Research published on phylogeny of weaverbirds shows Aldabra fody as separate species |23 April 2018

In 2015, the Seychelles Islands Foundation (SIF) published the results of a genetic study conducted by Dr Janske van de Crommenacker, investigating the impact of a group of Madagascar fodies that had arrived on Aldabra from the adjacent Assumption Island where they were introduced by people.

The study confirmed that the two different fodies had hybridized, which jeopardized the genetic structure of the Aldabra fody.

The study, published in the peer-reviewed international scientific journal ‘Diversity & Distributions’, thereby confirmed that colonisation of Madagascar fodies on Aldabra was not a natural event, and it justified their eradication (as well as the eradication of the hybrids).

The study’s comparison of the Aldabra fodies’ genetic structure with many of its relatives in the Western Indian Ocean, was also useful for another purpose: the reassessment of the taxonomic status of the Aldabra fody.

With 24 more genetic samples added to the thus far, rather weak evidence in literature, the study provided a robust confirmation that the Aldabra fody should be re-classified as distinct species rather than sub-species, i.e. Foudia aldabrana instead of Foudia eminentissima aldabrana.

It is very rewarding that this publication has also initiated some recent events that are vital to the bird’s conservation status. Firstly, the Aldabra fody is recognised and mentioned as a separate species in a recent publication on the phylogeny of weaverbirds (de Silva et al. 2017, Molecular Phylogenetics & Evolution), which hugely contributes to the general acknowledgement of the Aldabra fody as a distinct species. Secondly, the Aldabra fody is currently being proposed on the BirdLife Globally Threatened Birds Forum for uplisting on the IUCN Red List. The Aldabra fody currently still holds the IUCN Red List status of ‘Least Concern’ that actually applies to the much more widely distributed Foudia eminentissima, under which it was previously considered a subspecies. On the forum, it is proposed that the Aldabra fody should be uplisted to Vulnerable, based on the recognition that the bird is prone not only to introduced predators but also to hybridisation which could cause future declines in this isolated species.

We hope that the Red List uplisting goes ahead, this will emphasise the importance of appropriate conservation management of the species and aid in the direction of resources.

SIF