Danielle Keys with a Wandering Albatross chick in a long-term monitoring colony on Marion Island

The world-wide COVID-19 pandemic has deleteriously affected research and management activities at a number of oceanic islands that support breeding populations of ACAP-listed species, as previously featured in ACAP Latest News.  South Africa is no exception, with a governmental decision to halt all field work on its sub-Antarctic Marion Island from May this year due to virus concerns and not to replace the island’s researchers with a new team during the annual relief voyage in April/May.

Nico de Bruyn of the University of Pretoria’s Marion Island Marine Mammal Programme (MIMMP) studies three species of seals and Killer Whales or Orcas on the island.  A year break in data collection of individually marked animals would severely impact the value of the internationally respected and almost four decade-long studies of marine mammals that he leads.  A similar problem has ensued with demographic studies of individually colour-banded albatrosses and giant petrels undertaken without break since the 1980s by the University of Cape Town’s FitzPatrick Institute of African Ornithology; recently working in collaboration with the Marine Apex Predator Research Unit (MAPRU) of Nelson Mandela University and the and South African Department of Environment, Forestry and Fisheries (DEFF).

As described in an online article in the Earth Island Journal, Nico de Bruyn has been working towards getting some of the field researchers that were supposed to be part of Marion’s 77th overwintering team from May onto the island by other means.  The opportunity has now arisen with a film crew from Plimsoll Productions that wishes to visit Marion.  An agreement has been brokered with the authorities and a vessel is due to set off for the island in late September - with seven berths reserved for field researchers who will restart the seabird and seal monitoring projects which have been in abeyance for three months since the M76 team was taken off the island.

The seven-person field team will include two ornithological researchers (known at Marion as ‘birders’).  Danielle Keys, a MAPRU postgraduate student, will be looking at the link between demographics and foraging ecology of globally Vulnerable Wandering Albatrosses Diomedea exulans for her PhD.  Danielle has previously spent a year on Marion Island as a member of the M75 (2018/19) overwintering team when her research concentrated on deploying telemetry (GPS and GLS) devices on several albatross, petrel and penguin species, diet sampling, and collecting long-term demographic data on Wanderers.  This summer she will deploy more loggers and continue the monitoring of individually-marked birds that will also include Grey-headed Albatrosses Thalassarche chrysostoma and Northern Giant Petrels Macronectes halli.  Previously Danielle received an MSc with MAPRU for her research on the foraging ecology of Wedge-tailed Shearwaters Puffinus pacificus breeding on Seychelles and la Réunion.

Thando Cebekhulu at Kildalkey Bay, Marion Island with King Penguins Aptenodytes patagonicus, photograph by Bruce Dyer

The second birder is to be Thando Cebekhulu, who will work for DEFF.  Thando is also well experienced, having spent 2017/18 on the island with DEFF as a member of the 74th overwintering team.  His work will concentrate on undertaking censuses of surface-nesting breeding seabirds, including the island’s four species of penguins, for which census and other information following CCAMLR protocols has been collected for three species at Marion for 25 years without a break.  However, with only two ‘birders’ on the island much of their field work will need to be shared between them for practical and safety reasons.

Before sailing next month the vessel’s crew, film party and the seven new M77 team members will all need to be quarantined for 10 days prior to departure in a government-approved facility and tested to be shown to be COVID-19 free to avoid the risk of taking the virus to the island.

With thanks to Nico de Bruyn, Bruce Dyer, Danielle Keys, Azwianewi Makhado and Peter Ryan.

John Cooper, ACAP Information Officer, 18 August 2020

Grey-headed Albatross on Bird Island, South Atlantic, photograph by Richard Phillips

William Mills (British Antarctic Survey, Cambridge, UK) and colleagues have published in the journal Ibis on using stable isotopes to study non‐breeding adult Grey‐headed Albatrosses Thalassarche chrysostoma while at sea.

The paper’s abstract follows:

“The non‐breeding period is critical for restoration of body condition and self‐maintenance in albatrosses, yet detailed information on diet and distribution during this stage of the annual cycle is lacking for many species. Here, we use stable isotope values of body feathers (δ ¹³C, δ ¹⁵N) to infer habitat use and trophic level of non‐breeding adult Grey‐headed Albatrosses Thalassarche chrysostoma (n = 194) from South Georgia. Specifically, we: (i) investigate intrinsic drivers (sex, age, previous breeding outcome) of variation in habitat use and trophic level; (ii) quantify variation among feathers of the same birds; and (iii) examine potential carry‐over effects of habitat use and trophic level during the non‐breeding period on subsequent breeding outcome. In agreement with previous tracking studies, δ ¹³C values of individual feathers indicate that non‐breeding Grey‐headed Albatrosses from South Georgia foraged across a range of oceanic habitats, but mostly in subantarctic waters, between the Antarctic Polar Front and Subtropical Front. Sex differences were subtle but statistically significant, and overlap in the core isotopic niche areas was high (62%); however, males exhibited slightly lower δ ¹³C and higher δ ¹⁵N values than females, indicating that males forage at higher latitudes and at a higher trophic level. Neither age nor previous breeding outcome influenced stable isotope values, and we found no evidence of carry‐over effects of non‐breeding habitat use or trophic level on subsequent breeding outcome. Repeatability among feathers of the same individual was moderate in δ ¹³C and low in δ ¹⁵N. This cross‐sectional study demonstrates high variability in the foraging and migration strategies of this albatross population.”

Reference:

Mills, W.F., McGill, R.A.R., Cherel, Y., Votier, S.C. & Phillips, R.A. 2020.  Stable isotopes demonstrate intraspecific variation in habitat use and trophic level of non‐breeding albatrosses.  Ibis doi.org/10.1111/ibi.12874.

John Cooper, ACAP Information Officer, 17 August 2020

An elderly male Wandering Albatross Diomedea exulans and chick, near Prinsloomeer on Marion Island, photograph by John Cooper

Vonica Perold (FitzPatrick Institute of African Ornithology, University of Cape Town, South Africa) and colleagues have published in the Marine Pollution Bulletin on plastic ingested by albatrosses and giant petrels at sub-Antarctic Marion Island.  Fishery-related litter decreased with reduced local fishing effort, but non-fishery litter items increased between 1996 and 2018.

The paper’s abstract follows:

“Plastic ingestion by seabirds is an efficient way to monitor marine plastics. We report temporal variation in the characteristics of marine litter regurgitated by albatrosses and giant petrels on sub-Antarctic Marion Island between 1996 and 2018. Both fishery and other litter peaked during the height of the Patagonian toothfish fishery around the island (1997–1999). Comparing the two subsequent decades of reduced fishing effort (1999–2008 and 2009–2018), fishing litter decreased while other litter increased across all species. Litter increased most in grey-headed albatrosses, followed by giant petrels and wandering albatrosses. Similar ranked responses were found in the same species at South Georgia, but non-fishery-related litter has increased faster in the Indian Ocean than the southwest Atlantic, indicating regional changes in litter growth rates. These seabirds' regurgitations provide an easy, non-invasive way to track changes in oceanic litter in a remote area that is otherwise difficult to monitor.”

Reference:

Perold, V., Schoombie, S. & Ryan, P.G. 2020.  Decadal changes in plastic litter regurgitated by albatrosses and giant petrels at sub-Antarctic Marion Island.  Marine Pollution Bulletin 159.  doi.org/10.1016/j.marpolbul.2020.111471.

John Cooper, ACAP Information Officer, 14 August 2020

Short-tailed Shearwater at sea, photograph by Kirk Zufelt

Vincent Scoleri (School of Natural Sciences, University of Tasmania, Sandy Bay, Australia) and colleagues have published in the journal Biological Conservation on Tasmanian Devils Sarcophilus harrisii causing the extinction of a colony of Short-tailed Shearwaters Puffinus tenuirostris.

“Offshore islands are ideal for establishing insurance populations of endangered species as they often lack threatening processes found on mainlands. However, introductions of endangered predators can have complex effects on island species. The Tasmanian devil (Sarcophilus harrisii) was introduced to Maria Island in Tasmania, Australia in 2012 to establish an insurance population separate from a novel disease causing declines throughout its native range. Maria Island has small breeding colonies of the short-tailed shearwater (Puffinus tenuirostris) that are preyed on by an invasive mesopredator (feral cat, Felis catus) and an introduced native omnivore (common brushtail possum, Trichosurus vulpecula). We tested whether the introduction of devils increased predation pressure on shearwaters or reduced it by suppressing cat and possum activity. We measured predator activity on shearwater colonies, and surveyed burrow occupancy of shearwater adults and chicks, from 2013 to 2016; we also monitored shearwaters at a colony on a nearby island without terrestrial predators for comparison. Increasing devil activity was associated with decreasing total predator activity at shearwater colonies on Maria Island due to declines in possum and cat activity, evidently caused by predation on possums by devils, and competition with cats. However, shearwater colonies continued to decline, reaching zero occupancy within four years of devil introduction. Because of their larger size and ability to dig, devils had greater impacts on nesting shearwaters than either cats or possums. Conservation translocations of endangered predators must consider trade-offs between their protection and potential impacts on non-threatened native prey species.”

Reference:

Scoleri, V.P., Johnson, C.N., Vertigan, P. & Jones, M.E. 2020.  Conservation trade-offs: island introduction of a threatened predator suppresses invasive mesopredators but eliminates a seabird colony.  Biological Conservation 248.  doi.org/10.1016/j.biocon.2020.108635.

John Cooper, ACAP Information Officer, 13 August 2020