A White-chinned Petrel; photograph by Richard Phillips from the Bristish Antarctic Survey (BAS)

Lily K. Bentley (Department of Zoology, University of Cambridge, UK) and colleagues have published open access in the journal IBIS on the differing foraging habitat preferences between the Grey Petrel Procellaria cinerea and White-chinned Petrel P. aequinoctialis from colonies on Gough Island and Bird Island (South Georgia*).

The paper’s abstract follows:

“Foraging niche specialisation is thought to occur when different members of speciose communities divide resources in either time or space. Here we compared habitat preferences of the congeneric Grey Petrel Procellaria cinerea and White-chinned Petrel P. aequinoctialis, tracked in the same calendar year using GPS loggers from Gough Island and Bird Island (South Georgia), respectively. We identified periods of active foraging and determined habitat characteristics using remote-sensing data. Although these highly pelagic species could potentially overlap at sea across large areas, they showed markedly different foraging preferences during their incubation periods, which are temporally offset because Grey Petrels breed during the austral winter. Grey Petrels foraged mostly in pelagic cold-water areas to the north-west of South Georgia, whereas White-chinned Petrels foraged almost exclusively in the warm, shallow waters of the Patagonian Shelf. Within each species, foraging habitat characteristics were highly consistent. Our results demonstrate the diversity of habitat preferences within genera, and provide further evidence that colony-specific information on habitat preference is crucial to identify important feeding areas for pelagic predators.”

Reference:

Bentley, L.K., Manica, A., Dilley, B.J., Ryan, P.G. and Phillips, R.A. (2022), Divergent foraging habitat preferences between summer-breeding and winter-breeding Procellaria petrels. Ibis. Accepted Author Manuscript. https://doi.org/10.1111/ibi.13152

*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 colour-banded Northern Royal Albatross rises over its egg at Taiaroa Head in November 2016

Four recently laid eggs of the globally Endangered and nationally Vulnerable Northern Royal Albatross Diomedea sanfordi are suspected to have been stolen from the mainland colony at Taiaroa Head/Pukekura on the Otago Peninsula, South Island, New Zealand (click here).  The eggs were noticed missing on 10 November during routine checks by Department of Conservation (DOC) rangers, who have been left feeling “devastated”.  It is thought the eggs may have been taken as there are no signs they were eaten by predators.  DOC compliance officers and police are investigating.

The colony is a fenced nature reserve, with entry by permit only.  Northern Royal Albatrosses are protected under the Wildlife Act 1953 and it is an offence to kill, injure, harass or disturb them (including their eggs).  It is reported that the affected parents have all been given dummy eggs to incubate in case they will be needed as foster parents.  This is a normal management technique in the colony for birds that lose their own eggs.

In a New Zealand Herald article on the incident, Lyndon Perriman, who worked as a ranger at Taiaroa Head between 1989 and 2016, said there had been no such occurrences during this time there.  He thought it unlikely that a pest predator was responsible: “Stoats, ferrets or cats... they certainly couldn’t take away an albatross egg without breaking it.”   The supposed theft has now prompted a review of security at the site, Lyndon noting there was a gap in the fence.

It seems the only previous incident of stealing eggs at Taiaroa Head was in the very early days in the 1930s when eggs were taken each year prior to Lance Richdale protecting the solitary breeding pair until its chick fledged (click here).  For albatrosses (which usually breed on non-inhabited islands) a somewhat similar case occurred with 15 breeding Laysan Albatrosses Phoebastria immutabilis being killed and their eggs smashed by juvenile vandals within the fenced colony in the Kaena Point Natural Area Reserve on the Hawaiian island of Oahu.  This incident led to a successful prosecution (click here).  ACAP Latest News will report if the Taiaroa Head egg loss results in anything similar.

The orphan Northern Royal Albatross close to fledging, photograph by Laura Findlay

Related news is that the 2021/22 breeding season resulted in 25 Northern Royal Albatross chicks fledging from Taiaroa Head, out of 36 eggs laid, giving an overall breeding success of 69.4%.  The first to fledge was the live-streaming Royal Cam’s Lilibet, named after the childhood nickname of the late Queen Elizabeth II; the last to fledge left on 10 September.  An orphaned chick fledged over 2/3 October.  Since its foster parents went missing in April, it had been hand fed over 111 kg of fish, squid and octopus.

The 2022/23 season’s Royal Cam pair will be chosen near the end of November once all of the new season’s eggs have been laid.  Prior to the egg napping, it was hoped over 40 eggs would be laid.  As of 9 November, 23 eggs have been counted, with 135 returning colour-banded adults recorded.

The Northern Royal Albatross is one of two albatross species chosen to be featured for next year’s World Albatross Day on 19 June with its theme of “Plastic Pollution”.  Posters and an infographic sponsored by the New Zealand Department of Conservation featuring the bird will be produced next year for “WAD2023” in ACAP’s three official languages of English, French and Spanish.

John Cooper, ACAP News Correspondent, 17 November 2022

The SCAR Plastic in Polar Environments Action Group (Plastic-AG) is requesting data from national and international projects focused on plastic pollution in the Antarctic and sub-Antarctic regions for an open access repository. The repository file will be made available on the SCAR Plastic-AG website.

The initiatives’ aims, as stated on the website, are to: “examine the presence, origin and biological effects of macro-, micro- and nanoplastics; quantify the scale of the problem; and propose solutions for minimising the environmental risk and impacts on Polar ecosystems”.

Contributors are asked to fill in a short form including details of their ongoing and past project(s) on Antarctic/sub-Antarctic plastics and submit it to SCAR Plastic-AG. 

Further information on the initiative and how to submit your data can be found at the SCAR Plastics-AG website. The deadline for submissions is 30 November.

Plastic Pollution is a burgeoning environmental issue and is the theme ACAP has chosen to highlight for the fourth World Albatross Day to be marked on 19 June 2023. The globally Endangered Northern Royal Albatross D. sanfordi, endemic to New Zealand, and the abundant and widespread Black-browed Albatross Thalassarche melanophris are two albatross species being featured to highlight 2023's theme and range in sub-Antarctic and Antarctic (though rarely for the Northern Royal) waters.

16 November 2022

 
Free from mice attacks: a healthy 2021/22 Tristan Albatross chick on Gough Island; photograph by Roel Daling, Gough Island Restoration Project

In the austral winter of 2021, the Gough Island Restoration Project (GIRP) attempted to rid Gough Island in the South Atlantic of its albatross-killing House Mice Mus musculus by an aerial drop of cereal pellets laced with a rodenticide.  However, in December that year the first signs of mice being still present on the island were reported.  Subsequent surveys have shown that mice remain widespread (but presumably still in low numbers) over the island (click here).  Despite this, the island’s seabirds have been breeding much more successfully this year.  According to GIRP’s Facebook page “in June the island reported no signs of mouse attacks on 2022’s [Critically Endangered] Tristan Albatross [Diomedea dabbenena] chicks, although in previous years wounded chicks have been seen from the start of April.”

A later GIRP Facebook report gives more detail: “Despite horrible weather on Gough our amazing team counted 1186 Tristan Albatross chicks from 1570 breeding pairs, which results in a breeding success of 75.5%.  This is more than twice as high as the average from 2004-2021.  The greatest increase came from areas in the north-western part of the island, which have historically had very poor breeding success.  The team counted 201 chicks at West Point (previous years 30-50) and 177 in Giant Petrel Valley (previous years 30-90).  This shows what their future could look like on a mouse-free Gough and hardens our resolve to return.”  Based on monthly surveys in study colonies, few of the chicks counted last month are expected to die before fledging, so is to be expected that most of the 1186 counted will successfully leave the island around year end.

“Breeding success of Tristan Albatrosses on Gough Island from 2004 to 2022.  The horizontal dashed line is the typical breeding success on predator-free islands that would be sufficient for an albatross population to maintain itself.  In 2022 [red dot] the Tristan Albatrosses on Gough exceeded this threshold for the first time since records began”, graph by the Gough Island Restoration Project

The ACAP-listed and Near Threatened Grey Petrel Procellaria cinerea also had a good year on Gough with a 75% breeding success, compared to a typical rate of 30% prior to the mouse eradication attempt.  Because this burrowing petrel is a winter breeder, its chicks were at particular risk to mice, made hungry by seasonally diminishing food sources, such as grass seeds and invertebrates.  Likewise, two other largely winter breeders did well: “the Critically Endangered MacGillivray’s Prion [Pachyptila macgillivrayi] increased breeding success from an average of 6% with mice (including many years of 0% success) to 82% in 2022, whilst the Endangered Atlantic Petrel [Pterodroma incerta] had a 63% breeding success – more than double the previous year’s rate and well above average.  Gough Island is the global stronghold for both species”.

Not to be outdone, summer-breeding Endangered Atlantic Yellow-nosed Albatrosses Thalassarche chlororhynchos, known to be attacked by mice, achieved a 77% breeding success, and the equally Endangered Sooty Albatrosses Phoebetria fusca achieved 74%, figures comparable to those from mouse-free islands, and a marked increase to those of previous years.

The GIRP ends its blog on a cautionary note: “Mice are omnivores and will primarily eat seeds, plants, and invertebrates.  When mice become very abundant there is intense competition for food, and plant and invertebrate food sources can become depleted. Out of desperation hungry mice will then explore alternative food sources – and on Gough Island they started eating seabirds.  In 2022 the low numbers of mice (and hence low competition) meant they had plenty of other food to eat, and the seabirds were able to raise many chicks.  Unfortunately, we do not believe that this situation will persist.  We expect mice will become so abundant that they deplete their typical food sources and then start eating seabirds once again.   We do not know when this will happen, but as long as mice remain on Gough Island the future for seabirds is not secure. This year has shown us what seabirds can achieve when their chicks are not eaten by mice – and this gives us a determination to return to Gough in the future and remove the mice forever.”

Read more here and in the latest edition (No. 12) of GIRP’s newsletter Island Restoration News.

A PERSONAL NOTE:  With the essential help of many colleagues, I set up the long-term monitoring colonies of the three breeding albatross species and the Southern Giant Petrel Macronectes giganteus on Gough, staking nests and metal- and colour-banding incubating adults over my 18 enjoyable visits to the island (which included over-summering twice) from 1981 to 2013.  It is thus a great pleasure indeed to read of the high breeding successes achieved in the 2021/22 breeding season.  I can only hope they will continue for a few more years until a second eradication attempt finally rids Gough of its introduced House Mice.

John Cooper, ACAP News Correspondent, 15 November 2022