Areas of Ecological Significance identified include around sub-Antarctic islands where most ACAP-listed species breed

Mark Hindell (Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia) and many colleagues have published in the journal Nature on tracking marine predators to protect Southern Ocean ecosystems.

The paper’s abstract follows:

“Southern Ocean ecosystems are under pressure from resource exploitation and climate change.  Mitigation requires the identification and protection of Areas of Ecological Significance (AESs), which have so far not been determined at the ocean-basin scale.  Here, using assemblage-level tracking of marine predators, we identify AESs for this globally important region and assess current threats and protection levels.  Integration of more than 4,000 tracks from 17 bird and mammal species reveals AESs around sub-Antarctic islands in the Atlantic and Indian Oceans and over the Antarctic continental shelf.  Fishing pressure is disproportionately concentrated inside AESs, and climate change over the next century is predicted to impose pressure on these areas, particularly around the Antarctic continent.  At present, 7.1% of the ocean south of 40°S is under formal protection, including 29% of the total AESs.  The establishment and regular revision of networks of protection that encompass AESs are needed to provide long-term mitigation of growing pressures on Southern Ocean ecosystems.”

Read popular accounts of the publication here and here.

Reference:

Hindell, M.A., Reisinger, R.R., Ropert-Coudert, Y. et al. 2020.  Tracking of marine predators to protect Southern Ocean ecosystems. Nature  doi.org/10.1038/s41586-020-2126-y.

John Cooper, ACAP Information Officer, 28 March 2020

Results of mouse attacks on Laysan Albatrosses on Midway Atoll

The postponement of this year’s attempt to eradicate House Mice on Gough Island due to travel restrictions in relation to the COVID-19 pandemic was recently reported in ACAP Latest News (click here).  Now comes the news that a similar operation also set to take place on Midway Atoll this year has been postponed – for much the same reason, but  additionally due to concerns over ‘social distancing’.

The statement from the Pacific Region of the US Fish and Wildlife Service follows in full:

“Due to the rapidly evolving outbreak of respiratory disease caused by a novel (new) coronavirus (COVID-19), increasing travel restrictions, and following new guidance from the White House and Centers for Disease Control and Prevention (CDC) for reduced travel and social distancing, it has become necessary to postpone the implementation of the Seabird Protection Project.  Right now we are working hard to ensure that the planning and preparation of the past three years is not lost, and we are coming up with a path forward to ensure that we are in the best possible place to complete this project in the future.

Although this was a difficult call to make, the safety and health of our staff and volunteers [have] to be paramount.  We are closely monitoring the situation, keeping staff informed, and taking action as needed by following the most current guidance from the CDC, OPM, OEM and other health authorities.

In addition to the health concerns, the increasingly uncertain nature of travel restrictions occurring during some of the key early implementation stages of the project made it clear that moving forward now was simply not feasible.

Midway Atoll is one of the most important seabird colonies in the world, and we remain committed to ensuring that the birds who rely on Midway have a safe and rodent-free future. When we move forward with this project we have to do it the right way, and with the best possible chance at success.

We are incredibly grateful for the work that has been done already and remain more committed than ever to protecting Midway’s seabirds. Follow us here for continued updates as we move forward.”

The Gough and Midway eradication projects planned to take place this year – but now both postponed at least until 2021 – were together a large reason why this year’s inaugural World Albatross Day adopted the theme ‘Eradicating Island Pests’.  Some irony here, but ACAP Latest News expects the two eradication efforts will eventually take place - and will continue to report on them as new information comes to hand.

John Cooper, ACAP Information Officer, 27 March 2020

Attendees at the Fitztitute 2020 AGM with a World Albatross Day banner, held by ACAP's Information Officer and Andrea Angel

The FitzPatrick Institute of African Ornithology (known as the ‘Fitztitute’), located within the Department of Biological Sciences at the University of Cape Town, South Africa, is widely regarded as one of the world’s premier bodies for avian research.  Established in 1959, the Institute was identified as a Centre of Excellence (CoE) by the South African Department of Science and Technology and the National Research Foundation in 2004.  It houses the Niven Library, surely Africa's most comprehensive ornithology collection of books, journals and papers.

Peter Ryan, the Fitztitute’s current (and fifth) Director, is the only A-rated ornithologist in the country.  His wide-ranging research interests have centred on seabirds and islands.  ACAP Latest News approached Peter with the request the Institute lends its support for this year’s inaugural World Albatross Day – which was readily granted.  Earlier this month, the Fitztitute held its Annual General Meeting, when postgraduate students give talks to the Institute’s Board and interested university staff and students.  A group photo is a traditional part of the AGM.  Fitztitute graduate Andrea Angel, who is Leader of BirdLife International’s Albatross Task Force in South Africa, brought along a World Albatross Day banner to photograph with the AGM attendees and with albatross researchers currently based at the Fitztitute.

In addition to the photo opportunity, statements of support for ‘WAD2020’ have come from past and present Fitztitute personnel who have worked with albatrosses as set out below:

“It's always a stirring sight to see an albatross, whether soaring over the open ocean, or displaying at their breeding islands.  I hope that World Albatross Day will bring them to the attention of the many people who are unable to see them in the wild”. - Peter Ryan, Director, FitzPatrick Institute.

“Albatrosses are the most threatened group of seabirds.  The biggest threats to their survival are incidental bycatch in fisheries, climate change and invasive alien species at their breeding colonies.  World Albatross Day is a fantastic way to shine a spotlight on these majestic birds and to make people aware of how we can conserve them.” - Kim Stevens, Ph.D.student, FitzPatrick Institute (The foraging ecology and breeding success of Grey-headed Albatross Thalassarche chrysostoma).

“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.” - Andrea Angel, Albatross Task Force, BirdLife South Africa.

“I found it fascinating getting to know individual albatrosses while doing colony checks of incubators at their breeding colonies – it may sound a bit odd, but just like pets in our homes, albatrosses have their quirks – some would nibble your glove, some would unfold their leg to helpfully reveal their band, while others were  always snappy!  They’re so elegant and really are remarkable birds”. - Ben Dilley, Postdoctoral Fellow, FitzPatrick Institute.

From left: Ben Dilley, ACAP's Information Officer, Peter Ryan, Andrea Angel and Kim Stevens with the Albatross Task Force's WAD2020 banner

With thanks to Andrea Angel, Albatross Task Force and Ben Dilley, Peter Ryan & Kim Stevens, FitzPatrick Institute of African Ornithology.

John Cooper, ACAP Information Officer (and Fitztitute staff member 1973-1994), 26 March 2020

Note:  this meeting and photo opportunity took place shortly before COVID-19 reached the Western Cape, and thus before social distancing became part of the 'new normal'.

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.”

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.

Reference:

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