Lyall’s wren

The tragic story of Lyall’s wren

Like the dodo, Lyall’s wren is one of the best-known examples of the extinction of bird species, because the circumstances of its disappearance are as striking as they are tragic. The story of Lyall’s wren is often told with dramatic simplicity: a cat, brought by a lighthouse keeper to the previously uninhabited Stephens Island, is said to have discovered the world’s only flightless songbird, Lyall’s wren, and then wiped it out shortly thereafter.

In 1895, the Canterbury Press published an account of the incident, which is considered a classic example of the extinction of an island species—a species that had not developed natural defenses against newly introduced mammalian predators. The account stated:

“This is probably a record in the matter of extermination. The English scientific world will hear almost simultaneously of its discovery and its disappearance, before anything at all becomes known about its manner of life or its habits (…). And we are certainly of the opinion that the Marine Department, when it sends lighthouse keepers to isolated islands (…), should take care that they are not allowed to take cats, even if mousetraps have to be provided at the expense of the State.”

The Doomsday Book of Animals. 1981. p. 118. D. Day

Lyall’s wren – fact sheet

alternative names	Stephens Island wren, Stephens Island rock wren, Stephens Island rockwren, Steven Island wren, Lyalls wren
scientific names	Traversia lyalli, Xenicus lyalli, Xenicus lyalli lyalli, Xenicus insularis, Traversia insularis
original range	Stephens Island (New Zealand)
time of extinction	no later than 1899
causes of extinction	introduced animals on islands
IUCN status	extinct

Discovery and description of a new bird species

The story of Lyall’s wren began in April 1892, when workers arrived on the pristine Stephens Island to begin building a lighthouse that was to secure the western approaches to Cook Strait, along with the associated facilities. They encountered a great diversity of bird species; one of the workers, F. W. Ingram, described the island’s bird fauna:

“Saddlebacks, native thrushes, native crows, robins, two species of cuckoos, one with a long tail and one with a barred breast, also kākās, pigeons, New Zealand moreporks, two species of wrens [Lyall’s wren and South Island rifleman Acanthisitta chloris chloris] (very small birds), and I have also seen a land rail. There were hundreds of parakeets and tūīs (or tūī honeyeaters), also the moke moke (or Māori honeyeater)…”

Extinct Birds. 2017. p. 253. J. P. Hume

Up to that point, the island had hardly been visited and remained largely untouched. The scrub forest was still intact, and there were no introduced mammals. Stephens Island had probably remained free of human influence for millions of years; even if the Māori ever set foot on the island, they left no traces.

The lighthouse was completed in early 1894, and a crew of lighthouse keepers moved to the island with their families. In addition to sheep and cattle, at least one pregnant cat was also brought to the island in February of that year. A cat—possibly named Tibbles—began catching small birds in June 1894 and bringing them to the lighthouse keeper David Lyall.

Because Lyall was interested in ornithology and did not know this species, he kept the birds he caught and had them prepared as skins. When the supply ship Hinemoa called at the island, Lyall gave one of the skins to an engineer named A. W. Bethune, who took it to Wellington, where Walter Buller, New Zealand’s leading ornithologist, immediately recognized it as a new species and presented it at a meeting of the Wellington Philosophical Society in July 1894. Buller planned to publish a detailed description of the bird in the journal Ibis and had the specimen sent to London to have an illustration made.

News of the newly discovered bird species spread quickly, however, and Henry Travers, an experienced collector who had also received specimens from Lyall, saw an opportunity to sell them to the British ornithologist Walter Rothschild, who was known for acquiring rare species for his private museum. Travers sold a total of nine prepared skins of the bird that he had received from Lyall to Rothschild. Rothschild then published a hastily written description of the new species under the title Description of a New Genus and Species of Bird from New Zealand (1894) and gave the bird the name Traversia lyalli. In doing so, he preempted Buller, who had planned to describe the species under the name Xenicus insularis. For years, Rothschild and Buller argued over the discovery and naming of Lyall’s wren.

The bird’s scientific name, Traversia lyalli, honors the lighthouse keeper David Lyall, who first made the bird known to science. The genus was named after the naturalist and dealer in curiosities Henry H. Travers, who received numerous specimens from Lyall.

Was a single cat responsible for Lyall’s wren’s extinction?

Despite justified concerns about the negative impacts of feral cats (Felis catus) on ecosystems, much of what we think we know about the extinction of Lyall’s wren is wrong or misunderstood. The origin of this idea lies in an essay by Walter Rothschild from 1905, in which he claimed that a single cat had killed all specimens of Lyall’s wren on the small island of Stephens Island. In his book Extinct Birds (1907), Rothschild repeated this claim:

“All the specimens known to me, (…) were brought by the lighthouse-keeper’s cat. Evidently this feline discoverer was at the same time the exterminator of Traversa lyalli, and many of them may have been digested by this unique cat, for in letters which I received from Mr. Travers I was informed that no more specimens could be obtained (…).”

Extinct Birds. 1907. pp. 24f. W. Rothschild

The idea that a single cat was responsible for the species’ extinction became widespread in the years that followed. Rothschild’s source, Henry Travers, however, seemed to hold a different view. In his notes on Native Birds of New Zealand, probably written in the 1920s, Travers wrote:

“A cat [first] drew attention to the birds after it laid one at the door of a lighthouse keeper who was an enthusiast for native birds. The cats, however, soon made short work of the rest.”

Travers’ manuscript, MSY 3430, Royal Forest & Bird Protection Society Records, Alexander Turnbull Library, Wellington

Besides Travers, other early reports also mentioned “the cats” that had wiped out Lyall’s wren—not just a single cat. A description by Travers from 1898 also suggests that a larger cat population had colonized the island:

“I was on Stephens Island about four years ago and the (…) birds [piopio], saddlebacks of both species, robins and other birds were plentiful, especially the former, as they were there in hundreds. Now there are none of the former or latter and only very few of the others, all due to the fact that a cat, which was heavily pregnant, was taken from French Pass in a bag by its owner with the intention of throwing it overboard during the crossing. But when bad weather came up, the cat was forgotten until the island was reached, and in the hurry of landing the bag with the cat in it was taken ashore, and one of the men, without thinking much, cut the bag open and let the cat go. Now the island is swarming with cats.”

Travers to Hector, 27 December 1898, IA1 1898/251, Archives New Zealand, Wellington

It remains uncertain whether the pregnant cat was the only one brought to the island. It is also unclear whether it was the one that later laid birds at the lighthouse keeper’s door, or whether additional cats reached the island and developed into a large feral population.

By examining archival and museum records, the historian Ross A. Galbreath was able to refute the claim that Lyall’s wren’s extinction could be attributed to a single cat in The Tale of the Lighthouse-keeper’s Cat (2004). Cats likely arrived on the island from 1894 onward. They quickly became feral and multiplied rapidly.

A study from 2011 examined the impacts of feral cats on native island vertebrates and found that they are responsible for at least 14 percent of all global extinction events in birds, mammals, and reptiles. In addition, cats have significantly influenced the decline of at least eight percent of threatened species in these groups.

According to the authors of the study, cats have been introduced on about 179,000 islands worldwide. Since islands account for a disproportionate share of global terrestrial biodiversity, invasive cats can have drastic effects on species diversity there. Particularly affected are island species that have not developed defenses against these generalist predators—including many flightless bird species, which are threatened with extinction far more often than flying species.

The rapid growth of a cat population from 1894 onward on Stephens Island was probably the main factor in the extinction of Lyall’s wren, but it was likely not just a single cat that was responsible. In the early 1890s, when the island was still densely forested and free of introduced mammals, there were 25 different New Zealand landbird species there. With the arrival of the cats, other species disappeared in addition to Lyall’s wren, such as the now extinct Stephens Island piopio (Turnagra capensis minor).

When did Lyall’s wren really go extinct?

It is often reported that Lyall’s wren disappeared only one year after its discovery in 1894. Reports published in New Zealand newspapers in March 1895 also suspected that the bird had become extinct because of the cats brought to the island.

Historian Galbreath points out, however, that Buller’s and Travers’s records suggest that the extinction process lasted longer than is often assumed. After the first birds were collected in 1894, both Buller and Travers continued their efforts to obtain further specimens.

There is evidence that specimens of Lyall’s wren were still collected between 1896 and 1899. In a publication from 1905, Buller states that he owned three specimens of the bird in his collection and in his son’s collection, dated to 1899. Travers also reports in a letter to Rothschild from November 1895 that Lyall had not seen any further birds for some time and suspected that the species was extinct. At the same time, however, he mentions that he owned two specimens preserved in alcohol.

Although a cat apparently killed ten specimens in 1894, at least two to four specimens were collected in the following years in 1895 and possibly more up to 1899. These reports suggest that the population did not collapse immediately after its discovery, but declined gradually over several years. The sale of a specimen to the Otago Museum by Travers in 1898 also suggests that birds were collected after 1895.

Buller’s and Travers’s records therefore suggest that Lyall’s wren did not go extinct immediately after its discovery in 1894. Instead, the population seems to have declined over several years before the species finally died out around 1899.

Other causes of extinction: were cats solely to blame?

It has been discussed many times whether the cats introduced on Stephens Island were in fact solely responsible for the extinction of Lyall’s wren, or whether—as so often—a combination of several factors led to the species’ disappearance. David Quammen remarks in Der Gesang des Dodo (2001) that Lyall’s wren did not have good odds anyway: it was “risky rare (…) even in good times”. In addition, the species probably suffered from ecological naivety, which made it more trusting and thus more vulnerable to danger. Dieter Luther likewise points out in Die ausgestorbenen Vögel der Welt (1986) that “the population (…) must already have been extremely small at the time of its discovery”.

Extinction driven by collecting?

One theory holds that the already small population of Lyall’s wren was wiped out not primarily by the presence of cats on Stephens Island, but rather by the collecting of specimens for science. This view is also held by David Day in The Doomsday Book of Animals (1981). He points to contradictory reports by Rothschild and Buller about the number of collected specimens, which could cast suspicion on the collector Henry Travers. Rothschild wrote that Travers had told him that he owned all eleven specimens of Lyall’s wren, except for one that Buller had used for his scientific description. Buller commented as follows:

“I think Mr. Rothschild is mistaken in assuming that he possesses all known specimens, except the one described by me in the ‘Ibis’. Besides a pair in my son’s collection, I bought a specimen from Mr. Henry Travers for (…) Tristram, and the said gentleman has since offered me two more specimens for sale.”

The Doomsday Book of Animals. 1981. p. 118. D. Day

This makes it clear that Travers possessed at least 16 specimens and not just eleven. According to Day, the acquisition of the last specimens in particular raises questions, because it is not the first time that endangered species have been threatened with extinction by excessive collecting. Buller himself defended Travers and wrote that Travers was not to blame for the species’ extinction and that the blame lay with the cat instead:

“I cannot see that Mr. Travers is to blame at all (…). It is admitted that the cat in question would have eaten them all if Mr. Travers’s agent had not been there to save a few for science.”

The Doomsday Book of Animals. 1981. p. 118. D. Day

Interestingly, after the extinction of Lyall’s wren an essay was published in the Canterbury Press that was directed against natural-history collectors. It demanded that the government should act against them as quickly as it did against seal poachers:

“If the Government would act as promptly to prevent plunderers, commonly known as naturalists, from visiting the outlying islands and carrying away hundreds of tuataras and rare birds, as it did last year in the case of the seal poachers on the southern islands, it would earn the thanks of science and of future generations.”

The Doomsday Book of Animals. 1981. p. 118. D. Day

Although there is suspicion that collecting may have contributed to decimating the population, there is no concrete evidence that it was the primary cause of Lyall’s wren’s extinction. Rather, all reports suggest that most of the collected specimens were caught by lighthouse keeper Lyall’s cat. Given the behavior of Lyall’s wren—a small, mouse-like, semi-nocturnal, and flightless bird—it is far more likely that cats posed a much greater threat than human collectors.

Both Buller and Travers did trade the collected specimens—Travers sold them to Rothschild at high prices and later raised the prices when the species was considered extinct. Buller also collected for his own collection and sold some specimens to other ornithologists. In total, around 15 to 20 specimens of Lyall’s wren were collected between 1894 and 1899 and distributed to museums worldwide.

Travers, who made considerable efforts to find specimens of the bird, sailed to Stephens Island at least twice to search for Lyall’s wren. His reports to Rothschild indicate that he found no birds, which seems credible, since there is no evidence that would cast doubt on his statements.

Ultimately, collectors’ interest only began after the species had already been heavily decimated by cats. The temporal coincidence between reports about the cats’ activities and the rapid population decline speaks more for cats as the main cause of extinction than for collecting by scientists.

Destruction of habitat on Stephens Island

Another possible factor in Lyall’s wren’s disappearance could have been the loss of its habitat due to logging on Stephens Island. However, evidence shows that this process only began on a larger scale after 1894, making it unlikely to have been the main cause of the species’ decline.

Galbreath discovered that logging of the island’s forest began on a small scale as early as 1879 to create a track to the planned lighthouse. Further clearings took place during the lighthouse construction from 1892 to 1893 and afterwards to make room for the associated buildings. Despite these interventions, historical reports show that the island was still described as densely forested in 1898, apart from the cleared areas around the lighthouse.

Since large-scale logging of the forest did not begin until late 1903—at a time when Lyall’s wren was already extinct—most scientists agree that habitat loss played a subordinate role compared with the threat posed by feral cats.

The IUCN, however, attributes Lyall’s wren’s extinction to a combination of habitat loss and predation by introduced cats. Another example of the impact of these factors on island ecology is the fate of the Stephens Island ground beetle, which probably went extinct around 1931 due to habitat loss.

Interestingly, after Lyall left the island in 1896, the head lighthouse keeper applied for firearms in 1897 to reduce the steadily growing population of feral cats. However, it was not until 1925 that the last cats on Stephens Island were eradicated. By that time, most birds had already disappeared. Today, Stephens Island is cat-free and a strictly protected nature reserve that is home to rare and endangered species such as the tuatara (Sphenodon punctatus).

Lyall’s wren: behavior and ecology

Lyall’s wren was a small passerine from the family of New Zealand wrens (Acanthisittidae). In the Holocene, this family was once represented by seven species in four to five genera, but since humans arrived in New Zealand only two species in two genera survive.

Because only a few years passed between the discovery of Lyall’s wren and its extinction, our knowledge of its behavior and ecology is extremely limited. Most reports come from people who only saw dead specimens. The lighthouse keeper David Lyall was probably the only person who observed living Lyall’s wrens—and even he did so only twice. These few observations led to speculation about the bird’s habits and, in particular, its ability to fly.

In his first description On a new species of Xenicus from an island off the coast of New Zealand (1895), Buller mentioned that Lyall’s wren was semi-nocturnal, based on information from a correspondent. Henry Travers commented somewhat more specifically on the species’ behavior in a letter to Rothschild:

“I was told (…) that the most likely time to find it was winter, as the cat brought in most specimens at that time. Live specimens were only seen twice, and on both occasions the person who saw them had no gun with him; he declared that the bird ran about the rocks like a mouse and was so quick in its movements that he could not get near enough to it to strike it with a stick or stone.”

Travers to Rothschild, 7 March 1895, Rothschild papers, Natural History Museum, London

This quote suggests that Lyall’s wren was a ground-dwelling bird that moved nimbly among rocks, much like a mouse. The fact that people tried to catch it with a stick or stone rather than shooting it strongly suggests that it was flightless.

Worthy and Holdaway analyzed Lyall’s wren’s skeleton in their work The Lost World of the Moa (2002) and concluded that the oddly flattened skull, the flat, broad bill, and the distinctive leg bones indicate that the bird was adapted to a specialized, but still undetermined ecological niche.

The family of New Zealand wrens, formerly also known as New Zealand creepers or Māori creepers, consists of lively small birds that often forage between rocks, in dense undergrowth, or on the ground. They feed mainly on insects and insect larvae. Lyall’s wren probably built its nest close to the ground, which made it particularly vulnerable to introduced predators such as cats.

The only passerine that cannot fly

In 1895, in his paper Note on the Stephens Island rockwren Traversia lyalli, Rothschild stated that Lyall’s wren “did not fly at all”. Later, in Extinct Birds (1907), he referred to the “weak structure of the wing, which points to flightlessness”. This assessment initially met with skepticism. Some scientists doubted Rothschild’s conclusion because there was no clear evidence, or suspected that the bird had simply not been observed in flight.

Since there had been no clear confirmation of flightlessness in passerines (Passeriformes), the New Zealand paleo-ornithologist Philip Ross Millener set out to supplement Lyall’s brief observations with morphological and functional analyses. His aim was to provide evidence that Lyall’s wren was indeed flightless. Until then, this had not been possible because none of the preserved specimens had a complete trunk skeleton with sternum, coracoid, and humerus. In August, however, scientists discovered several almost complete skeletons in 1988 on New Zealand’s mainland that, for the first time, included intact sterna.

Millener’s study of the subfossil remains, published in 1989, showed that Lyall’s wren’s wings were shorter relative to its body weight than in other members of the New Zealand wrens. In addition, the wing feathers resembled those of other flightless birds, and the sternum was greatly reduced, making it unusable as an attachment for flight muscles. These results confirm that Lyall’s wren was the only known completely flightless member of the passerines.

The range of Lyall’s wren

According to historical accounts, Lyall’s wren was native exclusively to the small island of Stephens Island, about 3.2 kilometers from New Zealand’s mainland. Rothschild, however, suggested in Extinct Birds (1907) that this bird was a relict species that had once also been distributed on New Zealand’s mainland:

“It is almost impossible that this bird [Lyall’s wren] existed only on Stephen Island. It must have been overlooked on D’Urville Island or on the ‘mainland,’ where it probably became extinct—through rats and cats, and similar pests—long ago.”

Extinct Birds. 1907. p. 25. W. Rothschild

In addition to Lyall’s wren’s flightlessness, Millener was also able to confirm this supposition by Rothschild using subfossil material found in caves. The first remains of the species were identified on New Zealand’s mainland in 1976. In 1993, ornithologists Trevor H. Worthy and Richard N. Holdaway discovered additional bones of Lyall’s wren on both of New Zealand’s main islands. These came from caves and deposits attributed to owl pellets of the laughing owl (Sceloglaux albifacies), which went extinct around 1914.

Before New Zealand was settled by the Māori, Lyall’s wren was probably widespread. However, the introduction of the Pacific rat (Rattus exulans) in the 13th century by the indigenous population likely led to its disappearance on the mainland. During the last ice age, Stephens Island was still connected to the mainland, which would have enabled the flightless Lyall’s wren to reach it.

The bird disappeared from the mainland before Europeans began settling New Zealand from the 1870s onward, and it survived only on Stephens Island. This suggests that a population decline had already begun even without cats and that the species found refuge on the remote island.

In their book Cat Wars: The Devastating Consequences of a Cuddly Killer (2017)—and also Errol Fuller in Extinct Birds (2000)—Peter P. Marra and Chris Santella allow for the possibility that the fossil evidence from the mainland does not necessarily have to come from Lyall’s wren. Genetic or morphological differences that could distinguish it from similar species have not yet been demonstrated. They also consider it plausible that the finds come from different, similar species that lived in isolation for millions of years.

Museum specimens of Lyall’s wren

The number of known museum specimens of Lyall’s wren varies by source between 16 and 18, apart from subfossil remains. These specimens were collected on Stephens Island or caught there by resident cats. Rothschild owned nine specimens, all collected between July and October 1894. Of these, three are in the Natural History Museum in London, four in the American Museum of Natural History in New York, one in the Academy of Natural Sciences in Philadelphia, and another in Harvard’s Museum of Comparative Zoology in Cambridge, Massachusetts.

The specimens collected by Buller date from 1894 to 1899. A female bird dated to 1894 is now in the Carnegie Museum in Pittsburgh. Another pair, in the collection of Buller’s son and dated to 1899—possibly acquired earlier—is in the Canterbury Museum in Christchurch, New Zealand.

Another specimen was acquired by Buller for the English ornithologist Henry Baker Tristram and sold in 1898 to the World Museum in Liverpool. The Museum of New Zealand Te Papa Tongarewa in Wellington also has a mounted specimen with no precise provenance data, which may likewise have come from Travers. In addition, the Otago Museum in Dunedin also holds a specimen of Lyall’s wren.