Agreement on the Conservation of Albatrosses and Petrels

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Read about recent developments and findings in procellariiform science and conservation relevant to the Agreement on the Conservation of Albatrosses and Petrels in ACAP Latest News.

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The effects of introduced mice on seabirds breeding at sub-Antarctic islands, a PhD thesis by Ben Dilley

 Ben Dilley Gough shrunk

Ben Dilley off the leeward coast of Gough Island, Churck Rock on the horizon

ACAP Latest News has regularly reported on the attacks on seabird by introduced House Mice on both Gough and Marion Islands and the research conducted to understand the problem and help direct planned eradication efforts (click here).  During separate year-long expeditions to both islands much of this research has been conducted by Ben Dilley, then a PhD student (now a Post-doctoral Fellow) of the University of Cape Town’s FitzPatrick Institute of African Ornithology.

Ben completed his thesis in 2018; with his Doctorate awarded in 2019 it is  now available online.  Most chapters are based on his published papers, that also have been featured on the ACAP website.  The thesis abstract follows:

“Seabirds play keystone roles as apex predators in marine ecosystems and also influence the ecology of terrestrial ecosystems where they breed. Seabirds are among the most threatened group of birds - almost half of all seabird species are known or suspected to be experiencing population declines with 97 (28%) of the 346 species currently classed as globally threatened and at risk of extinction. Introduced predators at oceanic islands where many seabirds breed account for the largest proportion of population declines, more so than incidental fisheries bycatch or degradation of their breeding habitats. Since few oceanic islands have escaped invasion, the problem is widespread, with the prime culprits being introduced cats Felis catus, rats Rattus spp. and house mice Mus musculus which depredate adult birds, chicks and eggs. Rats were widely introduced to thousands of islands and their catastrophic effects on seabird populations have been well documented. Mice are estimated to have invaded more oceanic islands than any other alien predator, but until fairly recently they were considered to have little impact on seabird populations. This thesis focuses on seabirds breeding at two large oceanic islands - Marion Island (293 km²) in the south Indian Ocean and Gough Island (65 km²) in the south central Atlantic Ocean. Both islands have mice as the sole introduced mammal. Of relevance to this study, however, is that the density of burrow-nesting petrels is much higher on Gough Island because Marion Island’s petrel populations were greatly reduced by cats, which were introduced in 1948 and eradicated by 1991. In the early 2000s, researchers on Gough Island identified mouse predation as the most probable cause of the high chick mortality of at least three species of seabirds, including the endemic Tristan albatross Diomedea dabbenena. Further research concluded that mice can be devastating predators of seabirds on islands where they are the sole introduced mammal, because in the absence of competition and predation from larger introduced species, mice can attain very high population densities, and resort to attacking seabird chicks mainly in winter when there are few other food sources. In 2003, the first mouse-injured wandering albatross Diomedea exulans chicks were found on Marion Island and in 2009 the first attacks on summer-breeding albatross chicks were recorded, but incidents appeared to be infrequent. Although mouse predation had been identified as a potentially serious threat to seabirds at both islands, further evidence was required on how many seabird species were being affected and to quantify the impacts. Field observations suggested a noticeable increase in levels of mouse predation at both islands, yet there was still no direct evidence of mice depredating burrow-nesting petrels at Marion. In this thesis I assess the impacts of invasive mice at both islands and establish pre-eradication baseline estimates for the burrow-nesting petrel populations at Marion Island. Burrow-nesting petrels are the most abundant seabirds in the Southern Ocean, yet their populations are poorly known compared to surface-breeding albatrosses because they are difficult to survey accurately. Extrapolation from density estimates can lead to large error margins, but these can be reduced with the development of repeatable, island-specific survey methods for long-term monitoring. This forms the basis of Chapter 2, where I test the effect of sampling strategy (random transect or systematic survey) on population size estimates of three burrow-nesting petrel populations at Marion Island. Systematic, island-wide surveys were appropriate to estimate the population sizes of blue petrels Halobaena caerulea (strongly clustered distribution - Appendix 1) and white-chinned petrels Procellaria aequinoctialis (moderately clustered distribution - Appendix 2) and but for the very widely distributed great-winged petrels Pterodroma macroptera I counted burrows within random transects and extrapolated burrow densities by associated habitat attributes to generate island-wide estimates. The systematic surveys required more effort, but resulted in more accurate estimates for species with clustered distributions, whereas the random transects required less effort but resulted in broad estimates with wide error margins which limits the ability to detect changes over time. In Chapter 3, I investigate how burrow-nesting petrel populations on Marion Island have recovered since cats were eradicated in 1991. In theory, the removal of cats as the super predator, combined with endogenous growth and the potential for immigration from nearby mouse-free Prince Edward Island, could have promoted a multi-fold increase in petrel numbers over the last two decades. To investigate this, I repeated a burrow-nesting petrel survey in the north-eastern sector of Marion Island originally conducted by Mike Schramm in 1979 and assessed how burrow densities have changed compared to densities at the peak of the cat-era. I found that burrow densities have increased by a modest 56% since 1979. The recovery of summer-breeding petrels decreased with decreasing body size, and winter breeding species showed even smaller recoveries, which is similar to patterns of breeding success at Gough Island where mice are the major drivers of population declines among petrels. Mice are the likely cause of the limited recovery of burrowing petrels at Marion Island. To assess and document the impacts of invasive mice at both islands, I installed infra-red video cameras into burrows and assessed breeding success with regular burrow-scope nest inspections of study colony nests at both Gough and Marion Islands (Chapters 4 and 5). The results show that mice can be very effective predators of burrow-nesting petrel chicks and to a lesser extent, eggs. The breeding success for winter breeders were lower than for summer breeders at both islands, and among winter breeders most chick fatalities were of small chicks less than 14 days old. Fatal mouse attacks on small chicks were video recorded for six burrow-nesting petrel species and winter breeders had very high chick mortality rates (e.g. 82–100% on Gough Island). Since mouse depredation of seabird chicks was first identified as a problem in 2001, the frequency and severity of mouse predations appears to have escalated on Gough (Appendix 3), yet on Marion Island detected incidents remained infrequent until 2015, when mice attacked 4.0–4.6% of the large chicks of all three albatross species that fledge in autumn. Attacks started independently in small pockets all around the island’s 70 km coastline, separated by distances hundreds of times greater than mouse home ranges. Attacks have continued from 2016–2018 at varying rates on summer-breeding albatross fledglings, showing how mice alone may significantly affect threatened seabird species (Chapter 6). In summary, mice appear to be suppressing the productivity of burrow- and surface-nesting seabird populations at both islands and are very likely causing population declines, especially among winter breeding species. Fortunately, the removal of invasive mice from islands through aerial spreading of toxic bait is a viable option and the scientific and visual evidence collected during this thesis has contributed to the growing body of evidence needed to persuade funders and Governments to support eradication operations at both study islands.”

Wounded chick Karen Bourgeois  Sylvain Dromzee shrunk

Following nocturnal attacks by mice on Gough Island, a Tristan Albatross chick has only hours to live, photograph by Karen Bourgeois and Silvain Dromzee

With thanks to Ben Dilley.


Dilley, B.J. 2018.  The effects of introduced mice on seabirds breeding at sub-Antarctic Islands.  PhD Thesis, Department of Biological Sciences, University of Cape Town.  195 pp.

John Cooper, ACAP Information Officer, 25 March 2020

The World Albatross Day Banner at Sea Challenge reaches South Africa

ATF South Africa 7 shrunk

Crew members on the Augusta 1 point to Albatross Task Force - South Africa's 'WAD2020' banner

BirdLife International’s Albatross Task Force (ATF) is an international team of bycatch experts dedicated to saving albatrosses and other seabirds by working on fishing vessels to promote the use of best-practice mitigation measures.  Since 2006 ATF teams have been working directly with both small-scale fishers and fishing companies to raise awareness and demonstrate the effectiveness of mitigation measures to fishing crews and thereby increase compliance with their use.  The ATF has field teams in five southern hemisphere fishing countries: Argentina, Brazil, Chile, Namibia and South Africa, with overall cordination coming from the UK’s Royal Society for the Protection of Birds (RSPB).

ACAP Latest News reached out to the five ATF teams with a request that they help raise awareness of this year’s inaugural World Albatross Day on 19 June by making banners to photograph out at sea on fishing vessels.  ATF-Chile was the first to respond, taking its banner to sea on a trawler back in December (click here).  South Africa has now followed suit and ATF-South Africa’s Instructor, Reason Nyengera took a most professional-looking ‘WAD2020’ banner out to sea into the rich fishing grounds of the Benguela Current last month. He was aboard the Augusta 1, a demersal long liner fishing for hake Merluccius, where he photographed the banner (see design below) with willing crew members.

Reason observes: “I’ve learnt that the fate of our seabirds lies in the hands of the fishers themselves.  Therefore, engaging with fishers during their daily operations is the greatest key to saving our precious albatrosses and petrels.”

ATF South Africa 5 Reason shrunk

ATF-South Africa’s Instructor, Reason Nyengera (left) and crew members on the Augusta 1 with Albatross Task Force - South Africa's 'WAD2020' banner

Andrea Angel is the Leader of the Albatross Task Force in South Africa.  Based with Reason in the Cape Town office of BirdLife South Africa, her role includes engaging with South African fishing fleets on the implementation and uptake of seabird bycatch mitigation measures and advancing policy and advocacy for seabird conservation in the Southern Ocean.  She writes to ACAP Latest News: “My passion for albatrosses stems from my life-changing experience of spending a year on Gough Island in 2003/04.  There I was awe struck by their beauty, their immense size and grace in the air.  As the stillness, that only remote places have, is broken by the whoosh of the wind through a Tristan Albatross’s flight feathers one can only be humbled.  I count myself as immensely privileged to have had the opportunity to come close to albatrosses and to dedicating the past 15 years of my career to safeguarding them.”

World Albatross Day SA ATF banner Jan 2020

ACAP Latest News has been sent photos of ‘WAD2020’ banners made by Albatross Task Force teams based in Argentina and Brazil that are being taken out to sea on fishing vessels.  Watch this space for more news of them!

John Cooper, ACAP Information Officer, 24 March 2020

Telomere length in Cory's Shearwaters is sex dependent in relation to age and reproduction

corys shearwater paulo catry

Cory's Shearwater, photograph by Paulo Catry

Christina Bauch (Marine and Environmental Sciences Centre, Lisbon, Portugal) and colleagues have published in the journal Molecular Ecology on telomere length and dynamics in Cory's Shearwaters Calonectris borealis breeding in a long-term study colony on Selvagem Grande, Madeiran Archipelago, Portugal.

The paper’s abstract follows:

“Individuals in free‐living animal populations generally differ substantially in reproductive success, lifespan and other fitness‐related traits and the molecular mechanisms underlying this variation are poorly understood.  Telomere length and dynamics are candidate traits explaining this variation, as long telomeres predict a higher survival probability and telomere loss has been shown to reflect experienced “life stress”.  However, telomere dynamics among very long‐lived species are unresolved.  Additionally, it is generally not well understood how telomeres relate with reproductive success or sex.  We measured telomere length and dynamics in erythrocytes to assess their relation to age, sex and reproduction in Cory's Shearwaters (Calonectris borealis), a long‐lived seabird, in the context of a long‐term study.  Adult males had on average 231 bp longer telomeres than females independent of age.  In females, telomere length changed relatively little with age, whereas male telomere length declined significantly.  Telomere shortening within males from one year to the next was three times higher than the inter‐annual shortening rate based on cross‐sectional data of males.  Past long‐term reproductive success was sex‐specifically reflected in age‐corrected telomere length: males with on average high fledgling production were characterised by shorter telomeres, whereas successful females had longer telomeres and we discuss hypotheses that may explain this contrast.  In conclusion, telomere length and dynamics in relation to age and reproduction are sex dependent in Cory's Shearwaters and these findings contribute to our understanding of what characterises individual variation in fitness.”


Bauch, C., Gatt, M.C., Granadeiro, J.P., Verhulst, S. & Catry, P. 2020.  Sex‐specific telomere length and dynamics in relation to age and reproductive success in Cory's Shearwaters.  Molecular Ecology

John Cooper, Information Officer, 21 March 2020

Gough Island mouse eradication project postponed due to COVID-19

 Tristan Albatross Michelle Risi Sam Greenhill

Gough Island's Critically Endangered Tristan Albatrosses are at serious risk to introduced House Mice

Artwork by Sam Greenhill‎, Artists & Biologists Unite for Nature, from a photograph by Michelle Risi

This austral winter the Gough Island Restoration Programme was set to attempt to eradicate House Mice on the island that kill large numbers of seabirds every year.  The project had started last month with the first field team being taken to the island on a yacht, with the second team due to depart from South Africa at the beginning of this week.  Now, because of restrictions placed on non-South Africans visiting the country (which would include essential team members transiting to Gough) due to the COVID-19 pandemic the Royal Society for the Protection of Birds (RSPB) has postponed the eradication until next year.

The statement by Martin Harper, RSPB’s Director of Global Conservation, follows in shortened form:

“One area of work where we have had to make an incredibly difficult but essential decision is with our Gough Island Restoration Programme.  Given the rapidly evolving COVID-19 pandemic and the increasing travel restrictions, it has clearly become impossible to complete the operation this season.

The decision to postpone was not easy but it is the right one.  The amazing team behind the work are understandably hugely disappointed after the massive effort and hard work that has got us to this point.  However, given the circumstances it has become logistically impossible, and contrary to government guidance, for our specialist team to travel to South Africa and onto Gough during the pandemic.  We know that after all the years of planning that the project could save two million seabirds each year and prevent the extinction of a number of species.  But we only have one shot, and to get it right in such a remote place and at such a scale, all the stars must be aligned.  And for this year they are not.

We are committed in our mission to restore Gough to the seabird paradise it once was.  A great many people and organisations have joined and helped us on this project and we owe it to them as well as to our ourselves to make sure that we give ourselves the best chance of success.  We also owe it to our funders and all the people who have generously donated to the project to do the same.

The team on the island have already made great inroads on the initial project set up. This progress will stand us in good stead for next year. We now need to concentrate on getting our people back home safely and planning for the return visit."

With thanks to Pete McClelland, Operations Manager, Gough Island Restoration Programme

John Cooper, ACAP Information Officer, 20 March 2020

The conservation team on Midway Atoll helps advertise World Albatross Day

Sand Island Amanda Boyd cropped shrunk 

From left: Jimmy Breeden, Kelly Goodale, Elaine Beaudoin, Joanna Morelli, Nicole Faber, Joey Latsha, Emily Jankowski, William Kennerley, Jon Plissner, Tim Clark, Virginie Ternisien, Tristen Luxner, Suzanne Pluskat, Alex Chmielewski, Amanda Boyd and Stephen Barclay, 29 February 2020; photograph by Amanda Boyd

Back in January ACAP Latest News featured a group of volunteers visiting Midway Atoll’s uninhabited Eastern Island in the North Pacific for the annual albatross count.  While on the island they signalled their support for the inauguration of World Albatross Day on 19 June this year by gathering for a photo behind their hand-drawn sign made by volunteer Caren Loebel-Fried.

During her time on Midway, Caren requested that a similar photo be taken on the larger inhabited Sand Island with the atoll’s combined conservation team.  In response no less than 16 U.S. Fish and Wildlife Service (USFWS) volunteers, interns and staff, Pacific Rim Conservation staff and Island Conservation staff gathered last month in front of the refuge sign on Sand Island holding up four sheets of paper printed with  the words WORLD ALBATROSS DAY 19 JUNE 2020.  A look at the photo shows that a seemingly bashful Laysan Albatross centre stage has turned its back on the camera, no doubt waiting patiently for peace and quiet to return.  Many more Laysans can be seen gathered for the breeding season in the background.

ACAP Latest News is appreciative of the conservationists on Midway finding time to gather in support of ‘WAD2020’, especially as there is a lot going on at the atoll this year to keep them all busy.  Most important will be the effort set to take place in a few months’ time to eradicate the introduced House Mice that have taken to attacking breeding albatrosses on Sand Island (fortunately Eastern Island remains mouse free).

And of course, among the hundreds and thousands of albatrosses that breed on the atoll to look after there are two world-famous pairs of albatrosses to keep a watchful eye over: 69-year old Laysan Albatross Wisdom and her mate Akeamakai (currently on a ‘gap year’) and George and Geraldine, the only Short-tailed Albatross pair that breeds successfully outside Japan - whose current chick, their second, is growing apace.

Wisdom and mate Nov2015 Kiah Walker s


Georg Geraldine 2018Madalyn Riley








 Wisdom & Akeamakai, 2015, photo by Kiah Walker

George & Geraldine, 2018, photo by Madelein Riley

Recognition of World Albatross Day has also come from the Friends of Midway Atoll National Wildlife Refuge which supports conservation work on the atoll (click here).

With thanks to Stephen Barclay, Acting Manager, Midway Atoll National Wildlife Refuge and Caren Loebel-Fried.

John Cooper, ACAP Information Officer, 19 March 2020

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