A CENTENARY CELEBRATION FOR THE INACCESSIBLE ISLAND RAIL - A FLIGHTLESS MINI-BIRD FROM ATLANTIS!

 Illustration of the Inaccessible Island rail (public domain)
A hundred years ago this very same month, one of the most diminutive but delightful of all living birds was formally added to the zoological catalogue of recognised species. So here, as a centenary celebration of this remarkable little creature's official unveiling, is a concise history of its discovery.

Inaccessible Island is a tiny islet of the Tristan da Cunha group, sited in the south Atlantic roughly midway between southern Argentina and South Africa, and would have little claim to fame, were it not for a very peculiar member of its avifauna. The species in question is a miniscule rail, only 5 in long (little larger than a newly-hatched chicken), and with such tiny, poorly-formed wings that it is totally flightless, making it the world’s smallest extant species of flightless bird.

  Remaining elusive among its island's abundant tussock grass (© Brian Gratwicke/Wikipedia – CC BY 2.0 licence )

Its habit of scampering swiftly through the island's wide expanses of dense tussock grass thus makes it seem to the casual observer more akin to a mouse than to a bird. This illusion is enhanced by its strange feathers, which are decomposed (i.e. atrophied) and hair-like. Its upperparts are reddish-brown, its underparts are dark grey, and its belly, flanks, and wing-covert feathers bear paler bands. 

A remote spot, not readily reached, Inaccessible Island was well-named. Due to its inaccessibility, its minute rail (found nowhere else in the world) escaped formal scientific recognition until 1923, when the Reverend H.M.C. Rogers, resident chaplain on Tristan da Cunha, collected some skins of it in response to a request made by the Shackleton-Rowett Expedition's naturalist, a Mr Wilkins. The expedition had visited the island group a little earlier, and had heard the locals speak about the tiny 'island hen' of Inaccessible, but had been unable to travel there to seek it out.

  Portrayed in Rose Annie Rogers's book The Lonely Island, published in 1927 (public domain)

Nor was that the first scientific expedition to have learned about this mysterious mini-bird without succeeding in procuring a specimen to confirm its reality. In 1905, Lord Crawford had sailed to its island homeland aboard his yacht Valhalla with the express purpose of collecting a specimen after learning of its existence there, but he failed to accomplish his goal. Earlier still, in October 1873, the famous Challenger Expedition of 1872-1876 had visited Inaccessible Island, where its chief scientist, Sir Charles Wyville Thomson, learned of its diminutive denizen and recorded observations that had been made here by two German brothers, the Stoltenhoffs, while residing there during the past two years, but he was unable to obtain a specimen. (Consequently, this elusive bird was actually a cryptid during that 50-year time span, from 1873 to 1923 – known to the locals but officially unconfirmed by science.)

Happily, however, these unsuccessful attempts no longer mattered when, on 5 July 1923, two of the skins collected by Rogers arrived at what was then the British Museum (Natural History), and were described that same year by Percy R. Lowe, who named the new species Atlantisia rogersi. 'Atlantisia' alludes to the belief by some workers that the Tristan da Cunha islands are remnants of the fabled sunken continent of Atlantis.

  Hand-held, highlighting its tiny size (© Brian Gratwicke/Wikipedia – CC BY 2.0 licence )

Previously little-studied, during the 1980s A. rogersi was the subject of a detailed field survey by South African researchers Drs M.J. Fraser and W.R.J. Dean, and Dr I.C. Best from Bahrain, published in 1992. More recently, in 2018, a further study proposed that this species should vacate its memorable monotypic genus, Atlantisia, and instead be rehomed within the pre-existing genus Laterallus, hitherto containing 12 species of crake. Consequently, it is now known as Laterallus rogersi, which may be more accurate taxonomically but is much less romantic – give me Rogers's bird from Atlantis any time!

This ShukerNature blog article is excerpted and expanded from my book The Encyclopaedia of New and Rediscovered Animals .