Milton Avalos (Marine and Environmental Sciences Centre, Department of Life Sciences, University of Coimbra, Portugal) and colleagues write in the journal Marine Biology on changes in the foraging distribution of Cory’s Shearwaters Calonectris borealis in relation to changes in marine productivity.

The paper’s abstract follows:

“Seabirds due to their status as sentinels of the marine environment can indicate qualitative changes at various levels of the food web. Furthermore, changes in marine productivity have been correlated with fluctuations in large-scale atmospheric conditions driven by global indices, such as the North Atlantic Oscillation (NAO) index. During the winter of 2009/2010, the second lowest NAO index in history was recorded leading to detrimental conditions that influenced productivity levels in the northeast Atlantic. The response of the Cory’s Shearwater Calonectris borealis, during the period of ameliorating climatic conditions from this drastic event, was monitored in two islands with contrasting productivity patterns: Berlenga, located on the rich upwelling area of the Portuguese shelf; and Cima Islet (Porto Santo Island), located in a poor oceanic environment in the Madeira Archipelago. We collected a multi-year GPS-tracking data set (2011–2015) from adult breeders during the chick-rearing season to examine their at-sea foraging distribution. During a year of low productivity, kernel estimations demonstrated that Cima Islet birds expanded their home ranges and core foraging areas all over the northeast Atlantic, whereas Berlenga birds maintained their distribution close to the breeding colony. Once oceanographic conditions ameliorated from 2012 to 2015, birds decreased significantly their foraging effort, and oceanic breeders concentrated their activity closer to the breeding colony. Analysis of habitat use by means of Maximum Entropy Modelling confirmed distance-to-colony as the most important predictor in the distribution of Cory’s Shearwater. Environmental variables describing sea surface temperature, bathymetry, and chlorophyll a were more influential in Porto Santo, indicating higher sensitivity of the oceanic population to marine productivity proxies. Our study confirms that the Cory’s Shearwater possesses enormous flexibility in its foraging tactics and that neither oceanic nor neritic populations disperse randomly from their breeding colonies to the open ocean even under conditions of environmental stochasticity. Instead, populations breeding in contrasting environments vary in their responses according to their strategies and to the changing levels of marine productivity in the surroundings of their colonies.”

Cory's Shearwaters, photograph by Paulo Catry

Reference:

Avalos, M.R., Ramos, J.A., Soares, M., Ceia, F.R., Fagundes, A.I., Gouveia, C., Menezes, D. & Paiva, V.H. 2017.  Comparing the foraging strategies of a seabird predator when recovering from a drastic climatic event. Marine Biology 164: 48.  doi:10.1007/s00227-017-3082-4.

John Cooper, ACAP Information Officer, 20 March 2017

Airam Rodríguez (Research Department, Phillip Island Nature Parks, Cowes, Australia) and colleagues have published in the Journal of Wildlife Management on the condition of beach-washed and artificial light-downed Short-tailed Shearwater Ardenna tenuirostris fledglings.

The paper’s abstract follows:

One of the most critical phases in the life of petrels (Procellariiformes) is at fledging when young birds pass from parental dependence on land to an independent life at sea. To mitigate mortality at this time, rescue programs are implemented near breeding sites around the world, especially for birds grounded by artificial lights. We evaluated the plumage and body condition of short-tailed shearwater (Ardenna tenuirostris) fledglings captured at colonies just before departure in comparison to fledglings washed up on beaches and to fledglings attracted by artificial light along roads. We measured abundance of down, body mass, and body condition index as the standardized residuals of a regression of body mass on size, and employed linear models to test differences on body mass and body condition between locations. Beach-washed birds were underweight and in poor condition, suggesting their future survival probabilities at sea were low. Birds rescued on roads as a consequence of light attraction had lower body weights and condition indices than fledglings captured at the colony. However, more than 50% of light-attracted birds had attained similar weights to those of adults, suggesting they have higher probabilities of survival than beach-washed birds. Water-logged birds being washed onto beaches is a natural process, but birds grounded by lighting along roads is an increasing anthropogenic threat that requires management. Thus, management and conservation efforts should be directed to protect birds in the colonies and reduce light-induced mortality, ideally through the strategic reduction of light sources and lateral light spillage. When resources for conservation are limited, rescue programs should focus on rescuing birds from roads rather than beach-washed birds, which have a lower probability of survival.”

Short-tailed Shearwater, photograph by Mark Carey

Reference:

Rodríguez, A., Moffett, J., Revoltós, A., Wasiak, P., Mcintosh, R.R, Sutherland, D.R., Renwick, l., Dann, P. & Chiaradia, A. 2017.  Light pollution and seabird fledglings: Targeting efforts in rescue programs.  Journal of Wildlife Management DOI: 10.1002/jwmg.21237.

John Cooper, ACAP Information Officer, 17 March 2017

Australia is calling for public comment on the draft update to its Threat Abatement Plan 2014 for the Incidental Catch (or Bycatch) of Seabirds during Oceanic Longline Fishing Operations.

A Black-browed Albatross feeds its downy chick on Australia's Heard Island

“The draft threat abatement plan for incidental catch of seabirds provides a national strategy to guide the activities of government, industry and research organisations in abating the impact of oceanic longline fishing operations on seabirds in Commonwealth fisheries.”

The consultation paper and related documents are available on the Department of the Environment and Energy website here.  The public consultation period is open until 30 June 2017.

Further information about the 2014 abatement plan is available at the Threat Abatement Plan – seabirds page.

With thanks to Jonathon Barrington, Australian Antarctic Division, for information.

John Cooper, ACAP Information Officer, 16 March 2017

"Snow birds" by Rebekah White in the New Zealand Geographic is a good read.  Just click here.

Hutton's Shearwater

Read earlier postings to ACAP Latest News on New Zealand's endemic and globally Endangered Hutton's Shearwater Puffinus huttoni.  Click here for two ALN postings on the likely effects of the November 2016 earthquake on the bird's two mountain breeding sites.

John Cooper, ACAP Infomation Officer, 15 March 2017