Wednesday, 29 August 2012

Tuamotu Sandpiper — a Morning Encounter with an Endangered and Strange Bird

There are some species of birds that have the appearance and behaviour of having been designed by a committee of civil servants. The mesites of Madagascar constitute one such example. However, there is another.

The Tuamotu Sandpiper (Prosobonia cancellata) now occurs on only a few atolls in French Polynesia and is classified as Endangered. Rats, cats and human expansion have taken their toll and only five atolls now have a population according to the latest reports by Birdlife International.

A sighting of this species is highly desirable to the ‘World Lister’, that curious breed of bird watcher (bird ticker is a better term) that attempts to see as many species as possible, often, unfortunately, with little or no understanding of what they are seeing. Hard-core bird ticker trips usually head at very great expense for Tenararo, in the Actaeon group of the Tuamotus, where sightings of the bird are the most reliable.

The first time we went to Tahanea atoll in 2009, nobody on board Clipper Odyssey knew it was worth looking for the Tuamotu Sandpiper. Had they done done so, Brent Stephenson, the ornithologist on board this Noble Caledonia expedition cruise, would not have let the opportunity pass us by. Tahanea is a drop-dead gorgeous, straight out of south sea island tourist brochure, atoll. The ship enters the lagoon through a gap between the motus — the islets that surround the lagoon. Zodiacs set off to explore the motus and for snorkelling. An excellent morning. We were not disappointed when, the next year, in 2010, we saw that on another Noble Caledonia expedition cruise from Easter Island, via Pitcairn, to Tahiiti, we were to visit Tahanea again. This time word had got out that there were Tuamotu Sandpipers on a rat-free motu and there was research in progress on this species. On the outward voyage from Tahiti to Easter Island, Clipper Odyssey was carrying a Zegrahm Expeditions cruise. They had visited Tahanea and seen the beast. This time Simon Boyes was ornithologist on board for Noble Caledonia and he had a rough map showing which motu was the one to visit. As soon as the ship was anchored in the lagoon, the expedition team set off to find the landing place. We followed in Zodiacs across the large lagoon (Tahanea is a large atoll, 48 km long and 15 km wide). Those interested in seeing the bird split up to explore an area of scrub bounded by the beach and by a depression in the coral part-filled by water. Simon thought he had seen the bird flittering upwards soon after he arrived as part of the scouting party. I scanned the side of the depression and saw  a small brown wader running across and going into the scrub. Just enough of a look to say it was the sandpiper but not enough to get the others on to it. We managed to signal to Simon and party coming from the other side and both these groups moved to meet in the middle. As we met, the third group flushed the bird from where I had seen it running and it flew into a tree where it clambered about like a passeriform rather than a wader. I tried to get some video footage but it was really out of range of my camera and my ability to hold the camera sufficiently still at full zoom. I did get some footage but it was too shaky to be of much use. Then Maggie, who had flushed the bird and who had the lens with the longest focal length, went forward as far as possible and took the shot you see below. As I was trying for more video, the bird clambered along the branches for a short time and then flew with its strange flittering flight into the scrub again. As we returned in the Zodiacs across the lagoon to the ship (the Zodiac drivers clocked more than 100 miles that day), we realised we had seen not only a very rare bird but also a very unusual one, and what turned out to be an even more unusual than we then thought.

Maggie's photograph of the Tuamotu Sandpiper

Since returning to UK I have been keeping an eye on reports of research on this species in Tahanea and elsewhere, while also wondering what this bird’s salt gland would be doing in this habitat.

Marie-Hélène Burle, an MSc student at Simon Fraser University in British Columbia, has done the work and links to websites showing research reports are shown below. She spent 5 months in the austral summer of 2008-2009 on Tahanea, with another 4½  months in the austral winter from May 2011. In that time she has made what I would consider remarkable progress in understanding this bird and its habitat on 27 motus of the atoll and I look forward to reading the papers that will emerge. I will only draw attention to two aspects here.

We knew that the bird is an unusual member of the Scolopacidae. It does not frequent beaches and mud but low vegetation. It has a short bill and legs. It has short, rounded wings which give it the characteristic flittering flight. It perches and moves amongst the branches in trees. But what we did not know is that the bird is, as Marie-Hélène Burle discovered, a nectar feeder. Of course, it takes any small organisms that it finds but a nectar-feeding wader takes the my prize for adaptation this year. The work begun on the structure of the tongue (an unusual shape) that Marie-Hélène Burle has started should prove informative.

She also exterminated the rats on one motu to investigate the effects on the bird and observed a crash in the population in 2011 (55% of the birds died within a month on Tahanea) after an overwash from an unusually strong swell. On her third visit (detailed in her report linked below) she plans to study breeding success after this perturbation as well as to follow up the results of the rat eradication.

I am filled with admiration for the dedication lone workers who spend months in the field. I think Marie-Hélène Burle (and the organisations who have supported her financially and organisationally) has done and is doing a great job in finding not only far more about this species than anybody has done in the past but also pointing the way to the key requirements for its conservation. I cannot help but comment that as an MSc student she could point out that PhDs have been awarded for far less.

So we not only saw a very unusual wader during our morning in Tahanea but a nectar-feeding wader. And yes, I did chant out loud, as the outboard motor propelled us as maximum revs to the ship, the last sentence in the Origin of Species — the one beginning, There is grandeur in this view of life...

Tahanea - showing the scrubby vegetation to the right where the Tuamotu Sandpiper was found; the lagoon is on the left.


Birdlife International - Tuamotu Sandpiper

Reports and Press Reports on Marie-Hélène Burle's Research

Brent Stephenson's Blog

Simon Boyes's Website

Noble Caledonia Website