Vanuatu Petrel - first live sighting?

[Angus Wilson]

I noticed a short note to the letter page of Birdwatch magazine (June
2008 issue) from Steve Wood (New Zealand) drawing attention to a
gadfly petrel he'd photographed in March 2006 near the Kermadec
Islands, New Zealand, that is suggestive of Vanuatu Petrel Pterodroma
occulta. The photo is reproduced on the Wrybill Birding Tours web site
<http://www.wrybill-tours.com/idproblems/pterodroma1.htm>. It is not
clear if there is a series of photographs and whether the bird struck
him as unusual (e.g. small) in the field.

This very poorly known seabird was first described by Imber and
Tennyson in 2001. Six specimens were obtained by the American Museum
of Natural History (AMNH) Whitney South Sea Expedition in January
1927, near the Banks Islands but until more recently, not recognized
as different from the very similar White-necked Petrel P. cervicalis.
In 1983, an additional specimen was taken in northern New South Wales,
Australia.

They are significantly smaller than White-necked and show a more
expansive area of gray on the underside of the primaries and a broader
dark leading edge to the underwing. White-necked Petrels typically
show a less dark underprimaries (e.g. photo (Fig. 15) by Chris Collins
on OceanWanderers <http://www.oceanwanderers.com/WPO.html> taken on
the 2006 WPO recce).

However, a number of seasoned field observers have commented that the
presence of darker primaries is not unique to the smaller form, a
point that is also made from analysis of specimens in the Imber and
Tennyson paper. Indeed, check out this wonderful shot <http://
www.aviceda.org/abid/birdimages.php?action=birdimage&bid=686&fid=56&p=7&pagesize=1>
taken by B Whylie on a Wollongong pelagic in March 2008.

One interesting but tangential point is the repeated occurrence of
pairs of very similar looking seabirds (often found together at sea)
that differ markedly in size (Tahiti/Beck's, Fea's/Zino, Greater/
Lesser Snow Petrel). What's up with that?

Some authors (e.g. Michael Brooke 2004) treat Vanuatu and White-necked
as conspecific, at least until more is known, but the split has been
acknowledged in the new Australian Checklist (Christidis and Boles
2008). An alternative name in the literature is Falla's Petrel in
honor of the renowned ornithologist Sir Robert Alexander Falla.
Obviously, seabirders in Australia and New Zealand are looking
carefully at 'White-necked/Vanuatu' Petrels and I imagine more
information will emerge, especially from birders visiting the waters
around the Vanuatu islands. A dedicated chumming expedition, mirroring
Hadoram Shirihai's rediscovery of Beck's Petrel in the Bismark
Archipelago off Papua New Guinea, may be highly rewarding. I've seen
it rumored on the web that Hadoram has photographed candidate
Vanuatu's Petrels but have no other information. Perhaps he can chime
in here?

The location of Wood's new sighting seems puzzling. The Kermadec
Islands (specifically Macauley Island) are the world stronghold for
White-necked Petrel with 50,000 nesting pairs, and relatively distant
from the locations of the Vanuatuan and Australian specimens. Onley
and Scofield (2007) speculate that the birds might breed on Mera Lava
(where the types were collected in 1927) and other islands in the
northern part of the Vanuatu archipelago. Mere Lava (sometimes spelled
Mera Lava) is a small volcanic island 52 km southeast of Gaua in the
Banks Group (-14.4629°, 168.042°).

Literature Citations:

Christidis, L. and Walter E Boles (2008) Systematics and Taxonomy of
Australian Birds. CSIRO Publishing.

Imber, M. J. and A.J.D. Tennyson (2001) A new petrel species
(Procellariidae) from the south-west Pacific. Emu 101 (2): 123-127.

Wood, S. (2008) Another 'lost' petrel found? Birdwatch June 2008 Issue
192, p21.

Cheers, Angus Wilson
New York City, USA
http://oceanwanderersnews.blogspot.com/
http://oceanwanderersnews.blogspot.com/
http://www.oceanwanderers.com/

[Ross Wanless (Cape Town Pelagics)]

Hi Angus et al
A quick google search failed to reveal any information about Mere/Mera
Lava, and specifically about invasive species there. The probability
of an active colony is going to be much higher in the absence of cats,
pigs or rodents. This might make searches for likely islands a bit
more efficient.
Cheers
Ross

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[Angus Wilson]

Hadoram Shirihai has provided the following informative commentary:

Re: the short note by Steve Wood/Dominic Mitchell in Birdwatch and
Angus Wilson on Seabird-News.

www.wrybill-tours.com/idproblems/pterodroma1.htm

Dear Friends,

It is correct that I initially speculated (as Michael Imber probably
did too, per the note in Birdwatch) that the petrel photographed by
Steve Wood could be the poorly-known Vanuatu Petrel Pterodroma
occulta. However, this was done before I had an opportunity to
experience the two forms at sea and around the breeding grounds (i.e.
White-necked Petrel Pterodroma cervicalis in the Kermadec Islands, and
Vanuatu Petrel around Vanuatu), and also prior to examining the 6
specimens of occulta at the AMNH. In the future, I will be happy to
share the results of these studies with others but not in this short
response.

As it happens I sent to Steve Wood an email some time a go to say that
Vincent Bretagnolle and I both think that the photographed petrel is
NOT an occulta nor is it a cervicalis. Instead, we thought that it
could be a member of the Collared/Gould's Petrel Pterodroma brevipes/
leucoptera complex, but oddly enough with an underwing pattern and
overall shape reminiscent of Black-Winged Petrel. However, the black
on the head/cap looks too extensive for the latter. The apparent white
collar is not conclusive, as this could possibly be an effect of wear.
In fact, from this single photo taken at this angle, Steve Wood's
petrel shows a combination of underwing, head and neck patterns that
to my eyes (at least superficially) resembles the Atlantic's Black-
capped Petrel Pterodroma hasitata, but it is impossible to know from
this single image if it has white rump/upper-tail coverts as it should
have for hasitata.

Now after experiencing the entire Pacific's Pterodroma taxa I can say
that Steve Wood's bird has an odd combination of features that do not
quite fit any one species. There seem to be four main possibilities
(all are of equally possible, and other possibilities are welcome
too): 1. that some of the odd characters are attributed to a
'photographic-trick' due to the angle of view, light conditions and
partial wear/bleaching. 2. that the bird is a hybrid. 3. a vagrant
petrel from another ocean, e.g. Black-capped Petrel (but don’t jump on
me with a knife, I am simply suggesting that it superficially
resembles that species from this angle, nothing more!!). 4. It is a
completely new and undescribed species of petrel.

There is probably not much point in discussing the identity of this
bird further until more examples are found, although I believe no one
else has ever seen and/or photographed a similar petrel in the
Pacific. We have to accept that some birds/images cannot be identified
to a specific taxon, and thus should left unidentified. For me at
least, Steve Wood's bird should remain as an unidentified Pterodroma.

As to Vanuatu Petrel, I feel, as with the rediscovery of the Beck's,
that I should play safe here - i.e. follow a deliberate and careful
approach and progress with the birds I am trying to identify at sea.
And, yes I have tentatively identified Pterodroma occulta at sea in
south Vanuatu, but would prefer not to publish my records until I gain
further evidence and photos. I thank you for respecting this wish.

In relation to our book 'Albatrosses, petrels and shearwaters of the
world: a handbook to their taxonomy, identification, ecology and
conservation’, co-authored with Vincent Bretagnolle and illustrated by
John Cox, for A & C Black, London', Vincent and I are planning major
expeditions to Vanuatu, and we will be more than happy to share our
findings with others.

I would like to add here that we are still have one extra space for
the 'Fiji Petrel At Sea Expedition’. So far, only Tony Pym and Brent
Stephenson showed interest in joining Dick Watling and I.

Thanks for your 'tubenose friendships'

Hadoram Shirihai
albatross...@hotmail.com

[Angus Wilson]

Hadoram Shirihai has provided a more detailed analysis of the
mysterious petrel photographed by Steve Wood at sea off the Kermadec
Islands in New Zealand. To read his commentary and view two
instructive photos by Tony Quinn please visit the "Picking from the
Chum Slick" blog.

http://oceanwanderersnews.blogspot.com/

Cheers, Angus Wilson
New York, USA