A tale of two bills: the reedhaunters

facebooktwitterReedhaunters 2Our research is reliant upon the Natural History Museum’s ornithological collections- comprising thousands of specimens, amassed over centuries from across the globe, preserved, recorded and studied. The scale and scope of our project means we come into contact with a huge array of this material every day, working across taxa to select individual specimens that act as representatives of a species for our dataset. We handle them, assess their condition, transcribe and photograph their label data, create 3D images of their bills and return them to their place amongst the taxonomically arranged cabinets. This is typical of the way wide-ranging scientific research utilises natural history collections- as ordered snapshots of biological data- but this is only one way of viewing and using them.

Having previously worked on the collections from a historical perspective, where focus more often lies on the individual artefact, studied and prized for its own story, it has been an interesting shift to consider these alternative approaches to collections. There are still occasions, however, when the habit of checking specimen labels, not just for sex and locality data, but also for handwriting, collector’s names and annotations can highlight the biography of a specimen and the species it represents. The reedhaunters, comprising only two species, are a prime example of this.

The specimen of straight-billed reedhaunter (Limnoctites rectirostris) we selected for scanning and landmarking is identified as a type- the specimen from which a species was formally described. The Natural History Museum is keeper of the largest number of ornithological types in the world, stored securely from the main series, and often harbouring their own intriguing stories alongside their immense scientific value.

The labels on this particular specimen revealed that the bird had been collected by none other than Charles Darwin  (1809-1882) during the second voyage of HMS Beagle before being sent to London via the great ornithologist and scientific artist John Gould (1804-1881). It remained one of the only such specimens known to science for a further century. Furthermore, Gould used this specimen in his illustrations for the Zoology of the voyage, a publication that immortalised the collecting activity on the infamous expedition:

John Gould's original illustrations of the Reedhaunters, with Limnoctites rectirostris thought to have been painted directly from the type specimen

John Gould’s original illustrations of the Reedhaunters, with Limnoctites rectirostris thought to have been painted directly from the type specimen

The reedhaunters are marsh-dwelling ovenbirds that were first collected by Darwin whilst in Uruguay in the 1830s. As with many of his ornithological specimens, Darwin sent the prepared skins back to London where John Gould set about studying and identifying them. In so doing, Gould created the new genus Limnornis for the two species, and (particularly interesting for our study) named them individually according to their bill differences, the straight-billed reedhaunter (Limnornis rectirostris) and the curve-billed reedhaunter (Limnornis curvirostris).

Our scans of the curve- and straight- billed reedhaunters, with the former taken from Darwin's actual 19th century specimen

Our scans of the curve-billed and straight- billed reedhaunters, with the latter generated from Darwin’s actual 19th century specimen

Since Gould’s original identification of these species and despite Darwin himself saying he was unable to notice any behavioural differences between the species, they have undergone a number of taxonomic revisions. Increased understanding of differences between the two has seen them widely placed in separate monotypic genera (Limnornis and Limnoctites) but they have still widely been regarded as each other’s closest relative.

Building on this, contemporary research has highlighted that beyond broadly similar plumage, there are more significant differences between these species than their historical treatment would have us believe. With significantly different tail structure, nest building behaviour and egg colouration (L. curvirostris lays greenish-blue eggs, unusual within Furnariidae), additional studies considering distribution and molecular systematics have built a case for their long-held taxonomic relationship to be reconsidered. You can read one such paper in full here.

The whole process of working with historical specimens requires learning from the physical artefact, building on our existing knowledge by combining new methods and insights with this long-ago collected material. So when you log on to MarkMyBird and begin landmarking a bill, spare a thought for where the original specimen came from, at what time, whose hands it has passed through or, indeed, what new light may be shed on its relationships with other species as a result of modern scientific studies.