'New Caledonian Storm-petrel'
In many respects this has been the most interesting (and sometimes frustrating) birding conundrum I have ever been involved with. The following text is adapted from a short article I wrote for Birding World magazine (published in July 2013) although a wider range of photos are included here than in the magazine article.
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During the 2008 West Pacific Odyssey cruise, a strange black-and-white storm-petrel was seen approximately 25 nautical miles off the coast of southern New Caledonia. In a short article which was published in Birding World a couple of months later, Steve Howell and I described how the bird resembled New Zealand Storm-petrel Fregetta (formerly Oceanites) maoriana, a species which had been rediscovered less than four years earlier in the Hauraki Gulf, off North Island, New Zealand (Flood 2003). We noted, however, that the bird seen off New Caledonia appeared rather large for this species and suggested that an alternative possibility was that it could be an undescribed, but closely related, species.
Whilst this might seem rather unlikely, there are a surprising number of examples in the Pacific of almost identically plumaged seabirds where size is the main difference and with birds such as Beck’s Petrel Pseudobulweria becki (Pym 2008 and Shirihai 2008), Fiji Petrel Pseudobulweria macgillivrayi (Shirihai et al 2009) and Vanuatu Petrel Pterodroma occulta (Imber 2001 and Totterman 2009) all having been discovered, or rediscovered, in recent years, the possibility that other unknown seabirds could exist was more likely than some birders might have supposed.
The mystery storm-petrel was not seen in 2009 (due to the voyage following a slightly different itinerary), but in 2010 and 2011, it was found at approximately the same location as in 2008. Although somewhat distant on both occasions, the bird was seen on the same fish oil slick as one or more Wilson’s Storm-petrels Oceanites oceanicus and the views reinforced the impression from 2008 that it was larger than a Wilson’s Storm-petrel. Despite the published measurements for New Zealand Storm-petrel (Onley and Scofield 2007) suggesting this species should be smaller than Wilson’s Storm-petrel, it remained difficult to believe we really were looking at an undescribed taxon.
Finally in April 2012, at least one of the mystery storm-petrels was seen well on a seamount off the south-east corner of New Caledonia and after four years of frustrating views, it did seem that there were a number of subtle, but distinct, differences from New Zealand Storm-petrel. For example, the bird appeared to have broader wings, a different underwing pattern (with more restricted amounts of white compared with New Zealand Storm-petrel) and was far more heavily streaked on the breast than any New Zealand Storm-petrel any of us had ever seen in the Hauraki Gulf.
Indeed, with the internationally renowned seabirder, Peter Harrison, onboard and suggesting that the bird also had a different foraging behaviour from New Zealand Storm-petrel, it seemed that we were indeed looking at something which wasn’t covered in the seabird literature.
The 2012 sighting also raised the interesting prospect that the birds off New Caledonia could possibly be the long lost ‘Lined Storm-petrel’ Pealea lineata which was collected in the middle of the 19th Century in Samoa and had lain largely ignored in a museum drawer ever since. Although only known from a single specimen, this bird was also black-and-white with extensive streaking on the underparts and was, therefore, a close match to the New Caledonian birds.
New Caledonian Storm-petrel (2012): in the left photo, the closer bird is a Wilson's Storm-petrel and it appears distinctively smaller than the NCSP. In the right photo, the heavy streaking (which is consistently thicker than on a New Zealand Storm-petrel) is apparent.
Spurred on by the views in early April 2012, Aaron Russ and I decided to organise an expedition to New Caledonia, with the goal of catching at least one of the storm-petrels and taking blood and feather samples for DNA analysis. Despite having recorded the bird over four separate years, we had never seen more than one individual on any of our chum slicks, so both of us were adamant that no specimens would be taken and any birds which were caught would be released. It was, after all, difficult to envisage the bird being categorised as anything other than ‘critically endangered’, so we had no intention of following some recent US expeditions which have taken more than a dozen specimens of new species to science, before having any real concept as to how common the birds they have discovered actually were.
A year later and with the necessary funding and permits secured, an international team assembled in Noumea and on 16 March 2013, we set sail on a specially chartered catamaran with food for a week and over 60 litres of fish oil !!!
The waters off New Caledonia can be highly productive for tropical seabirds and on our first afternoon, the species seen included White-necked Petrel Pterodroma cervicalis, Gould’s Petrel Pterodroma leucoptera, Black-winged Petrel Pterodroma nigripennis, Tahiti Petrel Pseudobulweria rostrata as well as Wedge-tailed Shearwater Puffinus pacificus, Red-footed Booby Sula sula and Black-naped Tern Sterna sumatrana. Whilst a minimum of five Wilson’s Storm-petrels also visited our fish oil slicks, no ‘New Caledonian Storm-petrels’ were seen.
The following morning, however, our luck changed and after watching a slick for two hours, one of the mystery birds was spotted. Our net gun was rapidly assembled and a few minutes later, the catamaran’s small inflatable rib was launched. With swells of two metres, it was a challenge to keep track of the storm-petrel, as it would move rapidly around the slick and then disappear, before returning to the oil. After what seemed like an eternity, it finally flew directly towards us and the net gun was fired. With a brisk wind in our faces, unfortunately, the net did not carry far enough and with a sinking feeling, we knew we had missed our target by a whisker.
New Caledonian Storm-petrel (March 2013): both shots show the heavy streaking which is typical of this bird
Over the next few days, we chummed in a variety of water depths elsewhere along the southern coast of New Caledonia but had no success in locating the storm-petrel, so on 21 March returned to the area where we had initially found it. With the winds blowing at up to 20 knots, conditions were far from ideal and when one of the storm-petrels showed up and proceeded to spend over an hour on the chum, we were in the frustrating position of getting close views, but the weather meant it was impossible to contemplate catching it. Has birding ever been more frustrating !!!!
New Caledonian Storm-petrel (2013): more shots from the 2013 New Caledonian seabird expedition. One point to note in the top right photo is the restricted amount of white on the underwing. A New Zealand Storm-petrel would show more white.
Despite the conditions, the five photographers in the team were able to get plenty of images of the bird and whilst our return to Noumea was tinged with the disappointment of not achieving our principle goal, the new photos added important insights to what we had learnt in 2012; there now seemed to be no question that the bird had a different jizz to New Zealand Storm-petrel with proportionately longer wings, body and tail, as well as the plumage differences noted above.
A couple of weeks later, Peter Harrison led another expedition to the region but like us, his team’s attempts to catch the bird were close but, ultimately, unsuccessful. They too, however, had some excellent opportunities to study and photograph it and to quote Peter: “I believe that when this story is eventually played out, you will find that New Caledonian Storm-petrel is actually Pealea lineata and that New Caledonian Storm-petrel and New Zealand Storm-petrel are two closely related taxa that have adapted to different latitudes. Amazingly both have been resurrected at about the same time, birds that have truly returned from the dead !!”.
So whilst the mystery is yet to be resolved (and yes Aaron and I are planning to return to these waters in 2014), it really does seem possible that a bird that has not been seen for over 170 years has indeed been surviving in an isolated corner of the Pacific. We can only speculate as to what else remains to be discovered............
New Caledonian Storm-petrel (2013): more shots from the 2013 New Caledonian seabird expedition.
New Zealand Storm-petrel, Hauraki Gulf, New Zealand: note the subtly different jizz to NCSP, the more extensive white on the underwing and the finer streaks on the breast.