Although so tiny in size the Stephens Wren was an altogether remarkable creature. It may have had the smallest natural range of any known bird. It may have been the only flightless passerine. It may have been the only creature discovered and then exterminated by a single animal – a lighthouse keeper’s cat.
During 1894 this single domesticated predator brought to its owner a series of tiny corpses. These grisly little events occurred on the small island of Stephens lying in the Cook Straits, the channel that separates New Zealand’s North Island from the South. The lighthouse keeper in question – a Mr Lyall, after whom the species is scientifically named – was something of an amateur ornithologist. He preserved the specimens and, realizing that the birds might be rather unusual, passed them on to a dealer. Soon the majority of them were shipped to Europe where most were bought by Walter Rothschild, the celebrated natural-history collector, who was then busy assembling his wonderful museum at Tring in Hertfordshire, England.
Thus, Xenicus lyalli became known to science. By the time its existence was broadcast to the world, via the ornithological journal Ibis, the species was already extinct. The cat had stopped bringing in dead specimens and the birds were never seen again. It seems likely that forest clearance for the construction of the lighthouse, in 1894, may also have made a significant contribution to the bird’s demise. The only human observation of Stephens Wrens was made by the lighthouse keeper himself. He saw the birds twice, both times in the evening. Disturbed from holes among the rocks, they ran fast in the dusk, like mice. They never tried to take to the air and this suggestion of flightlessness is borne out by the poorly developed wings which indicate weak flight at best.
Skeletal remains of what seems to have been a flightless wren have been found on the New Zealand mainland. Some writers believe that this proves that Stephens Wrens were once widespread in New Zealand and that the birds discovered during 1894 were simply a relict population, but it seems far more likely that the skeletal remains come from a similar but quite separate creature. There are a number of objections to the case for the Stephens Wren being associated with the mainland skeletal remains. First, what material were the bones compared with? Second, how did a wren that was flightless, or almost so, manage to reach Stephens Island? Sir Walter Buller (1905), the great chronicler of New Zealand birds, quoted from a correspondent of The Canterbury Press who had written the following:
And we certainly think that it would be as well if the Marine Department, in sending lighthouse keepers to isolated islands where interesting specimens of native birds are known or believed to exist, were to see that they are not allowed to take any cats with them, even if mousetraps have to be furnished at the cost of the state.
Bull. Brit. Orn. Club 4: 10.