How Tibbles the cat single-handedly caused a Victorian-era extinction
How did one cat take out an entire species of bird in the 19th century? Dr Ross Barnett explains more about how human behaviour through history has caused devastating impact on rates of extinction
Before the dodo, the notion of human-caused extinction was unimaginable. However, in the three and a half centuries since the dodo disappeared (the last widely accepted sighting was in 1662), the extinctions of species driven by human behaviour have occurred widely across the globe – driven by both habitat loss and hunting.
Few stories of extinct animals are as poignant as that of the Stephens Island wren. This flightless bird was wiped out in rapid fashion – not by poaching or habitat destruction, but by a single cat
Speaking on the HistoryExtra podcast, palaeogeneticist and extinction expert Dr Ross Barnett discussed the history of human-caused extinctions.
The story of the wren's extinction begins in 1894, when a lighthouse keeper on Stephens Island, New Zealand, introduced a female cat named Tibbles to the remote outpost.
Cats had never before been present on Stephens Island, a small island 55 miles from Wellington off New Zealand’s South Island. And Tibbles’ arrival, explains Barnett, “decimated – exterminated – the last population of this unique flightless songbird.”
The Stephens Island wren was a flightless species of bird which lived in holes in the ground, an existence sometimes characterised as a ‘Hobbit-like’. Peter P Marra and Chris Santella described the bird in their book Cat Wars (2016, Princeton University Press) as: “Equipped with large feet and a short tail, it ran low to the ground among the shoreline rocks or jumped from branch to branch through thick tangles of knotty shrubs.”
Most importantly to this tale, the Stephens Island wren did not need to fly. “There was no need to leave the island or the ground for long,” explain Marra and Santella. “Food was available throughout the year, and the species could breed on the island.”
And, fatefully, there were no predators.
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But in 1894, the wren’s existence changed. Tibbles quickly became more than a companion to the lighthouse keeper, turning into an unwitting agent of destruction.
As Marra and Santella wrote: “Cats do not always kill out of hunger”. They can stimulated by the chase and other prey-return behaviour that some have suggested as cats trying to teach another cat or perhaps even a human to hunt.
“Tibbles, once on the island and allowed to roam, doing only what her instinct told her to do,” write Marra and Santella, soon began bringing the small birds, also known as Lyall birds – “sometimes whole and sometimes half-eaten.”
“By 1895, within a year of the cat turning up on Stephens Island, there were no more Stephens Island wrens,” says Barnett.
But the blame does not rest solely on Tibbles. “Here we have a complete extinction down to humans,” says Barnett, pointing out that the introduction of the cat was a human decision.
“Essentially, the proximate cause is the cat. But humans have brought the cats – and they've decimated the population.”
But it’s not just about cats and wrens. Barnett tells the story to highlight the broader pattern of human-caused extinctions throughout history.
“As long as humans have been around, as long as we've been moving around the planet, I think we've been causing extinction.”
The fate of the Stephens Island wren mirrors other extinctions. The dodo, famously wiped out in the 17th century by human influence, similarly had no natural defences against introduced predators.
“Once we turn up and start modifying the landscape in these island environments, which are naive to our presence, species like the dodo or the wren stand no chance,” says Barnett.
Barnett also highlights the broader environmental impact of these human-caused extinctions. "The one that tugs at my heartstrings the most is the Steller’s sea cow," Barnett reflects.
The Steller’s sea cow, a giant sea creature which was related to the dugong and grazed on kelp forests, was driven to extinction by human hunting in a matter of decades after its 1741 discovery by naturalist and explorer Georg Wilhelm Steller, when he and his sailors were shipwrecked on Bering Island in the North Pacific during an expedition.
The stranded sailors hunted the mammals for survival,
The rapid demise of the Steller’s sea cow was not unlike the fate of the Stephens Island wren. Once discovered, the gentle giant found itself vulnerable to human exploitation.
After the sailors’ stranding, and after word of the species spread (bringing more hunters), the Steller’s sea cow was extinct by 1768.
“That's less than 30 years between discovery and extinction,” says Barnett.
"They just sound like really beautiful animals that were absolutely destroyed by desperate people in desperate times."
Authors
James Osborne is a digital content producer at HistoryExtra where he writes, researches, and edits articles, while also conducting the occasional interview