Based on genetic work by Robertson & Nunn (1998), ACAP (Agreement on the Conservation of Albatrosses and Petrels)
split the former Shy Albatross (Diomedea cauta) into four species as follows:
- Shy Albatross (Thalassarche cauta)
- White-capped Albatross (Thalassarche steadi)
- Salvin's Albatross (Thalassarche salvini)
- Chatham Albatross (Thalassarche eremita)
HBW follows the above taxonomy but admits that Shy/White-capped do not qualify as separate species under their
scoring system. Clements/eBird, IOC and AOU (followed here) lump Shy with White-capped Albatross under the name
White-capped while H&M4 lump all four under the name Shy Albatross as was standard before the ACAP split.
The gray bill with yellow tip makes our bird an adult of the expected New Zealand breeding population T. c.
steadi which lacks yellow on its culmen (top of upper mandible). The nominate race (Shy Albatross) which breeds
on Tasmania is a vagrant to New Zealand and is very difficult to distinguish from T. c. steadi. Some Australian
experts suggest (pers. comm.) that Shy has whiter underwings extending as a point at the tip, while White-capped
is darker there (more like Salvin's). Shy also tends to have whiter heads than White-capped. Canon PowerShot SX50
HS.
References:
Carboneras, C., Jutglar, F. & Kirwan, G.M. (2017). Shy Albatross (Thalassarche cauta). In: del Hoyo,
J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World
Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/52507
on 6 February 2017).
del Hoyo, J., Collar, N. & Kirwan, G.M. (2017). White-capped Albatross (Thalassarche steadi). In: del
Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of
the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/467266
on 6 February 2017).
Robertson, C.J.R. & Nunn, G.B. (1998) Towards a new taxonomy for albatrosses. Pp. 13–19 in: Robertson, G. &
Gales, R. eds. (1998). The Albatross, Biology and Conservation. Surrey Beatty & Sons, Chipping Norton, UK.
Sagar, P.M. 2013 [updated 2016]. White-capped mollymawk. In Miskelly, C.M. (ed.) New Zealand Birds Online. www.nzbirdsonline.org.nz
Shirihai, H. (2007) A Complete Guide to Antarctic Wildlife. The Birds and Marine Mammals of the Antarctic Continent
and the Southern Ocean. 2nd edition. A&C Black, London.