Australia’s World Heritage-listed Macquarie Island has been formally declared free of all alien mammals this week after a near-seven-year campaign to eradicate European Rabbits Oryctolagus cuniculus, Black Rats Rattus rattus and the House Mouse Mus musculus by the Macquarie Island Pest Eradication Programme (MIPEP).  This news follows the earlier eradication of feral Domestic Cats Felis catus from the island.

In 2007, the Australian Federal and Tasmanian Governments jointly funded an AUS$25 million project to eradicate introduced pests from the 12 785-ha island, utilizing poison bait dropped by helicopters followed by hunting with specially-trained dogs.  No pets have been detected for the past two years and the eradication effort has been declared a success.

A Macquarie Island view, photograph by Aleks Terauds 

Project Manager Keith Springer stated to the media: "We've had teams that have scoured the island by day and by night, covering a total of 92,000 km on the island, in terms of their tracked travel, searching every nook and cranny that they could access, to make sure that there's none left, no rabbit and no rodent” (click here).  The latest team and their dogs have now returned from “Macca” to Hobart in Tasmania where they received commemorative dog tags recognizing their contribution in an awards presentation. The hunters got a badge.

The Macca dogs get their tags in Hobart, photograph by Justine Shaw

Macquarie Island is now the World’s largest island by far from which House Mice have been eradicated.  The previous record was New Zealand’s linked Motutapu and Rangitoto Islands at a combined area of 3800 ha (click here).  This success has significant implications for (and offers encouragement towards) plans to eradicate mice on the smaller islands of Gough (6400 ha) in the South Atlantic and Antipodes (2025 ha) south of New Zealand.

With a pest-free Macca now a reality, biosecurity measures for all shipping to the island have been improved in a joint programme between the Australian Antarctic Division and the Tasmanian Parks and Wildlife Service.

Read the official press release on MIPEP's sucess here.

Click here for previous coverage in ACAP Latest News of the eradication effort on Macquarie Island.

With thanks to Justine Shaw, Keith Springer and Aleks Terauds for information and the photographs.

John Cooper, ACAP Information Officer, 09 April 2014

Sebastián Jiménez (Laboratorio de Recursos Pelágicos, Dirección Nacional de Recursos Acuáticos, Montevideo, Uruguay) and colleagues have published in the journal Biological Conservation on four species of great albatrosses Diomedea spp. killed by longliners in waters off Uruguay in the south-west Atlantic Ocean.

The paper’s abstract follows:

“Pelagic longline fisheries in the southwest Atlantic are a major conservation concern for several threatened seabirds, including four species of great albatrosses: wandering albatross (Diomedea exulans), Tristan albatross (Diomedea dabbenena), southern royal albatross (Diomedea epomophora) and northern royal albatross (Diomedea sanfordi).  The aim of this study was to examine the spatial and temporal variation in bycatch rates of these species, and to identify the contributing environmental and operational factors.  We used data collected by observers on board pelagic longliners in the Uruguayan fleet in 2004–2011, and on Japanese vessels operating in Uruguay under an experimental fishing license in 2009–2011.  Bycatch rates for northern and southern royal albatrosses were higher than expected based on previous reports, particularly over the shelf break.  Wandering and Tristan albatrosses were caught predominantly in pelagic waters, where there are numerous fishing fleets from other flag states.  Bycatch of great albatrosses was highest in April–November, with the peak for royal albatrosses in June–July, and for wandering and Tristan albatrosses in September–November.  A range of vessel operational practices and habitat variables affected bycatch rates, among which setting time, moon phase, area and season are useful in terms of risk assessment, and in the development and improvement of conservation measures for these highly threatened species.”

Colour-banded Tristan Albatross from Gough Island off Uruguay

Photograph by Martin Abreu

With thanks to Barry Baker for information.

Reference:

Jiménez, S., Phillips, R.A.,  Brazeiro, A.,  Defeo, O. & Domingo, A. 2014.  Bycatch of great albatrosses in pelagic longline fisheries in the southwest Atlantic: contributing factors and implications for management.  Biological Conservation 171: 9-20.

John Cooper, ACAP Information Officer, 8 April 2014

Sandra Hervías (Animal Health Department, University of Murcia, Spain) and colleagues write in the journal Zoology on Black Rats Rattus rattus preying upon Cory’s Shearwaters Calonectris borealis in the presence of feral cats Felis catus.

The paper’s abstract follows:

“This study assessed the impact of introduced black rats on Cory's shearwater (Calonectris diomedea borealis) in a multi-invaded insular ecosystem where rats are mesopredators.  We hypothesized that black rats should have little impact on Cory's shearwaters in the presence of cats as superpredators.  Stomach contents and stable isotope analysis (SIA) in tissues of black rats were analyzed to assess the trophic ecology and the importance of Cory's shearwater in their diet.  We also studied the isotopic signature of mouse tissues to confirm previous data showing no predation of this species on Cory's shearwaters.  For both rodent species, temporal variation in diet composition in response to the availability of seabird prey was evaluated, and short- and long-term consistency in diet was tested using different tissues from the same individual.  For black rats a Bayesian isotope mixing model (SIAR) was applied to determine the relative contribution of each prey to the individual diet.  SIA of mouse tissues varied between the Cory's shearwater breeding and non-breeding periods.  However, no significant differences were found in diet and SIA for black rats.  In contrast, individuals of both species showed a strong consistency in diet which apparently benefited their body condition index.  Although black rats supplement their diet with Cory's shearwater eggs and chicks (8.3% in stomach contents and 10.6% in the SIAR model), their current impact on the Cory's shearwater population appears to be small, probably due to several factors including the small size of the rat population and a high level of rat predation by cats.”

Cory's Shearwaters, photograph by Paulo Catry

Reference:

Hervías, S, Ceia, F.R., Pipa, T., Nogales, M., Ruiz de Ybáñez, R. & Ramos, J.A. 2014.  How important are seabirds in the diet of black rats on islands with a superpredator?  Zoology  doi.org/10.1016/j.zool.2013.12.003.

John Cooper, ACAP Information Officer, 07 April 2014

One of the USA’s Northwestern Hawaiian Islands (NHWI) in the North Pacific, Laysan Island is a raised coral atoll with a central 70-ha hypersaline lake.  Its area is about 4 km² (1.6 by 2.4 km); it is one of the largest islands in the NHWI chain.  The atoll is low-lying with a maximum height of 15 m and is partially covered with a low vegetation of grasses and vines; parts are exposed sand with little growth.  The island is inhabited year round by a field camp operated by researchers and managers.

 Two aerial views of Laysan Island with its central lake

The single coconut grove with Laysan Albatrosses, photograph by Greg McClelland

Low grassy vegetation, photograph by Greg McClelland

The northern "sand desert", photograph by Greg McClelland

Laysan falls within the Papahanaumokuakea Marine National Monument, a large Marine Protected Area declared in 2006.  In 2010 Papahanaumokuakea became one of then only 28 mixed (cultural and natural) UNESCO World Heritage Sites in the World.

Two ACAP-listed species, the Laysan Phoebastria immutabilis and Black-footed P. nigripes Albatrosses breed on the atoll.  The ACAP Data Portal gives 2012 populations of 134 835 breeding pairs of Laysan and 24 565 pairs of Black-footed Albatrosses.

Laysan Albatrosses breeding and displaying on Laysan Island

Photographs by Mark Rauzon

 Black-footed Albatross chicks cool off with an inquisitive Laysan Finch

Photograph by Mark Rauzon

Other procellariiform species that occur are the Bonin Petrel Pterodroma hypoleuca, Buler’s Petrel Bulweria bulwerii, Christmas Puffinus nativitatus and Wedge-tailed P. pacificus Shearwaters and Tristram’s Storm Petrel Oceanodroma tristrami, along with and a number of other seabird species.  Occasional singleton Short-tailed Albatrosses P. albatrus have been recorded ashore on Laysan (click here); with an adult photographed in 2011 (click here).  Breeding attempts have not (as yet) been reported, unlike on Kure and Midway Atolls in the Northwestern Hawaiian Islands.

Laysan was severely altered by the effects of feral European Rabbits Oryctolagus cuniculus.  Brought as a food source for humans in 1903, the rabbits ate nearly all of the island's plants, leading to wind erosion of exposed sand and driving to extinction three land bird taxa.  Albatrosses were also heavily exploited for their feathers, eggs and guano around this time, leading to massive mortality.

The degradation of Laysan Island led to the creation of the Hawaiian Islands Bird Reservation by President Theodore Roosevelt in 1909.  In recent years successful efforts by the U.S. Fish and Wildlife Service have eliminated most pests, such as Polynesian Rats Rattus exulans, the rabbits (believed absent since 1923), and weeds, and restored much of the native vegetation on the island with translocations and plantings.  As a result, Laysan Duck Anas laysanensis and Laysan Finch Telespiza cantans populations are increasing and the Millerbird Acrocephalus familiaris has been reintroduced (click here).  This good news is tempered by the risk Laysan (and all the low-lying NWHI islands) face from impending sea-level rise, as well as from storms and tsunamis.

An adult Short-tailed Albatross turns up on Laysan Island (click here)

With thanks to Greg McClelland and Mark Rauzon for their photographs and information.

Selected Literature:

Arata, J.A., Sievert, P.R. & Naughton, M.B. 2009.  Status Assessment of Laysan and Black-footed Albatrosses, North Pacific Ocean, 1923-2000.  U.S. Geological Survey Scientific Investigations Report 2009-5131.  Reston: U.S. Geological Survey.

Cousins, K. & Cooper, J. 2000.  The Population Biology of the Black-footed Albatross in Relation to Mortality caused by Longline Fishing.  Honolulu: Western Pacific Regional Fishery Management Council.

Ely, C.A. & Clapp, R.B. 1973.  The natural history of Laysan Island, Northwestern Hawaiian Islands.  Atoll Research Bulletin No. 171.  361 pp.

Frierson, P. 2012.  The Last Atoll.  Exploring Hawai’i’s Endangered Ecosystems.  San Antonio: Trinity University Press.  309 pp.

Harrison, C.S. 1990.  Seabirds of Hawaii:  Natural History and Conservation.  Ithaca: Cornell University Press. 249 pp.

McClelland, G.T.W., Jones, I.L., Lavers, J.L. & Sato, F. 2008.  Breeding biology of Tristram's Storm-petrel Oceanodroma tristrami at French Frigate Shoals and Laysan Island, Northwest Hawaiian Islands.  Marine Ornithology 36: 175-181.

Naughton, M.B., Romano, M.D. & Zimmerman, T.S. 2007.  A Conservation Action Plan for Black-footed Albatross (Phoebastria nigripes) and Laysan Albatross (P. immutabilis).  Version 1.0.

Pyle, R.L. & Pyle, P. 2009.  The Birds of the Hawaiian Islands: Occurrence, History, Distribution, and Status.  Version 1.  Honolulu: B.P. Bishop Museum.

Rauzon, M. J. 2001.  Isles of Refuge.  Wildlife and History of the Northwestern Hawaiian Islands.  Honolulu: University of Hawai'i Press.  205 pp.

Storlazzi, C.D., Berkowitz, P., Reynolds, M.H. & Logan, J.B. 2013.  Forecasting the Impact of Storm Waves and Sea-level Rise on Midway Atoll and Laysan Island within the Papahānaumokuākea  Marine National Monument - a Comparison of Passive versus Dynamic Inundation Models.  U.S. Geological Survey Open-File Report 2013-1069.  78 pp.

John Cooper, ACAP Information Officer, 06 April 2014