8 Apr 2018

8 Apr 18 - Atlantic Odyssey - Day Eleven: At Sea From South Georgia To Gough Island

Today was another day at sea on the crossing from South Georgia to Gough Island. There were a lot more Seabirds around today as we were due to reach Gough Island in the late afternoon of the following day. After the rough weather earlier in the journey from South Georgia, all the Birders were keen to be on deck for a good part of each day.
A lot of Birders liked to spend time at the bows: Whereas I had realised that there was a better overall view from the bridge wings
Richard & Bridget Lowe: Confirming it was still cold outside
My Ozzy mate Geoff 'Bush Tuckerman' Jones: In my opinion, Geoff was clearly the best photographer on the Plancius. Geoff certainly put the effort in on the bows. It was good to catch up with Geoff again who I first met on the Pitcairn trip. He could always be relied on to liven up the evenings with some of his stories & jokes. This is Geoff's 'Winter plumage'. The full Bush Tuckerman gear didn't appear until it became warmer
Chris Mills
Phil Hansbro, Chris Gladwin & Chris Mills gassing while waiting for some more Birds to appear
US Birder Ron Hoff
Guess we should have a look at some Birds rather than Birders.
Black-browed Albatross: The Amy Winehouse of Albatrosses
Black-browed Albatross
Black-browed Albatross
One of the tricky identification species is the Wandering Albatross group. Clements treats all Wandering Albatrosses as one species with several very distinct subspecies. However, other authorities split these distinct populations. The safest identification of these Wandering Albatrosses is seeing them around their breeding locations. In the South Atlantic there are two likely subspecies. Snowy Wandering Albatrosses & Tristan Wandering Albatrosses. Snowy Wandering Albatrosses breed on South Georgia, as well as, various Indian Ocean Islands (Prince Edward, Marion, Crozet & Kerguelen) & Macquarie Island (South of New Zealand's Subantarctic Islands). Tristan Wandering Albatrosses breed on Gough Island and the Tristan da Cunha Islands. The other subspecies are Gibson's Wandering Albatrosses & Antipodean Wandering Albatrosses which breed in the New Zealand Subantractic Islands & Amsterdam Wandering Albatross which breed on Amsterdam Island in the Indian Ocean.
Tristan Wandering Albatross: Individual 1 old adult male. Only the oldest adult male Tristan Wandering Albatrosses show this extent of white in the wing
Tristan Wandering Albatrosses apparently have a smaller, slighter & more compact build compared to Snowy Wandering Albatrosses. However, that is something I'm struggling to see comparing these photos with photos taken of Snowy Wandering Albatrosses taken around South Georgia. Plumage-wise Tristan Wandering Albatrosses can exhibit most of the same plumages that Snowy Wandering Albatrosses show, although the whiter individuals are more likely to be Snowy Wandering Albatrosses. Therefore, with only 200-300 nautical miles sailing to Gough Island, it is likely that the Wandering Albatrosses seen today will be Tristan Wandering Albatrosses. All these individuals have been identified on range.
Tristan Wandering Albatross: Individual 2 adult male. A more typical adult male Tristan Wandering Albatross
Tristan Wandering Albatross: Individual 3 old adult male
Tristan Wandering Albatross: Individual 4 old adult male
Tristan Wandering Albatross: Individual 5
Tristan Wandering Albatross: Individual 5
Tristan Wandering Albatross: Individual 6 adult female
Tristan Wandering Albatross: Individual 6 adult female
Now for some easier to identify Seabirds.
Northern Giant Petrel
Northern Giant Petrel
Soft-plumaged Petrel: Going for the vertical Pterodroma look
White-headed Petrel: I only saw two White-headed Petrels on the Odyssey & neither stayed around for more than a brief flypast past the Plancius. Perhaps not surprising as the nearest breeding colonies are the Crozet & Kerguelen Islands in the Indian Ocean & the New Zealand Subantarctic Islands
White-headed Petrel: I like the way it keeps its head vertical despite the rest of the body being vertical
Atlantic Petrel: They only breed on Gough & the Tristan da Cunha Islands & range across the Southern Atlantic
Atlantic Petrel: The medium size, sharply contracting white belly with the dark throat, upper breast, underwings & vent makes Atlantic Petrels a fair easy species to identify
Grey Petrel: Grey Petrels breed throughout the Southern Oceans from Gough & the Tristan da Cunha Islands to the Indian Ocean Marion, Crozet & Kerguelen Islands & some of the New Zealand Subantarctic Islands
Grey Petrel
Grey Petrel
Grey Petrel: These large Petrels are great when you see then close up
Spectacled Petrel: They only breed on Inaccessible Island in the Tristan da Cunha group
Spectacled Petrel: They are a real treat to see
Great Shearwater: It is no surprise that we were starting to see more Great Shearwaters as Gough & the Tristan da Cunha Islands are their main breeding grounds, with smaller numbers breeding on Kidney Island in the Falklands
Great Shearwater: It was great to have prolonged views of this cracking Shearwater close to the Plancius, especially given their rarity in Dorset (only 12-15 records), although they are more regular in the South West of the UK

Great Shearwater
Great Shearwater
Sooty Shearwater
Little Shearwater: The Subantarctic races of Little Shearwater used to be lumped with the North Atlantic Little Shearwaters
Little Shearwater: They are more grey & white, whereas, the North Atlantic Little Shearwaters are black & white
Little Shearwater: They have the same flight action & stiff winged flight as the North Atlantic Little Shearwaters
However, there is a final tricky identification problem to look at: Prions. In the last few years, there has been a new species of Prion found breeding on Gough Island. Originally, it was thought that only Broad-billed Prions breed on Gough Island. However, there is a second breeding Prion as detailed in a paper by Dr Peter Ryan et al in 2014. This paper documents that the second breeding Prion is only 1-2% smaller in the bill, head & wing lengths, but they have a 15% smaller bill width & bluish colouration on the upper mandible. The new Prion resembles the Indian Ocean breeding MacGillvray's Prion. The new Prion breeds about 3 months later than the Broad-billed Prions & there is some separation of breeding locations on Gough Island. Clements treats MacGillivray's Prions as a subspecies of Salvin's Prion. Salvin's Prion is split into the Salvin's subspecies (which breeds on Prince Edward & Crozet Islands) & MacGillivray's Prion (which breeds on St Pauls & Amsterdam Islands). Thus, the previous known range made the Salvin's Prion an Indian Ocean breeder. Assuming the new Gough population are part of the MacGillivray's population, then this would be a major range extension into the Atlantic. Ultimately, it is perhaps more likely that the new Gough Island population could end up being split once all the research has been completed. So it was a case of trying to photograph as many Prions as possible as we approached Gough Island.
Broad-billed Prion: Individual 1. Given that there doesn't seem to be anything on the overall plumage to help separate the two species, then I started by trying to find Prions with very wide bills: this individual appears to have a broad based bill
Broad-billed Prion: Individual 1
Broad-billed Prion: Individual 1
Broad-billed Prion: Individual 2. This has a very dark grey/black & uniform bill
Broad-billed Prion: Individual 2. The base of the bill is very broad making it a Broad-billed Prion
Broad-billed Prion: Individual 2
Broad-billed Prion: Individual 3. Again this seems to have an all dark grey bill which looks pretty heavy so again I'm assuming this is a Broad-billed Prion. However, I don't have any front on views of the bill on this individual
So having tried to find some examples of Broad-billed Prions, I'm looking for examples of Prions that look different to these Broad-billed Prions. Part of the problem is the only reference photos I can find of MacGillvray's Prions at sea are from the Indian Ocean population.
MacGillvray's Prion: Individual 1. This individual appears to have a paler upper mandible (in all photos) & a slimmer bill. Whilst the abstract of Dr Ryan's paper doesn't state if there any differences in bill depth, photos of MacGillvray's Prions from the Indian Ocean populations look less heavy. This is perhaps of limited use given these are at the very least different populations (if not species in the fullness of time). However, given there has been comparison to the MacGillvray's Prion in the abstract, then maybe it's significant
MacGillvray's Prion: Individual 1
MacGillvray's Prion: Individual 1. Again the bill shape & colouration looks consistent
MacGillvray's Prion: Individual 1
MacGillvray's Prion: Individual 2. This individual again appears to have a more uniform paler & slimmer bill that is consistent in all photos
MacGillvray's Prion: Individual 2
MacGillvray's Prion: Individual 2
MacGillvray's Prion: Individual 2
MacGillvray's Prion: Individual 2
At the moment, I've assumed these two individuals are MacGillvray's Prions. I'm sure I will come back to re-examine these photos in coming years as hopefully more at sea photos of the Gough Island MacGillvray's Prions emerge. However, given how difficult it is to reach Gough Island & with this being the last planned Odyssey trip, then there might be few opportunities for others to visit & get photographs. As always, any comments on these Prion photos would be welcome.

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