Mystery birds of the South Pacific
The Voyages of Discovery led by James Cook in the 18th Century brought amazing new insights into the natural world, but also plenty of mysteries which have lasted well into recent times.
One mystery concerns an assuming little bird that used to exist on one of the South Pacific Islands. Somewhere within the Bird department of the Natural History museum in London is a specimen of unknown provenance: known only as specimen 12.192. The confusion began when Walter Buller, a New Zealand naturalist misread the label naming the unidentified specimen A. mavornata, a meaningless binomen. English ornithologist Richard Bowdler Sharpe, considering the name of the species to be purely nonsensical changed it to A. inornata, an invalid binomen according to ICZN rules (Indeed, only the first published name takes precedence.)
Let’s turn the pages back to 1774, when Johan Reinhold Forster, a German Naturalist and his 19 year old son Georg embarked on HMS Resolution. They accompanied James Cook on his second voyage to the Pacific and reached the small island of Rai’atea, now in French Polynesia, in the summer of that same year. The team captured a rufous brown bird, no bigger than a song thrush and Georg was charged with recording it, which he did in a beautiful watercolour drawing. Sadly, this bird went extinct for unknown reasons and was gone by the time the Island was visited again in 1850. Young Forster’s drawing is the only visual evidence of this bird that remains today.
However, Sharpe caused further confusion by identifying specimen 12.192 with Forster’s watercolour, despite lots of discrepancies between the painting and the specimen. This incorrect association perpetuated until the late 20th Century when Olson, an American Biologist, solved the mystery with research. He found that the specimen was not the bird that Forster had encountered.. It was one that had been shot in Mauke, another island in the Pacific, in 1825. According to Andrew Bloxam, the man who shot it, it was « killed hopping about in a tree ». Oddly enough,the bird also went extinct before ornithologists visited Mauke again less than fifty years later. Bloxam’s work had originally been published in a very abbreviated form, so it wasn’t obvious there was any specimen collected by him at all, or that it was the same bird as the specimen in the collection.
The story behind the extinction of both birds is perhaps not such a mystery. Indeed, the exploring ships of the eighteenth century brought destruction in the form of vermin such as rats and cockroaches. This did not go unnoticed by Andrew Bloxam during his visit in 1825: « We saw quantities of rats with long tails, different in appearance from the common South Sea rat and resembling in color and almost in size the Norway rat. We saw them running about the wood in great quantities »
These rats were most probably the cause of the Raiatea starling’s extinction, and the Mauke starling most probably suffered a similar fate.
It has been suggested that Forster’s bird was a thrush or honeyeater, but in fact it belongs to the same genus as the Raiatea starling: Aplonis. Both species were very vulnerable to land mammals brought by ships.The fact that they belong to the same genus is not surprising however as islands so distant from the mainland were only colonised by a few species. Once settled, these island populations had plenty of evolutionary time to differentiate into separate species in the specific environments of each island.
There are several morals to this story. The first is, of course, that we have to be very careful not to destroy things as we study them. The ravages of ground mammals on ground nesting birds with the arrival of humans to isolated places is a very familiar pattern. The second is, perhaps, how elusive nature can be. Even with specimens, drawings, eyewitness accounts, these two species were conflated for decades. They did, of course, look rather similar, but it also demonstrates just how much there might be that we still don’t know, even about relatively well-understood taxa such as birds. More mysteries could exist right under our noses.
