The Gough and Inaccessible Islands World Heritage Site is made up of two of the four Tristan islands in the South Atlantic, themselves part of the United Kingdom Overseas Territory of St Helena, Ascension and Tristan da Cunha.  Both Gough and Inaccessible (and their surrounding waters) are nature reserves and since 2008 Ramsar Wetlands of International Importance, reflecting their high conservation values.  The islands support breeding populations of six species of ACAP-listed albatrosses and petrels, including Critically Endangered Tristan Diomedea dabbenena and Endangered Atlantic Yellow-nosed Thalassarche chlororhynchos Albatrosses and the Vulnerable Spectacled Petrel Procellaria conspicillata, all endemic to the island group.

Spectacled Petrel - endemic to Inaccessible Island

Photograph by Peter Ryan

A single management plan for the World Heritage Site available on-line from the UK’s Royal Society for the Protection of Birds (RSPB) - that replaced earlier individual plans for each island - has now been joined by a series of 19 appendices that include a Description and Resource Inventory, Management Policies and Prescription Guidelines, applicable legislation and a Scientific and Historical Bibliography, along with species lists and other documents (click here).

Reference:

RSPB and Tristan da Cunha Government 2010.  Gough and Inaccessible Islands World Heritage Site Management Plan April 2010 – March 2015.  32 pp. & 19 Appendices.

With thanks to Clare Stringer for information.

John Cooper, ACAP Information Officer, 01 June 2014

Catharine Horswill (British Antarctic Survey, Cambridge, UK) and colleagues have published open access in the Journal of Animal Ecology on how giant petrels Macronectes spp. may be causing declines in numbers of Macaroni Penguins Eudyptes chrysolophus.

The paper’s summary follows:

1. Understanding the demographic response of free-living animal populations to different drivers is the first step towards reliable prediction of population trends.
2. Penguins have exhibited dramatic declines in population size, and many studies have linked this to bottom-up processes altering the abundance of prey species.  The effects of individual traits have been considered to a lesser extent, and top-down regulation through predation has been largely overlooked due to the difficulties in empirically measuring this at sea where it usually occurs.
3. For 10 years (2003–2012), macaroni penguins (Eudyptes chrysolophus) were marked with subcutaneous electronic transponder tags and re-encountered using an automated gateway system fitted at the entrance to the colony.  We used multistate mark–recapture modelling to identify the different drivers influencing survival rates and a sensitivity analysis to assess their relative importance across different life stages.
4. Survival rates were low and variable during the fledging year (mean = 0·33), increasing to much higher levels from age 1 onwards (mean = 0·89).  We show that survival of macaroni penguins is driven by a combination of individual quality, top-down predation pressure and bottom-up environmental forces.  The relative importance of these covariates was age specific.  During the fledging year, survival rates were most sensitive to top-down predation pressure, followed by individual fledging mass, and finally bottom-up environmental effects.  In contrast, birds older than 1 year showed a similar response to bottom-up environmental effects and top-down predation pressure.
5. We infer from our results that macaroni penguins will most likely be negatively impacted by an increase in the local population size of giant petrels.  Furthermore, this population is, at least in the short term, likely to be positively influenced by local warming.  More broadly, our results highlight the importance of considering multiple causal effects across different life stages when examining the survival rates of seabirds.

A Southern Giant Petrel kills a penguin at sea, photograph by Peter Ryan

Reference:

Horswill, C., Matthiopoulos, J., Green, J.A., Meredith, M.P., Forcada, J., Peat, H., Preston, M., Trathan, P.N. & Ratcliffe, N. 2014.  Survival in macaroni penguins and the relative importance of different drivers: individual traits, predation pressure and environmental variability.  Journal of Animal Ecology DOI: 10.1111/1365-2656.12229.

John Cooper, ACAP Information Officer, 31 May 2014

In recent seasons the Patagonian Toothfish Dissostichus eleginoides longline fishery in CCAMLR Statistical Area 48.3 in the vicinity of South Georgia (Islas Georgias del Sur*) has commenced a few days earlier each year.  The benefits of starting earlier include the chance of safer conditions at sea.  After many years of negligible bycatch of seabirds in this fishery one vessel has reported catching 74 ACAP-listed White-chinned Petrels Procellaria aequinoctialis on a single longline set on 16 April this year.

In the early years of this fishery in the 1990s large numbers of albatrosses and petrels were killed and as a consequence the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) introduced a number of measures to reduce the bycatch, including limiting the fishing season to winter months, restricting the setting of lines to darkness, ensuring lines sink quickly and enforcing the use of bird-scaring lines, resulting in a reduction of bird bycatch to close to zero.  Following the introduction of these measures the fishery achieved Marine Stewardship Council certification.

A hooked White-chinned Petrel, photograph by Nicolas Gasco

Because of this success CCAMLR has, since 2010, approved an earlier start date for the season that has been incrementally and experimentally brought forward by five days each year.  The incidental catch of White-chinned Petrels occurred on a line set during this experimental extension period.  Mitigation measures in the fishery have now been adjusted so that vessels complete the setting of lines at least three hours before sunrise until 15 May to reduce the risk of incidental capture of any more White-chinned Petrels.

Report adapted from Penguin News, 25 April 2014.

With thanks to Sally Poncet for information.

John Cooper, ACAP Information Officer, 30 May 2014

*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.

SAFRING Metal band 9A 69153 was placed on a Southern Giant Petrel Macronectes giganteus chick in the monitoring colony below Low Hump on Gough Island’s west coast on 30 November 2013.  On 18 May this year Josã Carlos Alonso Ruibal reported the bird to the South African Bird Ringing Unit as having been found dead on Karekare Beach, 35 km west of Auckland on New Zealand’s North Island 169 days after banding (click here).  The date of actual fledging of the chick is not known although it was still present at its nest site on 18 December 2013.

Juvenile Southern Giant Petrels are known to undertake large movements from their breeding grounds.  In contrast adults breeding at Gough appear to stay in the South Atlantic.

A Southern Giant Petrel chick on Gough Island, photograph by Michelle Steenkamp

Perhaps related to this recovery is that the New Zealand Bird Rescue Charitable Trust based in Auckland has this month taken into care three Northern Giant Petrels M. halli.  The trust comments it is unusual to have as many as three at a time.  Photographs posted to the trust’s Facebook page suggest the birds are all recently fledged juveniles.  A Northern Giant Petrel brought in on 23 May is also being looked after in Ballina, New South Wales, Australia by Australian Seabird Rescue.

The three rescued Northern Giant Petrels under care in New Zealand

With thanks to Ben Dilley and Dane Paijmans for information.

Selected Literature:

Cooper, J. 1983.  Bird ringing at Gough Island, 1977-1982.  South African Journal of Antarctic Research 13: 47-48.

Cooper, J. & Parker, G.C. 2011.  Observations of sexual dimorphism among the Southern Giant Petrels Macronectes giganteus of Gough Island.  Sea Swallow 60: 84-90.

Cuthbert, R.J., Cooper, J. & Ryan, P.G. 2013.  Population trends and breeding success of albatrosses and giant petrels at Gough Island in the face of at-sea and on-land threats.  Antarctic Science 26: 163-171.

Patterson, D.L. & Hunter, S. 2000.  Giant petrel Macronectes spp. band recovery analysis from the International Giant Petrel Banding Project, 1988/89.  Marine Ornithology 28: 69-74.

John Cooper, ACAP Information Officer, 29 May 2014