ShareThis22 October 2010
About 100 nautical miles west of Darwin over Flat Top Bank, we encountered the first of several groups of small to medium-sized shearwaters. The six birds initially seen were in heavily overcast conditions and because they appeared dark, were called as Hutton’s Shearwaters.
A montage of images from a flock of about 35 birds seen off Darwin during the Peregrine Bird Tours Ashmore Reef trip 2010. Photos by Simon Mustoe.
However, photographs confirmed we were in fact looking at one of the ‘Audubon’s’ type shearwaters. We’ve long expected such a seabird to occur in Australia but had no idea they would be in such big numbers.
In the end, we saw seven groups, the largest of which comprised about 35 birds. So this would appear to be not only a first for Australia but also a substantial wintering ground. Evidence currently available to us points to these being Arabian Shearwater, a bird that breeds in the far north west Indian Ocean.
A flock of about 35 shearwaters, thought to be Arabian Shearwaters
Arabian Shearwater and Galapagos Shearwater Puffinus subalaris are the only species in the Audubon’s complex that have a substantially dark underwing, wedge-shaped tail, lack of white rump-sides and pink legs. The birds off Darwin couldn’t be Galapagos Shearwater because that species breeds year-round in the eastern Pacific and is largely sedentary. By contrast, Arabian Shearwater breeds from May to September in the vicinity of the Arabian Sea but also possibly in other unknown parts of the northern Indian Ocean.
The field characters that identify these birds as Arabian Shearwater are:
- Heavily marked dark underwing.
- Medium-sized with relatively long pointed wings.
- Long wedge-shaped tail.
- Pinkish legs almost reaching tail tip.
- Dark undertail coverts and black wedge on side of rump.
- Total lack of any white patches on the rump sides.
- Dark cap extending to just below eye.
- White eye ring.
- Long slender, bluish bill with dark tip.
Comparison to Other Species
Hutton’s Shearwater – the birds cannot be Hutton’s Shearwaters because they lack a broad dark cheek patch; the feet do not extend well beyond the tail; the undertail area is dark, not white; and they have a distinct eye-ring and narrow head.
Fluttering Shearwater - the dark markings under the wing are far too extensive and they have a distinct eye-ring. The shape of the dark hood is wrong (the demarcation between dark and pale is too straight between eye and wing base); the undertail is dark rather than white; and the rump lacks any distinct white patches on its sides.
Little Shearwater – the bird does not resemble any of the races of Little Shearwater. The bill is too long; the underwing markings are far too extensive; the wings are too long and the flight style was too lazy. The dark hood extends too far below the eye; and the rump lacks any distinct white patches on the flank-margins.
Tropical Shearwater – the bird does not look like Tropical Shearwater because, the rump lacks any distinct white patches on the flank-margins; the legs are pinkish (not blue); the base colour of the birds’ plumage is brown, not blackish; the dark hood extends too far below the eye and is too demarcated from the pale throat.
[...] It takes almost three days to reach Ashmore but our excitement began not far out of Darwin where we crossed one of the richest, but surprisingly, least known areas of ocean in the world. Where else could we find a wintering seabird never before recorded in Australia. It’s a type of ‘Audubon’s’ shearwater, now considered several distinct species. Our bird is most likely Arabian Shearwater Puffinus persicus all the way from the Gulf of Oman (READ MORE). [...]
Far out! I thought my getting Giant Pitta male in Borneo was good too!
Well done. Spectacular find. The number of birds I think suggest that this may not be an fluke sighting as well.
The current consensus is that these are indeed Arabian (or Persian) Shearwater. This is a very significant discovery for Australia, adding a new wintering seabird species to the list.
Congratulations Simon. What a great discovery and I hope it is new taxa.
You might find the following anecdote of use on your next trip
From 1993 to 1999 Pat and I were Kimberley commercial fishers (Beche de mer and Spanish Mackerel) where we lived at sea for most of the year. About every 6 weeks we would sail to Darwin to unload our catch and refuel.
Returning from Darwin our route to the Kimberley would take us via Charles Point and Fish Reef and then up to 100Nm off shore across the Boneaparte Gulf on what we knew as Route 222 (222Nm) on a bearing of approx 250 mag. from Fish Reef to Cape Londonderry. Interestingly this course runs approximately 30 Nm south of Flat Top Bank where you have found the “Arabian Shearwaters”
Anyway, particularly during the dry season, the Boneapart Gulf (known by local sailors as the Blownapart Gulf) is barren regarding pelagic birdlife although occasionally we did see some interesting stuff. But usually in about the third week of October the Gulf comes alive with birds as tuna schools move in. Almost overnight Shearwater flocks often comprising many hundreds of birds appear. They seem to be attracted to the fish schools when they regularly irrupt into a surface feeding frenzy.
The species composition of the shearwater flocks were usually mixed comprising Streaked (about 25%) and making up the bulk of numbers, what I had always thought until your find, to be Hutton’s Shearwater. Numerous terns, mainly Lesser Crested, Bridled and Roseate are often picking around the margins and occasionally I would see all dark medium sized petrels, probably Bulwer’s and large dark storm petrels probably Matsudaira’s as well
When we first observed this in 1993, I was excited about Streaked Shearwaters because at the time they were thought to be rare in Australian waters. This was before digital cameras, the internet, modern pelagic field guides and of course birding-aus and I never questioned the Hutton’s ID as they were common and seen through the wet season although most conspicuos prior to the monsoon when the sea is usually calm.
Another fantastic sight at this time of year coincides with the first full moon of November. The deep sea coral and much of the benthic biota spawns.
It produces a dense cover of what looks like an oily curry powder across the sea This phenomenon is often misreported as oil spill. The fish, the birds, the sea snakes and the crustaceans, everything goes mad. If you get an oily calm night, turn on the deck lights and chase the radar targets. You will see a spectacle that almost defies description.
The shearwater flocks are conspicuous and sometimes large. We would locate flocks from up to 5 Nm using conventional 4Kw marine radar. In November many flocks would be encountered on a single voyage seen anywhere from about 30nm WSW of fish reef to a point near Lesueur Island about 17 Nm ESE of Cape Londonderry, anywhere the blue water occurs.
However from November, the calm seas are often interrupted by violent tropical revolving storms with 50 knot squalls and plenty of lightening. An exciting experience at night these storms are are short lived and don’t stir up sea conditions too much. They are definitely a spectacular sight but when the monsoon hits, that’s a very different story with prevailing gale force NWwinds with each surge lasting sometimes for weeks.
In December 1998 a severe Cat 5 cyclone (Cyclone Thelma) crossed the Boneaparte gulf
see http://en.wikipedia.org/wiki/Cyclone_Thelma and http://www.bom.gov.au/info/cyclone/thelma/track.shtml
and we crossed only 1 week after. The cyclone had stirred the bottom with a force that can hardly be imagined and the water had turned to pale milk colour. There were hundreds of dead shearwaters of both species scattered across the sea. The depth across much of the boneaparte is about 40 fathoms but where the track crosses the WA/NT border it shallows for some distance. There is probably deep sea coral here because after the cyclone, dense mats of kelp floated to the surface and many dead shearwaters were tangled amongst it.
It is a very exciting place to be at this time of year and I wish I was there. Congratulations on a great discovery.
Regards
Ian and Patricia May
St Helens, Tasmania.
Simon, this is great news!
I am certain that these birds are identical to the birds I observed south of the Houtman Abrolhos islands, 80NM west of the mainland, on April 2nd, 1996 from the Jodi Anne II. At the time I identified them as an Indian Ocean form of Audubon’s Shearwater, as distinct from those I was familiar with from the Atlantic and Pacific basins. The birds were foraging amidst a huge feeding flock of Lesser Noddys and it was not possible to be sure of how many there were because they were diving in among the Noddys. My best guess was 8 to 10 individuals. The similarity to Fluttering and Hutton’s Shearwaters was discussed at the time by those on board who thought I had lost my marbles.
Congratulations on obtaining such great images and clinching their identification as something new at least. Obviously from my earlier experience of these birds in Australian waters I concur with the notion that this species has the potential to be a regular visitor, at the very least.
This discovery has hit a bit of a taxonomic sore spot once again. I am happy to go along with persicus but I am not familiar with nicolae. Since, nicolae is often subsumed into dichrous I presume the underwings are not so dark as in these Australian birds and, indeed, persicus. Tropical Shearwater is still a grab bag of several species (forms if one prefers) so it would be dangerous to genralise about what they look like. I have seen several with pink legs, differing in behaviour and base colour (which ranges from brownish to blackish) but all showed distinct “saddle bags” typical of Audubon’s type shearwaters. I would argue strongly with anyone that wanted to include these Australian birds into the Tropical Shearwater grab bag.
regards from the land-locked Capital
Milburn
Hi Simon
A good find for Australia. Not familiar with this taxa but I can confirm its not Hutton’s shearwater or Fluttering shearwater which I am very familiar. Hutton’s have a dark hooded head appearance with an extensive neck collar. The head shape also looks more solid than your birds. Hutton’s also have quite long wings which are narrower than your birds. The underwing coverts are much darker than your birds. Fluttering shearwaters have slightly shorter wings than Hutton’s but are still narrower than the birds in the photos. The tails of both Hutton’s and fluttering shearwaters are relatively short and the legs extend past the tail in flight. These birds have more of the little shearwater type jizz with broader rounded wings and a relatively small head. But the longer tail length and other features that you point out exclude them from that group.
Cheers
Graeme
Hello all,
This is a fascinating discovery. I have had very good looks at Persian Shearwaters off the south coast of Oman at this time of year on several occasions, including close observations of birds at sea. While I can see considerable similarity between the Omani birds and the birds in your photographs, I can also see some very significant differences in underwing pattern, upperwing pattern and moult. I have some very good photographs which I’d be happy to make available to you. To whom should I send these?
Killian Mullarney
Ireland
I have photos from Yemen and Socotra. Who would like to see them?
Richard, I would love to see them. Can you email them to info@bird-o.com? We might do a follow-up article. Killian Mullarney had wanted to make some remarks and I need to follow up with him. Your pictures may help. Is this Richard Porter from RSPB? I (Simon Mustoe) run the site … assuming you are that person, we would have met years ago. Thanks for your kind offer and interest. Simon.