While it is always heartening to find out that more species have been discovered or split from existing forms, lumping and reversal of taxonomic decisions also occurs regularly. We present here a round-up of recent deletions and merges from the International Ornithological Congress (IOC) World List, though not all have been accepted by other authorities as yet.
Vietnamese Pheasant Lophura hatinhensis has been deleted from the IOC world List owing to the likelihood that the form is in fact a hybrid between Edwards's Pheasant L edwardsi and Silver Pheasant L nycthemera. The original description has been found to be inadequate. However, further online discussion among taxonomists has underlined that the full variation of L edwardsi is unknown and that the form known as hatinhensis may well be an inbred form, an extreme of its natural variation or a valid subspecies. The least likely option is that of a hybrid, it seems, but the taxon is almost certainly invalid as a species and should thus most probably be reincorporated into L edwardsi. Also, the form has not been reliably recorded since 2000 and may be extinct, as all known sites for it have now been deforested, but its new status may mean that conservation dollars for it will be hard to find.
While the Neotropical avifauna is often looked at as the most 'overlumped' in the world, it seems that ornithologists should be wary of being too keen on splitting, too. Despite a paper recommending the splitting of Mitred Parakeet Aratinga mitrata, a south American parrot species, into Hocking's Parakeet A hockingi and Chapman's Parakeet A alticola having been published in 2006, and this revision being considered by other authors even until 2010 and instituted by the IOC. The South American Classification Committee (SACC) states that, although both forms may prove to be 'splittable' as full species, not enough evidence has been accumulated to satisfy this conclusion, and awaits genetic evidence for support.
Two South American warbler species - White-bellied Warbler Basileuterus hypoleucus and Golden-crowned Warbler B culicivorus - have also been re-limped by the SACC and IOC, due to their genetic inseparability and the great deal of response that each 'species' has to each others' vocalisations. The species now becomes B culicivorus, but the validity of B hypoleucus is indeterminate until further work is done, and it may even turn out that it is merely a colour morph of B culicovorus.
Eastern Rockhopper Penguin Eudyptes filholi of the sub-Antarctic islands of the Indo-Pacific Ocean has been considered to be genetically distinct from Southern Rockhopper Penguin E chrysocome, by at least two recent papers, but the evidence is still lacking for it to be considered a full species, as some have suggested.
Uhehe Fiscal Lanius marwitzi is deleted by the IOC and becomes a subspecies of Common Fiscal L collaris, as already discussed by Birdwatch and described in Fuchs et al (2011). However, there is still much work to be done on fiscal shrikes, and the last word is far from being uttered.