27th January 20202
Royal Tern has been split into two species by the IOC as part of the the latest (10.1) update to its World Bird List.
West African Thalasseus albididorsalis has been recognised as a different species to [American] Royal Tern T maximus, and has been dubbed West African Crested Tern.
The news comes as little surprise – 2017 research showed that West African Crested Tern was in fact a sister taxon of the smaller Lesser Crested Tern rather than similar-looking [American] Royal Tern, and that its then treatment as a subspecies of Royal Tern was misleading. This was supported by both the mitochondrial and nuclear DNA. These revelations come despite the fact that Royal and West African Crested Terns are morphologically near-identical and, in many cases, nigh on impossible to separate in the field.