Northern Royal Albatross Diomedea sanfordi is split from Southern Royal (formerly Royal) Albatross Diomedea epomophora (Clements 2007:9)

Summary: The newly split Northern Royal Albatross of South and Chatham islands can usually be distinguished at sea from the more numerous Southern Royal from Auckland and Campbell islands, if views are sufficiently good and photos show the leading edge of the wing.

Details: The Northern Royal Albatross D. sanfordi was originally named as a full species (Murphy 1917), but it is very closely related to the Southern Royal Albatross D. epomophora (Chambers et al. 2009). Nevertheless, it is fairly readily distinguished on plumage at all ages, and also is generally smaller. Northern and Southern Royals occupy largely separate breeding ranges in the New Zealand region, though there are a few records of mixed pairs at Taiaroa Head, South Island and Enderby Island, Auckland Islands (Taylor 2000). Despite their close approach and some level of gene flow, they have however maintained a greater degree of phenotypic difference than that found within any other species of albatross. Levels of genetic divergence between albatross species are typically low, and rarely, hybridization occurs even between other unequivocally specifically distinct albatross species (Phillips et al. 2018, Jones et al. 2020).

Although long treated as conspecific, the ACAP (Agreement on the Conservation of Albatrosses and Petrels, https://www.acap.aq/documents/working-groups/taxonomy-working-group/taxonomy-wg-reports/195-3rd-report-of-taxonomy-wg-2007/file) considers them separate species, as do numerous authorities (e.g., Gill and Donsker 2009, IOC v.2.1, del Hoyo and Collar 2014), and several field guides. While their specific status will remain a matter of opinion, WGAC and the Clements/eBird checklist (Clements et al. 2023) have now adopted the split.

[Most IDs are at the subspecies level, so this split shouldn't send too many to the genus level]