The South Georgia Habitat Trust has this month published issue No. 23 of its newsletter Project News which informs on progress with Phase 3 of the South Georgia Habitat Restoration Project that aims to rid South Georgia (Islas Georgias del Sur)* of its introduced rats and mice.

In the newsletter information is given on the team for Phase 3 (once more to include veteran helicopter pilot, Peter Garden and also Keith Springer who led the successful operation to rid Australia’s Macquarie Island of its introduced mammals).  Plans to treat the remaining southern third of the island of over 360 km² with 4000 bags of poison bait to be dropped from three helicopters are outlined.

South Georgia (Islas Georgias del Sur)* from Prion Island, photograph by Anton Wolfaardt

Meanwhile the following news released by the trust earlier this week is suggestive of a successful Phase 2 operation.

“News just in of the discovery of the first South Georgia Pipit [Anthus antarcticus] nest in an area cleared of rodents by the Habitat Restoration Project.  The nest was spotted at Schlieper Bay on the South coast of the North-West baiting zone at Weddell Point.  This area was treated in May 2013 as part of Phase 2 of the project.  The nest, containing five chicks, was discovered by none other than Sally Poncet, a former member of Team Rat and expert on the wildlife of South Georgia.  This thrilling news shows the rapid impact of the Habitat Restoration Project on this potentially endangered species.”

Click here to access previous newsletters of the South Georgia Habitat Restoration Project.

It is expected that removal of the island’s rodents will lead to improved breeding by its seabirds, especially burrowing petrels, which include the ACAP-listed White-chinned Petrel Procellaria aequinoctialis.

White-chinned Petrels displaying, photograph by Ben Phalan

John Cooper, ACAP Information Officer, 17 January 2015

*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.

Filipe Ceia (Department of Life Sciences, Marine and Environmental Research Centre, University of Coimbra, Portugal) and colleagues have published in the journal Oecologia on aspects of foraging by Cory’s Shearwaters Calonectris borealis.

The paper’s abstract follows

“Breeding seabirds are central-place foragers and therefore exploit food resources most intensively nearer their colonies.  When nesting aggregations are close to one another density-dependent competition is likely to be high, potentially promoting foraging segregation (i.e. neighbouring colonies may segregate to search for food in different areas).  However, little is known about spatial segregation in foraging behaviour between closely adjacent colonies, particularly in species that are wide-ranging foragers.  Here, we tested for foraging segregation between two sub-colonies of a wide-ranging seabird, Cory’s shearwater Calonectris borealis, separated by only 2 km, on a small Island in the North Atlantic.  During the 2010 chick-rearing period, 43 breeding adults of both sexes were simultaneously sampled at both sub-colonies.  A GPS logger was deployed on each individual and removed after several foraging trips at sea.  Blood samples (plasma and red blood cells) were collected from each tracked individual for stable isotope analysis.  Results indicated partial spatial segregation between the two sub-colonies during local foraging trips (i.e. those of ≤1 day duration and 216 km from the colony) accounting for 84.2 % of all trips recorded.  The location of the breeding sub-colony influenced the direction of travel of birds during local trips resulting in sub-colony-specific foraging areas.  Although the oceanographic conditions associated with the foraging range of the two sub-colonies differed, no differences were found in the habitat exploited and in their estimated diets.  This suggests that birds concentrated their feeding activity in patches of similar habitat and prey during the chick-rearing period.”

Cory's Shearwater at its breeding site, photograph by Paulo Catry

Reference:

Ceia,F.R.,  Paiva,V.H., Ceia, R.S., Hervías,S., Garthe,S., Marques, J.C. & Ramos, J.A. 2014.  Spatial foraging segregation by close neighbours in a wide-ranging seabird.  Oecologia DOI 10.1007/s00442-014-3109-1.

John Cooper, ACAP Information Officer, 16 January 2014

Peter Fretwell (British Antarctic Survey, Madingley Road, Cambridge, UK) and colleagues have published open access in the journal Remote Sensing of Environment on identifying seabird colonies by using the spectral signature of guano from satellite imagery.

The paper’s abstract follows:

“Despite the threats faced by seabirds in both terrestrial and marine habitats, even basic knowledge of the locations of colonies, population sizes and trends is lacking for many remote areas of the world.  Recent studies have shown that the guano of Adélie penguins can be identified from Landsat Enhanced Thematic Mapper (ETM) imagery and used to map colonies on coasts around continental Antarctica.  Our study highlights a new technique based on the unique spectral signature of guano that can be used to discriminate seabird colonies from background geology and vegetation in a wider range of natural environments, including the vegetated and zoologically-diverse region of the Antarctic Peninsula; moreover, the method was effective for all densely colonial, surface-nesting seabirds.  Using Landsat ETM imagery, we correctly identified all known seabird colonies of over 50 pairs in the area of Marguerite Bay.  Almost all other areas with a similar spectral signature that were outside known breeding areas were single pixels that were readily distinguishable from genuine colonies. If these were excluded, only 4.1% of pixels appeared to represent unknown breeding or roosting sites, and warrant further investigation.  The spatial extent of the guano provided a general guide to the number of individuals present, but further work would be required to determine the accuracy of this method for estimating population size.  Spectral profiles of guano collected by satellite and hand-held spectrometers were compared with available data in spectral libraries and did not match with any known geological profile.  There may also be potential for discriminating colonies of different species that differ in phenology and show seasonal changes in diet by the carefully-timed acquisition of suitable satellite imagery.  We conclude that the remotely-sensed guano signature is a good indicator of the location of seabird breeding or roosting sites, with potentially wide application to other areas of the world.”

Southern Giant Petrel in Antarctica, photograph by Michael Dunn

Click here for a news story on the research.

Reference:

Fretwell, P.T., Phillips, R.A., Brooke, M.deL., Fleming, A.H. & McArthur, A. 2015.  Using the unique spectral signature of guano to identify unknown seabird colonies.  Remote Sensing of Environment 156: 448-456.

John Cooper, ACAP Information Officer, 15 January 2015

Leandro Bugoni (College of Medical, Veterinary and Life Sciences, University of Glasgow, UK) and colleagues have published in the journal Antarctic Science on moult of three procellariiform species in the south-west Atlantic off Brazil.

The paper’s abstract follows:

“Primary, tail and body moult of three seabirds from Tristan da Cunha archipelago were studied by castnetting offshore south Brazil from February 2006 to August 2007.  Timing, duration and synchronization of primary and tail moult are described relative to the annual calendar.  Body moult overlapped breeding in Atlantic yellow-nosed albatrosses (Thalassarche chlororhynchos), but tail and primary moult did not.  Spectacled petrels (Procellaria conspicillata) had protracted body moult, whereas primary and tail moult were completed by August.  We documented onset of primary moult during chick-rearing in spectacled petrels and great shearwaters (Puffinus gravis) of unknown breeding status, and suggest that the south-west Atlantic Ocean holds important numbers of moulting birds of both species during the summer–early autumn. The albatrosses and the spectacled petrels replaced rectrices alternately. Great shearwaters replaced rectrices outward, starting at the central pair.  Primary, tail and body moult largely overlap in all three species, suggesting that the metabolic costs of primary moult may not be overly restrictive.  Metabolic and nutritional ability to afford simultaneous moult of different feather tracts support the idea that impaired flight caused by wing moult is a strong factor driving no overlap of primary moult and breeding.”

Atlantic Yellow-nosed Albatross, photograph by Peter Ryan

Reference:

Bugoni, L., Naves, L.C.& Furness, R.W. 2015.  Moult of three Tristan da Cunha seabird species sampled at sea.  Antarctic Science doi.org/10.1017/S0954102014000583.

John Cooper, ACAP Information Officer, 14 January 2015