlebirds. Everyone seemed to believe it was someone else's job.

Tragically, this culminated in the Kōkako last being sighted on Mount Aspiring in 1967. The sharp-eyed among us may observe that this is a departure from the pattern of extinction we explored for the Bush Wren. This is, in part, due to the complicated nature of what it takes for a sighting to be accepted as genuine. This stumbling block has caused more headaches for those searching for the Kōkako than any other problem.

The South Island Kokako is listed as 'Data deficient'

Developments in Kōkako Conservation

The official position of the Department of Conservation is that the Kōkako is extinct. Is it, though? The evidence seems to suggest otherwise. Since 1967, more than three hundred sightings have been logged. By way of comparison, the Kakapo is universally accepted as having been present in Fiordland until at least 1989/90. However, between 1967 and the present day, fewer than forty Kakapo sightings have been logged. That’s almost ten times fewer than the Kōkako!

Additionally, despite not meeting the same criteria applied to the Kōkako, four Fiordland Kakapo reports were determined by the Department of Conservation to be genuine and followed up. What, then, is the standard used to determine if a sighting will be accepted as genuine?

It’s an almost impossible standard to achieve. To some degree, that’s by design, too. Audio recordings won’t meet the mark, primarily because none were ever made of the South Island Kōkako. Nor would an individual sighting. There’s no guarantee a group sighting would be accepted, either. These days, a clear photo might not even be accepted, due to the difficulties with photo manipulation. You’d probably need multiple photos or a video to prove beyond reasonable doubt that the Grey Ghost of the Forest still exists.

The existence of the South Island Kokako is debated

Recent Updates in the South Island Kōkako Saga

Further complicating things, there is considerable disagreement within the scientific community as to the exact standards that should be applied to determine if a species has been rediscovered. For instance, a 2007 Kōkako report was rejected by the Department of Conservation, despite multiple reliable observers, intimately familiar with the Kōkako, viewing a bird for an extended period of time. Within a year, the Department of Conservation would proceed to declare the Kōkako extinct, despite being fully aware of the report.

The same report would then go on to be accepted by the New Zealand Ornithological Society in 2013. This caused considerable embarrassment for the Government, who were forced to reclassify the bird as 'data deficient.' Recently, the official position of the Department of Conservation has become, 'show us proof that the Kōkako continues to exist, and we will fund efforts to save it.'

Critics bemoan that this is essentially a self-fulfilling prophecy, designed to ensure the government is not responsible for the fate of the Kōkako. Implicitly, the government probably would agree with this assessment, though you’d struggle to find a politician or civil servant brave enough to admit it.

This is in part due to the high costs associated with saving the South Island Kōkako. Any remaining populations are likely to be almost exclusively male-dominated. Moreover, they're probably fragmented over hundreds of kilometres of inhospitable terrain. The cost to find, study, and translocate any remaining birds would be tens, if not hundreds, of millions of dollars. The funding simply does not exist to achieve this.

There is also no guarantee any operation would be successful. The Kōkako was called the Grey Ghost of the forest for a reason. Even when widespread, it was notoriously hard to find. I'm unaware of any photographs that exist of birds in the wild. The bar for accepted evidence seems impossible to meet, and until now, the public has not been engaged on a level whereby they would push for rediscovery.

Despite all this, some weeks ago, a compelling audio recording from the Heaphy Track was made. It has since been submitted to the NZ Ornithological Society for consideration. It has attracted considerable attention and gone viral globally. Speaking to those involved, they’ve actually had a spate of reports across a single location on the track, which has led to a compelling body of evidence suggesting at least one bird remains.

Another chapter of the story of the South Island Kōkako may yet be written.

The final Chapter on the South Island Kokako may not yet be written

National Restoration: A Billion-Dollar Challenge

Conservation is hard work. Funding is hard to come by, particularly for species that don’t grab the public's attention. Bats are hard to make interesting, Bush Wrens are unremarkable, and Kōkako are too elusive.

We tend to underestimate what it costs to save a species.

Our flagship species, the Kakapo, requires millions of dollars and tens of thousands of man-hours annually to save. They’re actually less intensive than other species, too, given they’re centrally located across a few offshore islands, with few immediate threats.

We have in excess of four hundred bird species that require urgent attention now. In addition, we have hundreds of at-risk lizard, skink, and gecko species, the health of our forests and streams, pest control, marine life, and ongoing research to consider.

For New Zealand to effectively tackle national restoration on a meaningful level, we would need to run up a budget of billions of dollars. Not for a second would I advocate abandoning this vision.

Quite the opposite. We must, as a nation, climb this mountain however high it might be. But like any mountaineer would admit, being prepared is half the battle. We must appreciate the magnitude of the task at hand and apply what we’ve learned from the species we’ve lost.

If we can achieve that, we might just make a difference.

It's a tough journey to save our native species. 

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