Rocío Moreno (British Antarctic Survey, Cambridge, UK) and colleagues have published in the Journal of Animal Ecology on the trophic structure of a sub-Antarctic seabird community over time.

The paper’s summary follows:

1. Understanding interspecific interactions, and the influences of anthropogenic disturbance and environmental change on communities, are key challenges in ecology.  Despite the pressing need to understand these fundamental drivers of community structure and dynamics, only 17% of ecological studies conducted over the past three decades have been at the community level.
2. Here, we assess the trophic structure of the procellariiform community breeding at South Georgia, to identify the factors that determine foraging niches and possible temporal changes.  We collected conventional diet data from 13 sympatric species between 1974 and 2002, and quantified intra- and inter-guild, and annual variation in diet between and within foraging habits.  In addition, we tested the reliability of stable isotope analysis (SIA) of seabird feathers collected over a 13-year period, in relation to those of their potential prey, as a tool to assess community structure when diets are diverse and there is high spatial heterogeneity in environmental baselines.
3. Our results using conventional diet data identified a four-guild community structure, distinguishing species that mainly feed on crustaceans; large fish and squid; a mixture of crustaceans, small fish and squid; or carrion.  In total, Antarctic krill Euphausia superba represented 32%, and 14 other species a further 46% of the combined diet of all 13 predators, underlining the reliance of this community on relatively few types of prey.  Annual variation in trophic segregation depended on relative prey availability; however, our data did not provide evidence of changes in guild structure associated with a suggested decline in Antarctic krill abundance over the past 40 years.
4. Reflecting the differences in δ15N of potential prey (crustaceans vs. squid vs. fish and carrion), analysis of δ15N in chick feathers identified a three-guild community structure that was constant over a 13-year period, but lacked the trophic cluster representing giant petrels which was identified using conventional diet data.
5. Our study is the first in recent decades to examine dietary changes in seabird communities over time.  Conventional dietary analysis provided better resolution of community structure than SIA.  However, δ15N in chick feathers, which reflected trophic (level) specialization, was nevertheless an effective and less time-consuming means of monitoring temporal changes.

Wandering Albatross, photograph by Linda Clokie

Reference:

Moreno, R., Stowasser, G., McGill, R.A.R, Bearhop, S.& Phillips, R.A.2015.  Assessing the structure and temporal dynamics of seabird communities: the challenge of capturing marine ecosystem complexity.  Journal of Animal Ecology DOI: 10.1111/1365-2656.12434.

John Cooper, ACAP Information Officer, 11 October 2015

The Vulnerable Pink-footed Shearwater Puffinus creatopus is the most recent addition to the ACAP “family”, having been listed in May this year (click here).  A breeding endemic to Chile, it migrates to the northern hemisphere as far as Canadian waters after breeding.  Over recent years the species’ trans-equatorial migration route along the eastern Pacific seaboard has been studied by the use of solar-powered satellite transmitters.  Ten transmitters were placed on breeding Pink-footed Shearwaters in April this year on Isla Mocha in Chile (click here).

Pink-footed Shearwater, photograph by Peter Hodum

The tagged shearwaters are now heading home to Chile after their trans-equatorial sojourn.  One satellite-tagged bird has flown nearly 21 000 kilometres in total during its migration so far, and is currently heading south (orange dots) toward its breeding site on Isla Mocha.

Click here to read of the Pink-foots' progress north towards the Canadian border earlier in the year.

The tracking study is a project of the U.S. Geological Survey and Oikonos Ecosystem Knowledge.

John Cooper, ACAP Information Officer, 10 October 2015

Chilean President Michelle Bachelet has this week announced the creation of the Nazca-Desventuradas Marine Park, which will cover a surface area of more than 297 000 km² around the Islas Desventuradas (2.4-km² San Ambrosio and 2.5-km² San Félix Islands) c. 900 km west of the Chilean mainland.  President Bachelet announced the Nazca-Desventuradas Marine Park at the Our Ocean Conference 2015 in Valparaiso, Chile earlier this week.  The first Our Ocean Conference was held in Washington, D.C., USA in June of last year.

The two islands form part of the underwater Nazca Ridge, which runs south-west from Peru towards Easter Island.  With the formation of the Nazca-Desventuradas Marine Park, Chile will now protect 12 percent of its marine surface area.  The islands are uninhabited save for a Chilean naval detachment and the intermittent presence of lobster fishers; feral cats Felis catus (to San Félix) and rodents have been introduced.  Access to the Islas Desventuradas is restricted due to the presence of the naval base on San Félix – which has a runway for aeroplanes.

The Nazca-Desventuradas Marine Park

The Desventuradas support breeding populations of two gadfly petrels (Kermadec Pterodroma neglecta and Vulnerable Masatierra P. defilippiana) and White-bellied Storm Petrel Fregetta grallaria, amongst other seabirds.  ACAP-listed Black-browed Thalassarche melanophris and Salvin’s T. salvini Albatrosses and Southern Giant Petrels Macronectes giganteus have been regularly recorded in their surrounding waters.

Southern Giant Petrels have been reported from around the Islas Desventuradas, photograph by Warwick Barnes

The new marine park is to be a fully protected no-take zone where fishing and other extractive activities will not be allowed, although an artisanal trap fishery for Juan Fernández Rock Lobster Jasus frontalis, which has been certified as sustainable by the Marine Stewardship Council, will continue in specific areas around the islands.

The Chilean Government has also committed to the creation of a Marine Park around Easter Island (Rapa Nui) encompassing more than 600 000 km², pending the approval of the island’s indigenous community. Easter Island supports breeding populations of three gadfly petrels and a shearwater.  In addition, Chile intends to protect part of the waters around Juan Fernandez (Robinson Crusoe) Island with a network of five no-take zones as a marine park.

Proposed Easter Island Marine Park

News item researched from here and from several other on-line sources.

The Our Ocean Conference will return to the USA in 2016.

Reference:

Flores, M.A., Schlatter, R.P. & Hucke-Gaete, R. 2014.  Seabirds of Easter Island, Salas y Gómez Island and Desventuradas Islands, southeastern Pacific Ocean.  Latin American Journal of Aquatic Research 42: 752-759.

John Cooper, ACAP Information Officer, 09 October 2015

Following a review in 2013 by BirdLife International’s Globally Threatened Seabird Forum it was considered that “despite considerable uncertainty over the trend data, an uplisting from Vulnerable to Endangered [of the ACAP-listed White-chinned Petrel Procellaria aequinoctialis] may be warranted”.  However, no conclusion was then reached and the review was kept open until this year (click here).

Following further comments by interested individuals and organizations, including by the ACAP Secretariat, BirdLife has now recommended that the White-chinned Petrel - at risk to longline fisheries in the Southern Ocean and in waters off southern Africa and South America - retain its Vulnerable status and not be uplisted to Endangered.

White-chinned Petrel on the Antipodes, photograph by David Boyle

“The final categorisation will be published on the BirdLife website in late October and on the IUCN website in November, following further checking of information relevant to the assessment by BirdLife and IUCN.”

John Cooper, ACAP Information Officer, 08 October 2015