A Spectacled Petrel calls from outside its burrow on Inaccessible Island

NOTE:  This post continues an occasional series that features photographs of the 31 ACAP-listed species, along with information from and about their photographers.  Here, Peter Ryan, Director of the University of Cape Town’s FitzPatrick Institute of African Ornithology, writes about the population research he has conducted over a span of three decades on the Vulnerable Spectacled Petrel Procellaria conspicillata, endemic to the South Atlantic’s Inaccessible Island.  Professor Ryan’s account completes photo essays for the five members of the genus, all of which are ACAP listed.  Access accounts for all the species covered so far in the series in the Photo Essays section on this website.

Peter Ryan weighs a Vulnerable Inaccessible Finch Nesospiza acunhae on Inaccessible Island in 2018; photograph by Ben Dilley

I am often asked what is my favourite bird.  I don’t have an answer; there are so many cool birds that it’s impossible to pick just one.  One contender for the title is the Spectacled Petrel, although in truth, this is coloured as much by my fondness for Inaccessible Island, its sole breeding site, as it is for the bird itself.

A Spectacled Petrel at sea, known as a ‘Ringeye’ to Tristan Islanders

I have been extremely privileged to visit many seabird breeding islands, but the island where I have spent most time is Inaccessible, the larger of the two uninhabited islands in the Tristan archipelago. I first visited Inaccessible for a few hours in 1984, and at the time didn’t think that I would ever get back there.  I was landed by helicopter at Blenden Hall, near the west point of the island, far from where Spectacled Petrels breed on the island plateau.  It was only in 1987, when I returned for a few weeks to study the metabolic rate of the endemic and Vulnerable Inaccessible Island Rail Laterallus rogersi, the world’s smallest surviving flightless bird, that I finally got to see a Spectacled Petrel at its nest burrow.

Out in the daytime: a Spectacled Petrel at its burrow entrance

I returned to Inaccessible the following two years, culminating in a summer-long stay while conducting the research for my PhD on the ecology and evolution of Tristan’s Nesospiza finches, or buntings as they were known then.  However, with assistance from Coleen Moloney, I also made observations on Spectacled Petrels, including recording their calls, and testing their response to playback of White-chinned Petrel P. aequinoctialis calls.  This culminated in a paper splitting the two species, a decision that was later supported with genetic evidence by Mareile Techow.  This is the only time that I have seen Spectacled Petrel chicks – large bundles of down already bearing the distinctive white spectacle that they bear throughout their lives.

Flying in unison: a White-chinned (left) and a Spectacled Petrel

I managed to spend another summer on Inaccessible in 1999/2000.  My main goal was to assess whether there had been any change in the distribution and abundance of hybrid finches on the island plateau in the decade since my PhD study.  But to help fund the visit, I obtained a grant to reassess the population size of Spectacled Petrels.  This was when concern about the impact of long-line bycatch on albatrosses and large petrels was at its peak, and there was real concern about the status of the petrel, given its modest population size and known mortality on long-lines off Brazil.  At that time, the most recent population assessment was Mike Fraser’s estimate of 1000 pairs, made during the Denstone Expedition to Inaccessible in 1982.  To our surprise, we found that there were at least 4000 occupied burrows on the island.  Either Mike’s estimate was very conservative, or the species was doing well despite the impacts of long-line bycatch.

With no introduced cats or rodents, Spectacled Petrels can breed undisturbed

I returned in 2004 with Cliff Dorse to repeat the Spectacled Petrel survey.  We estimated a population of some 10 000 pairs, and further surveys in 2009 (with Rob Ronconi) and in 2018 (with Ben Dilley) confirmed that the population was increasing in leaps and bounds, with the most recent estimate as high as 30 000 pairs.  It appears that the Spectacled Petrel narrowly avoided extinction at the end of the 19th Century, when feral pigs roamed Inaccessible Island.  Fortunately, the pigs died out before they ate the last of the petrels, and the Spectacled Petrel population has been recovering ever since.  As a consequence, the species’ threatened status was moved from Critically Endangered to Vulnerable in 2007.  It is likely that a sister population used to breed at Amsterdam and perhaps also on St Paul, French islands in the central Indian Ocean, but were extirpated by the menagerie of mammals introduced to those islands.

A Spectacled Petrel glides over Bog Ferns Blechnum palmiforme on Inaccessible Island at dusk
Photographs by Peter Ryan

Inaccessible Island is now formally protected as a Nature Reserve, and forms part of the Gough and Inaccessible Islands World Heritage Site.  I applaud the foresight of the Tristan community for conserving these magnificent islands and their globally important biota.

Selected Publications:

Fraser, M.W., P.G. Ryan & B.P. Watkins 1988.  The seabirds of Inaccessible Island, South Atlantic Ocean.  Marine Ornithology  16: 7-33.

Reid, T.A., Ronconi, R.A., Cuthbert, R.J. & Ryan, P.G. 2014.  The summer foraging ranges of adult Spectacled Petrels Procellaria conspicillata.  Antarctic Science 26: 23-32.  [click here].

Ryan, P.G. 1998.  The taxonomic and conservation status of the Spectacled Petrel Procellaria conspicillata.  Bird Conservation International  8: 223-235.

Ryan, P.G. & Moloney, C.L. 2000.  The status of Spectacled Petrels Procellaria conspicillata and other seabirds at Inaccessible Island.  Marine Ornithology  28: 93-100.

Ryan, P.G. & Ronconi, R. 2011.  Continued increase in numbers of spectacled petrels Procellaria conspicillata.  Antarctic Science 23: 332-336.  [click here].

Ryan, P.G., Dilley, B.J. & Ronconi, R.A. 2019.  Population trends of Spectacled Petrels Procellaria conspicillata and other seabirds at Inaccessible Island.  Marine Ornithology 47: 257-265.  [click here].

Ryan, P.G., Dorse, C. & Hilton, G.M. 2006.  The conservation status of the Spectacled Petrel Procellaria conspicillata.  Biological Conservation 131: 575-583.

Techow, N.M.S.M., Ryan, P.G. & O'Ryan, C. 2009.  Phylogeography and taxonomy of White-chinned and Spectacled Petrels.  Molecular Phylogenetics and Evolution  52: 25-33.  [click here].

Peter Ryan, FitzPatrick Institute of African Ornithology, University of Cape Town, 22 October 2021

In support of last year’s World Albatross Day on 19 June ACAP released three infographics for the Critically Endangered Tristan Diomedea dabbenena and Waved Phoebastria irrorata Albatrosses and for the Vulnerable Wandering Albatross D. exulans.  The last species was co-published with the NGO, BirdLife South Africa.  All three infographics were designed and illustrated by Namasri ‘Namo’ Niumim.

The vision of ACAP is, in time, to produce infographics for all 31 ACAP-listed species; efforts are currently being directed at producing infographics for the 22 species of albatrosses, primarily in support of future World Albatross Days.  The fourth in the series, again illustrated by Namo Niumim, is of the globally Endangered and Nationally Critical Antipodean Albatross Diomedea antipodensis.  This species, endemic to New Zealand, is co-published by that country’s Department of Conservation, which has covered the costs of its production.  The new infographic refers to the threats the Antipodean Albatross continues to face, notably from interactions at sea with fishing vessels which disproportionally kills females (as illustrated in a recent news article).

Voting in New Zealand’s Te Manu Rongonui o te Tau/Bird of the Year (BOTY) competition for 2021 is now open and continues until month end, with the Antipodean Albatross on the list (click here).  ACAP’s and DOC’s infographic helps explain why the Antipodean Albatross would be a deserving winner this year, following its second place in BOTY2020 last year.

English language versions of infographics, including those featuring the three previous albatrosses, are available to download here, whilst French and Spanish versions can be found in their respective language menus for the website under, Infographies sur les espèces and Infographía sobres las especies. 

With thanks to Namasri Niumim for her artistic work, and to Ian Angus, Igor Debski and Johannes Fischer of the New Zealand Department of Conservation, for their valued inputs.

John Cooper, ACAP Information Officer, 21 October 2021

 White-chinned Petrel, Fairchild’s Garden, Adams Island, Auckland Islands, December 2015

NOTE:  This post continues an occasional series that features photographs of the 31 ACAP-listed species, along with information from and about their photographers.  Here, Kalinka Rexer-Huber, of the New Zealand-based environmental consultancy Parker Conservation describes the research she has conducted on the globally Vulnerable White-chinned Petrel Procellaria aequinoctialis.

Kalinka Rexer-Huber holds a White-chinned Petrel under permit on Adams Island preparatory to fitting a tracking device; photograph by Graham Parker

White-chinned Petrels hold a special fascination for me.  I first met them south of New Zealand, flying around effortlessly across an ocean that threw seas over the ship.  Then I encountered them on islets in the Falkland Islands/Islas Malvinas* - a small handful of burrows that felt like discovering buried treasure.  I was happy to find White-chinned Petrels abundant on South Georgia/Islas Georgias del Sur*, liberally spread out in colonies noisy with chatter and display.  But petrels were not on my dance card, so my interest had to wait.  Meanwhile there were more ships enabling at-sea surveys of various kinds in the Falklands/Isla Malvinas*and back in New Zealand with more White-chinned Petrels to be recorded.  I was alarmed to learn then that this burrowing petrel is the seabird species most caught as bycatch by fisheries in the Southern Hemisphere.

A White-chinned Petrel flies past the cliffs of Disappointment Island

My interest in White-chinned Petrels had to wait ten years until I could properly engage in all those brewing questions.  How many are there?  Where do they go to at sea?  Do different island populations forage in different areas, and how do they overlap with our fishing effort?  How are these different island populations related? It turns out that satisfactorily answering any one of these questions involved digging into the next, so I spent my PhD research at the University of Otago in Dunedin trying to pull together the lot.

In flight over a breeding colony on Disappointment Island.  Unlike smaller burrowing petrels, White-chinned Petrel do come ashore and land during daylight hours

The how many are there question was least known for two of the New Zealand populations (Auckland and Campbell Island groups).  Population size estimates involve getting a good count of all the burrows, and then finding out what is in them.  The challenges of vegetation, other wildlife and the White-chinned Petrel’s apparent preference for some steep and rugged country.

 
White-chinned Petrel breeding habitat on Adams Island; deep in lush vegetation, including the purple-flowering Campbell Island Carrot Anisotome latifolia, one of the island’s megaherbs

But questions about differences in island populations cannot be properly answered without data from all of them.  White-chinned Petrels breed on a number of island groups ringing the Southern Ocean: Marion, Prince Edward, Crozet, Kerguelen, Auckland, Campbell, Antipodes, Falklands/Islas Malvinas* and South Georgia/Islas Georgias del Sur*.  Researchers studying White-chinned Petrels at several of these localities have generously offered tracking data and blood samples from their work, and we did our best to fill the gaps by tracking and sampling at Auckland and Campbell Islands.

Out in the open on a rainy day on Disappointment Island, Auckland Islands

We are finding that New Zealand is home to a good quarter of the global White-chinned Petrel population; that they are returning to the main Campbell Island after being extirpated by rats (now eradicated); that petrels from different island populations do not share much of their foraging areas during the breeding season, but do overlap during their down-time in wintering areas; and that genetic differences show the species divides by oceanic basin into three evolutionarily significant units for management purposes.

White-chinned Petrel, Disappointment Island, Auckland Islands, January 2015

Those studies weren’t enough to get White-chinned Petrels out of my system.  I am now digging more into fisheries data to see what the tracked petrels can tell us about key areas and times when petrel fishing overlaps with human fishing, and what population(s) could benefit from targeted intervention there.  Our banding study in the Auckland Islands is simmering away.  There are limited opportunities to revisit the study colony, but every banded White-chinned Petrel in the hand adds to our ability to eventually look at adult survival.

Selected Scientific Publications:

Carneiro, A.P.B., Pearmain, E.J., Oppel, S., Clay, T.A., Phillips, R.A., Bonnet-Lebrun, A.-S., Wanless, R.M., Abraham, E., Richard, Y., Rice, J., Handley, J., Davies, T.E., Dilley, B.J., Ryan, P.G., Small, C., Arata, J., Arnould, J.P.Y., Bell, E., Bugoni, L., Campioni, L., Catry, P., Cleeland, J., Deppe, L., Elliott, G., Freeman, A., González-Solís, J., Granadeiro, J.P. Grémillet, D., Landers, T.J., Makhado, A., Nel, D., Nicholls, D.G., Rexer-Huber, K., Robertson, C.J.R., Sagar, P.M., Scofield, P., Stahl, J.-C., Stanworth, A., Stevens, K.L., Trathan, P.N., Thompson, D.R., Torres, L., Walker, K., Waugh, S.M., Weimerskirch, H. & Dias, M.P. 2020.  A framework for mapping the distribution of seabirds by integrating tracking, demography and phenology.  Journal of Applied Ecology doi.org/10.1111/13652664.13568 [click here].

Dilley, B.J., Hedding, D.W., Henry, D.A.W., Rexer-Huber, K., Parker, G.C., Schoombie, S., Osborne, A. & Ryan, P.G. 2019.  Clustered or dispersed: testing the effect of sampling strategy to census burrow-nesting petrels with varied distributions at sub-Antarctic Marion Island. Antarctic Science 31: 231-242.  [click here].

Elliott, G., Walker, K., Parker, G.C., Rexer-Huber, K. & Miskelly, C.M. 2020.  Subantarctic Adams Island and its birdlife.  Notornis 67: 153–187.

Miskelly, C.M., Elliott, G.P., Parker, G.C., Rexer-Huber, K., Russ, R.B, Taylor, R.H., Tennyson, A.J.D. & Walker, K.J. 2020.  Birds of the Auckland Islands, New Zealand subantarctic.  Notornis  67: 59–151. [click here].

Rexer‐Huber, K. 2017.  White-chinned petrel distribution, abundance and connectivity have circumpolar conservation implications.  PhD thesis, University of Otago, Dunedin, New Zealand.  166 pp.  [click here].

Rexer-Huber. K., Parker, G.C., Sagar, P.M. & Thompson, D.R. 2017.  White-chinned petrel population estimate, Disappointment Island (Auckland Islands).  Polar Biology 40: 1053-1061.  [click here].

Rexer-Huber, K., Thompson, D.R. & Parker, G.C. 2020.  White-chinned petrel (Procellaria aequinoctialis) burrow density, occupancy, and population size at the Auckland Islands.  Notornis 67: 387-401.  [click here].

Rexer‐Huber, K., Veale, A.J., Catry, P., Cherel, Y., Dutoit, L., Foster, Y., McEwan, J.C., Parker, G.C., Phillips, R.S., Ryan, P.G., Stanworth, A.J., van Stijn, T., Thompson, D.R., Waters, J. & Robertson, B.C. 2019.  Genomics detects population structure within and between ocean basins in a circumpolar seabird: the white‐chinned petrel.  Molecular Ecology doi:10.1111/mec.15248.  [click here].

Walker, K., Elliott, G.P., Rexer-Huber, K., Parker, G.C., McClelland, P. & Sagar, P.M. 2020. Shipwrecks and mollymawks: an account of Disappointment Island birds.  Notornis 67: 213-245.

Kalinka Rexer-Huber, Parker Conservation, Dunedin, New Zealand, 20 October 2021

*A dispute exists between the Governments of Argentina and the United Kingdom of Great Britain and Northern Ireland concerning sovereignty over the Falkland Islands (Islas Malvinas), South Georgia and the South Sandwich Islands (Islas Georgias del Sur y Islas Sandwich del Sur) and the surrounding maritime areas.

A Tristan Albatross chick in the Gonydale monitoring colony on Gough Island, now safe from mice?  Photograph by Michelle Risi

How have Critically Endangered Tristan Albatrosses Diomedea dabbenena been fairing on Gough Island since the completion of the bait drop against introduced House Mice Mus musculus by the Gough Island Restoration Programme (GIRP) earlier this year?  Seems there has been improvement in breeding success in some areas but not in others, as explained in a recent blog post:

“Every year our Overwintering Team conduct their ‘round island’ count at this time to establish how many Tristan albatross chicks survived the winter to reach a size and age at which they are likely to go on and fledge (in December). This year the weather was too poor for the team to complete the check in one (three-day long) trip and so we were made to wait on tenterhooks for a few days longer than usual. But the numbers are now in and it is fair to say it is a mixed bag.

We always expected chicks would still be lost this year, but we hoped to be able to start baiting before the worst of the winter hardships hit the mice – and consequently, the albatross. During incubation and for the first couple of months of its life, Tristan albatross chicks have a parent close by at all times. At the end of this brood-guard phase, the parents are (largely) both away at sea, returning to provision the chick but not to stay with it. It is possible that albatross chicks are particularly vulnerable at this point, and on Gough this vulnerability is likely exacerbated as it coincides with the start of winter when food options for mice begin to run out.

Our team do two round island counts – one at the start of the year and one in Sept/Oct. But between those times, they also make regular (approximately monthly) checks at two colonies that are closer to home – Tafelkop and Gonydale. At these two colonies, no fresh mouse wounds were observed after the first baiting in the area and chick survival was high. The figures from these sites are amazing – 70.9% at Gonydale and an astonishing 92.9% at Tafelkop – far higher than we’ve recorded before.

But all in all, breeding success for this year across the whole island comes in at 39.7% - not much higher than last year’s 37.2%.

It is crucial to appreciate that this is NOT indicative of the outcome of the eradication operation – most likely merely a reflection of the point at which we were able to distribute bait combined with the end of the brood-guard phase. Importantly, high breeding success across the island would not have been indicative of success either – if mice are still present on the island, they are likely to be few in number and may not need to attack albatross chicks to survive. This is part of the reason why we won’t be able to ascertain whether the eradication attempt was successful for at least two years. Hopefully we will, however, be able to report on greatly improved Tristan albatross breeding success before then.”

Note:  The ACAP Information Officer (with the essential help of friends and colleagues in the field) established the Gonydale and Tafelkop monitoring colonies by staking nests and colour- and metal-banding incubating adults of the two Tristan Albatross demi-populations over the consecutive summers of 2006/07 and 2007/08.  The news of vastly improved breeding success in these two study colonies is thus especially pleasing to him.

John Cooper, ACAP Information Officer, 20 October 2021