The Million Dollar Mouse project works towards its ultimate success as a bait bucket is loaded at last light on Antipodes Island; photograph by Keith Springer

Note:  In this guest article, Keith Springer, Operations Manager for South Africa’s Mouse-Free Marion Project, writes about a suite of publications in a special issue of the New Zealand Journal of Ecology on the restoration of New Zealand’s sub-Antarctic islands.  A Table of Contents with linked titles and lead authors follows his article.

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For many years now, New Zealand has put significant effort and resources into managing pest animal species on its sub-Antarctic islands.  There are five main groups, Antipodes Island, Auckland Islands, Bounty Islands, Campbell Island and The Snares, that together form the New Zealand Sub-Antarctic Islands World Heritage Site.  The Bounty Islands and The Snares have never had introduced mammals establish on them — they have remained animal pest-free.

A rare breed in the cross hairs?  A feral pig forages among washed-up kelp along the shore on Auckland Island; photograph by Pete McClelland

The other three island groups all had numerous species of introduced mammal established.  This occurred for several reasons.  Some animals established either from shipwrecks or from stowaways in the stores and equipment brought by the first European visitors – the sealers and whalers of the early 19th Century.  This typically included rats, mice, cats, and sometimes, dogs.  Because the islands lay on the ‘Great Circle’ shipping route – in the days of sail, ships bound from Australia to England sailed these latitudes to pick up the prevailing westerly winds – shipwrecks were common (the location of Auckland Islands being incorrectly marked on the charts didn’t help).  As a result, animals like goats, pigs and rabbits were introduced so that shipwrecked sailors might find sustenance.  Finally, the government let grazing leases on some islands, so cattle and sheep were taken there as part of farming operations.

Over the years, the sealing and whaling industries collapsed, steam ships replaced sail, so the Great Circle Route fell into disuse and the grazing leases were cancelled.  However, the animals remained, and diminished the biodiversity values of the islands by eating seabirds, land birds, invertebrates and by grazing the vegetation.  The sum of these impacts was a significant deterioration of the ecological condition of those islands with introduced pests.

 
A globally Endangered Antipodean Albatross Diomedea antipodensis feeds its chick on Antipodes Island; photograph by Keith Springer

From the 1980s, the then-New Zealand Wildlife Service set about trying to address these impacts, although a paper in the Proceedings of the New Zealand Ecological Society of 1968 had discussed this strategy earlier.  The ungulates were the easiest to remove, with sheep, cattle and goats eradicated by shooting campaigns.  With the establishment of the Department of Conservation in 1987 this work continued, with European Rabbits and House Mice removed from two smaller islands in the Auckland group.  Small by our standards now, that is, but ground-breaking efforts at that time.  This momentum saw Campbell Island cleared of Norway Rats in 2001, which has been the inspiration for many pest eradications on islands in the Southern Ocean ever since, notably on Macquarie and South Georgia (Islas Georgias del Sur)*.  House Mice were removed from Antipodes Island in 2016, and planning has been underway for some time to consider removal of mice, pigs and cats from 45 891-ha Auckland Island.  If accomplished, this would remove the last invasive mammal species from all the island groups in the World Heritage Site.

An immense body of knowledge and experience has been built up in the roughly 35 years of eradication activity on these islands, and each has informed and refined methodology for the next – not only in the New Zealand region, but on islands throughout the Southern Ocean.

 A luxuriant carpet of the megaherb Great Emperor Daisy Pleurophyllum speciosum on Campbell Island – these verdant flower-fields have recovered now that they are free from grazing by the eradicated sheep; photograph by Keith Springer

Now, a special edition of the New Zealand Journal of Ecology collates information in 19 open-access papers on topics relating to many of these eradications on the New Zealand sub-Antarctic islands (the Campbell rat and Antipodes mouse eradications have been published elsewhere).  The edition also reports on other island eradications in New Zealand that were partly conducted as trial projects to inform the planned mouse eradication on Auckland Island, or that informed other aspects of the multi-species eradication planned for Auckland Island, such as potential methods for cat eradication on Stewart Island.  There is also a paper describing the introduced mammals that were brought back to New Zealand so that populations of these genetically isolated breeds could be maintained.  After all, most of the ungulates and lagomorphs on these islands had descended from genetic bloodlines that existed up to 200 years ago and have been isolated from others of their species ever since.

Of particular interest is the number of papers regarding the eradication of mice, including several where different bait application rates were trialled.  As noted, mouse eradication was achieved on Antipodes Island and may be attempted on Auckland Island, following some years of research and planning.  The planned eradication on Marion Island by the Mouse-Free Marion Project is certainly ambitious but undertaking this on Auckland Island – 50% larger than Marion – would be an even greater challenge, especially given the complexities caused by the presence of cats, pigs and large areas of scrub and forest.

A special-topic journal issue such as this one really does crystalise just how much has been achieved in the eradication of mammalian pests from sub-Antarctic islands.  Of even greater importance, it also describes the ends to which eradication is the means; that is - the ecological recovery that results from these management interventions.

Keith Springer, Operations Manager, Mouse-Free Marion Project, 22 December 2022

New Zealand Journal of Ecology, Volume 46(3), 2022

Table of Contents

Editorial: Restoration of New Zealand subantarctic islands by James Russell et al.

The eradication of Campbell Island sheep and subsequent ecological response by Derek Brown et al.

The hunting-assisted demise of Campbell Island cattle by Derek Brown et al.

The eradication of cattle from Enderby Island and subsequent ecological response by Derek Brown et al.

The eradication of feral goats from Auckland Island by Derek Brown et al.

Introduction, rescue, and subsequent history of Auckland Islands livestock by Michael Trotter et al.

Eradication confirmation of mice from Antipodes Island and subsequent terrestrial bird recovery by Stephen Horn et al.

Analysis of spatiotemporal patterns of home range use and habitat selection to inform management of feral pigs on Auckland Island by Dean Anderson et al.

A local eradication pilot study of methods for feral pig eradication on Auckland Island by Finlay Cox et al.

Use of automatic feeders to attract feral pigs on Auckland Island by Finlay Cox & Norm Macdonald

A field test of the anaesthetics, surgical methods and radio-transmitters required for producing Judas pigs for an eradication programme by Kate McInnes et al.

Spatial ecology meets eradication of feral cats on Auckland Island by Mariano Rodriguez-Recio et al.

Monitoring and detection of feral cats on Auckland Island by Alistair Glen et al.

Field palatability and degradation of a selection of feral cat bait matrices on Auckland Island by Finlay Cox et al.

Feral cats on Rakiura Stewart Island: population attributes and potential eradication tools by Alistair Glen et al.

Population trends of house mice during tussock mast seeding on Auckland Island by Rachael Sagar et al.

How low can you sow?  House mouse eradication on Motuareronui/Adele Island by James Livingstone et al.

A trial on Te Pākeka/Maud Island for reducing aerial baiting sow-rates for the eradication of house mice by Emmanuel Oyston et al

The next frontier: assessing the feasibility of eradicating mammalian pests from Auckland Island by Stephen Horn et al.

*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.

Hobart, Tasmania. The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) has its headquarters in the Tasmanian capital city.

Current and past members of ACAP represented the Agreement across several meetings at the recent Forty-first Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) and its Scientific Committee, held in Hobart, Tasmania last month.

ACAP welcomes the decision taken by last year’s CCAMLR Commission, following recommendations from the Scientific Committee,  to re-establish the Working Group on Incidental Mortality Associated with Fishing (WG-IMAF).  ACAP has been extended an ongoing invitation for an ACAP expert to participate in the WG-IMAF. ACAP’s Seabird Bycatch Working Group Convenor Dr Igor Debski attended the 2022 meeting in this capacity.

The WG-IMAF was originally created in response to concerns over the decline in albatross populations, and the potential for this to be exacerbated by interactions with CCAMLR fisheries. The group met predominantly on an ad hoc basis from 1994 up until 2011; however, following a decision at SC-CAMLR-40, WG-IMAF reconvened in 2022 to review mitigation of incidental mortality in the krill trawl fishery. The current Co-conveners of WG-IMAF are Mr Nathan Walker (New Zealand) and Dr Marco Favero (Argentina), both former ACAP Advisory Committee Chairs, with Dr Favero also being the ACAP Executive Secretary from 2016 to 2018.

ACAP’s Executive Secretary, Dr Christine Bogle, and Science Officer, Dr Wieslawa Misiak, attended the CCAMLR Scientific Committee, where they were joined by Dr Igor Debski. The Executive Secretary and the Science Officer also represented ACAP at the Commission meeting. 

A list of the meetings and reports (including the CCAMLR-41 preliminary report) is available here.

21 December 2022

The Northern Giant Petrel spotted off the coast of Washington in 2019 and reported on by ACAP in January 2020, photograph by Zed Blue

The Northern Giant Petrel Macronectes halli is one of 16 birds the U.S. Fish and Wildlife Service (USFWS) is proposing to add to the list of birds protected by the Migratory Bird Treaty Act (MBTA).

The list reflects changes in taxonomy and accepted use, as well as new evidence regarding the natural occurrence or absence of species in the United States or U.S. territories. The inclusion of the Northern Giant Petrel is based on new distributional records documenting its occurrence in the United States or U.S. territories. 

In January of 2020, ACAP Latest News reported on the sighting of a Northern Giant Petrel from a fishing vessel off the coast of Washington, USA in the North Pacific on 8 December 2019. 

The proposal would add 16 species and remove three, bringing the total number of species protected by the MBTA to 1,106. Names changes would affect 30 other listings. 

Although the USA regularly attends and contributes to ACAP meetings, and despite repeated bipartisan efforts over the years to introduce enabling legislation to its House of Representatives, it is not yet a Party to the Agreement. ACAP and the National Audubon Society have previously reported on the efforts by the USA to become a Party to ACAP. 

The proposed Revised List of Migratory Birds made by the USFWS is available here, and comments can be submitted on the proposal through February 10, 2023.

21 December 2022

Common Diving Petrel in the hand on Marion Island, photograph by Stefan Schoombie

Maëlle Connan (Marine Apex Predator Research Unit, Institute for Coastal and Marine Research, Nelson Mandela University, Gqeberha, South Africa) and colleagues have published in Ostrich Journal of African Ornithology on the recent recolonisation of Marion Island by Common Diving Petrels Pelecanoides urinatrix, over two decades after the eradication of feral cats Felis catus in 1991.  The cats were introduced in 1948 and are thought to have caused the diving petrels’ extirpation soon afterwards.

Lead author Maëlle Connan writes to ACAP Latest News:  “further work is needed to understand the reasons for the low hatching success observed and whether predation by House Mice Mus musculus mice may be a contributing factor”.

At risk to mice?  Burrowscope photographs of a Common Diving Petrel adult alongside its egg (left) and a chick (right); by Stefan Schoombie

The paper’s abstract follows in English and French:

Nocturnal burrow-nesting seabirds are notoriously difficult to study and can go unnoticed for years in remote  areas. One of these species is the Common Diving Petrel Pelecanoides urinatrix, which has a circumpolar breeding distribution in the Southern Ocean, including at the sub-Antarctic Prince Edward Islands.  At Marion Island, the larger of the two islands, the species was extirpated by cats that were introduced in 1948.  The cats were eradicated by 1991, and Common Diving Petrels were discovered in burrows in coastal Poa cookii (Cook’s tussock grass) on a steep south-facing slope in Goodhope Bay during April 2015.  Subsequent surveys in October 2015 and February 2016 confirmed breeding over a 1-ha area.  In 2019/2020, breeding phenology and success was studied in 36 nests at the same site.  Birds called from their burrows from mid-September, laying started in early October, and the first chick was observed on 20 December.  Hatching peaked in early January and chicks fledged from the end of February to mid-March.  This breeding phenology is similar to that at the neighbouring Crozet Archipelago.  Overall nest survival was 46.4 ± 9.2% (mean ± SE; 95% CI: 29.5–64.1%), with most failures happening around hatching time.   Further monitoring is needed to assess whether introduced House Mice Mus musculus contributed to the low hatching success.  Common Diving Petrels were discovered breeding in other coastal areas, mostly in the south and east of the island. It is unlikely that breeding by this species was overlooked for three decades, suggesting that the elimination of cats allowed Common Diving Petrels to recolonise the island.”

Recolonisation naturelle de l’île subantarctique Marion par le Puffinure plongeur Pelecanoides urinatrix

Il est notoirement reconnu que les oiseaux de mer qui nichent la nuit dans des terriers sont difficiles à étudier et peuvent passer inaperçus pendant des années dans les régions éloignées. L’une de ces espèces est le Puffinure plongeur Pelecanoides urinatrix, qui a une distribution de reproduction circumpolaire dans l’océan austral, comprenant les îles subantarctiques du Prince-Edouard. Sur l’île de Marion, la plus grande des deux îles, cette espèce a été extirpée par des chats introduits en 1948. Les chats ont été complètement éradiqués en 1991 et au cours du mois d’avril 2015, des Puffinures plongeurs ont été découverts dans des terriers situés dans d’épaisses touffes d’herbes Poa cookii (tussock) de la zone côtière, sur une pente raide orientée au sud de la baie de Goodhope. Des recherches complémentaires menées en octobre 2015 et février 20216 ont confirmé la zone de reproduction sur une superficie d’environ 1 ha. La phénologie et le succès de reproduction de 36 nids localisés sur le même site ont été étudiés sur la période 2019-2020. Les oiseaux ont crié depuis leur terrier à partir de mi-septembre, la ponte a commencé début octobre et le premier poussin a été observé le 20 décembre. Le pic d’éclosion a eu lieu début janvier et les poussins se sont envolés de fin février à mi-mars. Cette phénologie de reproduction est similaire à celle observée sur l’archipel voisin de Crozet. Le taux de survie globale des nichées était de 46.4 ± 9.2% (σ; IC95%: 29.5–64.1%), la plupart des échecs se produisant autour de la période d’éclosion. Une surveillance complémentaire est nécessaire pour estimer si les souris domestiques Mus musculus introduites jouent un rôle dans le faible succès d’éclosion. Des zones de reproduction du Puffinure plongeur ont été découvertes dans d’autres zones côtières, principalement au sud et à l’est de l’île. Il est peu probable que la reproduction de cette espèce ait été négligée pendant trois décennies, ce qui laisse supposer que l’élimination des chats a permis au Puffinure plongeur de recoloniser l’île.

With thanks to Maëlle Connan and Stefan Schoombie..

Reference:

Connan, M., Schoombie, S., Schoombie, J., Dilley, B. & Ryan, P.G. 2022.  Natural recolonisation of sub-Antarctic Marion Island by Common Diving Petrels Pelecanoides urinatrix.  Ostrich doi.org/10.2989/00306525.2022.2150706.

John Cooper, ACAP News Correspondent, 20 December 2022