Rio de Janeiro Antwren – the mystery continues

David Beadle’s superb Illustration of Rio de Janeiro Antwren from February 1997 (© David Beadle)

Almost exactly twenty years ago, renowned UK birders Guy Kirwan, Rodd McCann, Rob Williams and Canadian bird artist David Beadle visited REGUA, returning a year later in the company of the late Argentine birder Juan Mazar Barnett. Staying at the modest REGUA research accomodation, they had come to find the Rio de Janeiro Antwren Myrmutherula fluminense, following the sighting by Stephen Knapp which had electrified the birding world and put REGUA on the international map. The birders all saw the bird in a secondary forest at 100m elevation and I even asked David if he could draw us a picture of this extraordinary bird.

The Rio de Janeiro Antwren is a monotypic species that lies in Professor Luis Gonzaga’s collection at the Federal University of Rio de Janeiro (UFRJ). During Professor Gonzaga’s doctorate field work in 1982 he found and collected a common antwren in one of his mist nets in the lowland forest near Magé, some 30 miles away from REGUA as the crow flies. Upon further study he realized that it was not the White-flanked Antwren Myrmutherula axilaris and named it Myrmutherula fluminense.

Immature male White-flanked Antwren caught by Fabio Olmos, November 2003 (© Alan Martin)
Immature male White-flanked Antwren caught by Fabio Olmos, November 2003 (© Alan Martin)

Over the years, birders came to REGUA to try to see not only this bird, but also other species of Atlantic Forest birds, and the REGUA organization grew to become the respected conservation project it is today. Birders and naturalists from around the globe visit REGUA and stay at our lodge. The results of our habitat protection, partly funded by visitation to REGUA, have been inspirational, but the Rio de Janeiro Antwren was never seen again, suggesting that it may well have been the White-flanked Antwren or even a possible hybrid.

Brazilian ornithologist Fabio Olmos visited and mist-netted in exactly the same area six years later and caught an immature White-flanked Antwren offering doubts as to the real identity of that mysterious bird that David and friends saw.

Professor Gonzaga kept the bird for over 15 years until it was given the ultimate test, the DNA test, and what did he find? The results showed that the bird was completely different from the Myrmutherula genus. Now he has a single bird of a new unnamed genus, probably the rarest bird in Brazil!

On the search now are Brazilian ornithologists Luciano Lima and Rafael Bessa, Rafael famous for rediscovering the Blue-eyed Ground-Dove Columbina cyanopis, missing for over 75 years. They are involved in a field project sponsored by American Birding Conservancy to search the lowland forests for the mysterious bird. Could others lurk out there in similar secondary forest? Luciano and Rafael have completed their fieldwork and have some ideas, but we are left with doubts. However, it was chance to tell them the story of the bird that put REGUA on the map, that brought generous donors to help establish this lowland reserve and all its programmes in conservation of the Atlantic Forest. There are still many small patches of forest out there so perhaps we have not heard the last of this enigmatic bird!