Which albatross? A discussion:
Letís try and work it out (and eliminate other species; those likely in the Humboldt Current, and those the bird resembles):

(1)    The bird is certainly not from the Shy Albatross complex  (White-capped, Salvinís, Chatham etc) of  that all seem sure. I am positive it is not one of the Shy group, as I have a lot of experience with these, and along the Humboldt we had many over the three-week cruise. Of the twelve replies to my request for help only one person put Shy (salvini/eremita) forward and this seemed retrieved from fieldguides, rather than experience

(2)    Two people suggested hybrid origin, particularly Laysan x Black-footed. I have seen two photographs of these hybrids and this bird resembles neither, in plumage nor structure. Neither species occurs along the Humboldt

(3)    One very competent Australian seabirder held out that the bird was a Yellow-nosed (of the Atlantic form chlororhynchos) but the location would have been extraordinary. Are there any records from the Pacific Ocean?

(4)    Grey-headed was favoured by six correspondents, though two did feel there were some anomalies with the plumage of this bird. For example, was the head too pale? I was concerned about this also, but remember the head does indeed go paler from juvenile to immature

We should now introduce the age of this individual to the debate - it would seem to be 3 to 4 years, based on Photo 4 Page 1 (and it looks to be in poor condition). The outer remiges are old, inner new, and some of  the coverts have been replaced, those at the carpal missing or worn away. In normally developed feathers on albatrosses this would take some 3 to 4 years. Pete Milburn in Australia reckoned the bird was probably 3+ years old, but noted that it seemed to have some developmental problems. If the bird were a Grey-headed Albatross the bill colouration would be of a first-year bird while the head and neck were a mixture of juvenile and adult patterns. Three year-old Grey-headed are notoriously variable in appearance, some are dark headed, some almost white, and this was confirmed by others writing from the Falkland Islands. The head and neck patterns of these older immature Grey-headed Albatrosses do get scrambled. Bill colouration with birds of this age can vary from mostly dark, through subdued adult pattern, to slate-brown with a darker tip. Some thought the bird seemed heavy in structure to most Grey-headed Albatross

(5)    Buller's Albatross was put forward but replies from two in Australia, plus another, were firm in that it was not a Bullerís Albatross. They never have all dark bills (as per HANZAB). The juvenile has a pale bill with a dark tip and by the third year has a bill similar, if duller, than the adult. Immatures are smart-looking birds with adult-like heads (there are some on other websites, they are not like the photos above) - the bird above does not fit with Bullerís of any age

(6)    We have now to introduce Pacific Albatross. This taxon is sometimes classified within Bullerís (monotypic), or as a race of Bullerís (although the current scientific name platei is not recognised), or as a distinct species, depending on the authority. This is the maverick, the unknown in the debate, as the literature is weak on the development stages of immature Pacific, even HANZAB stating Ďimmatures undescribedí. Mike Imber thought the bird was Pacific (eliminating Grey-headed on the relative lack of skin visible around the base of the culminicorn rearwards from the nostrils), and Al Jaramillo in Chile also plumped for Pacific (Bullerís) Ė Alís expertise would be with this form along the Humboldt Current, though interestingly the vast majority there are adults. If this is Pacific Albatross then it differs from Bullerís in this immature plumage, bill depth and bill colour! It would be another reason, adding weight, to splitting this form and treating it as a separate species
Postscript 4 January 2005
Edward Soldaat sent an image (left) of Grey-headed Albatrosses and he juxtaposed the head of our bird, on the right. Some commented that structural differences seemed evident between ours and the two Grey-headed shown e.g. Grey-headed had a shorter bill, lighter cheeks and rounder head shape. Even measurements of the bill, admittedly from the photograph, were more to Bullerís (Pacific)
Grey-headed Albatross (two birds on left and inset the mystery bird)
Mike Carter still thought Yellow-nosed Albatross should be in the frame and that the elimination of this species should not be on geographical grounds alone. Yellow-nosed though always shows a more concave upper mandible and, more importantly, the bases of the culminicorn, latericorn, ramicorn create a straight  line where meeting the feathering - this gives the impression that the bill is 'stuck-on'. Our bird though shows a noticeable 45ļ angle at the base of the ramicorn, at the conjunction with the head.
Yellow-nosed Albatross - far left and left
Edward Soldaat then Emailed me an enlarged photo of the head which he had enhanced by using Adobe Elements software (brightness +21, contrast Ė30). The result was quite extraordinary as can be seen from the photo below. It now, by magic, shows yellow on the lower mandible! This could not be seen on the original photo or in the field
The NEW enlarged and enhanced photo of the mystery albatross
This enhanced shot effectively eliminates Yellow-nosed Albatross, which does not have yellow on the lower edge of the lower mandible (it does show yellow at the lateral base of the ramicorn).

The head and bill resembles the Bullerís here yet this enlarged photo shows another feature, one that had only been in the discussion with Yellow-nosed. Note that the culminicorn narrows at its base and there appears a small gap between this and the feathering - is this bare skin, the naricorn curling up? The culminicorn on Bullerís (both forms) expands to broaden at the proximal base yet Grey-headed narrows - hereís photos of both species showing the culminicorn shape - and so we come full circle, maybe this is a Grey-headed after all?
Note the shape at the base of the culminicorn on Buller's (far left) and Grey-headed (left)
At the moment (Jan '05) the jury may still be out? Is the mystery albatross
a retarded immature Grey-headed Albatross or a Pacific (Bullerís) Albatross in an undescribed immature stage?
I would like to thank the following for entering this forum and answering my questions: Karen Baird (NZ), Harry Battam (Aus), Mike Carter (Aus), Trevor Hardaker (SA), Mike Imber (NZ), Al Jaramillo (Chile/US), Pete Milburn (Aus), Richard Podolsky (US),
Tim Reid (Falklands), Sav Saville (NZ), Edward Soldaat (NL), Richard Thomas (UK BirdLife)
Final Postscript 22 February 2005
At the last update identification was divided between Grey-headed and Pacific (Buller's) Albatross. What we have learnt since:
(1)    Bullerís can show bare skin at the base of the culminicorn (as per Grey-headed - earlier in the debate this was considered a feature for the bird being Grey-headed Albatross)
(2)    The width of the naricorn (the skin between the horny culminicorn and latericorn) is very much wider just behind the nostrils in Grey-headed
(3)    The semi-orbital mark is a narrow crescent on Pacific (and Bullerís) and is a different shape on Grey-headed being straighter, larger, more triangular, and broader at the underside of the eye
(4)    Pacific (and Bullerís) appears to have a sloping forehead, the head less rounded than Grey-headed
(5)    The yellow at the tip of the culminicorn is greater in Pacific (and Buller's) than in Grey-headed, and the bird tends towards the former (but this was a dubious clue in this bird's stage of maturity)
(6)    ĎPacificí has a larger deeper bill than Bullerís
(7)     This bird, a ĎPacificí Albatross, shows many differences from nominate Bullerís. It is either
    (a)    simply an odd bird in poor condition or
    (b)    shows an unrecorded immature phase (itself very different to that known for Bullerís Albatross!)
An interesting puzzle, and a learning curve for all involved!
Thanks again for the inputÖ
THE ANSWER - the bird is a 3+ year-old Pacific (Bullerís) Albatross