Airam Rodríguez (Department of Evolutionary Ecology, Estación Biológica de Doñana, Seville, Spain) and colleagues have published in the on-line and open-access journal Scientific Reports on the effects of light pollution on fledging Cory’s Shearwater Calonectris diomedea.

The paper’s abstract follows:

“Light pollution and its consequences on ecosystems are increasing worldwide.  Knowledge on the threshold levels of light pollution at which significant ecological impacts emerge and the size of dark refuges to maintain natural nocturnal processes is crucial to mitigate its negative consequences.  Seabird fledglings are attracted by artificial lights when they leave their nest at night, causing high mortality.  We used GPS data-loggers to track the flights of Cory’s shearwater Calonectris diomedea fledglings from nest-burrows to ground, and to evaluate the light pollution levels of overflown areas on Tenerife, Canary Islands, using nocturnal, high-resolution satellite imagery.  Birds were grounded at locations closer than 16 km from colonies in their maiden flights, and 50% were rescued within a 3 km radius from the nest-site.  Most birds left the nests in the first three hours after sunset.  Rescue locations showed radiance values greater than colonies, and flight distance was positively related to light pollution levels.  Breeding habitat alteration by light pollution was more severe for inland colonies.  We provide scientific-based information to manage dark refuges facilitating that fledglings from inland colonies reach the sea successfully.  We also offer methodological approaches useful for other critically threatened petrel species grounded by light pollution.”

Cory's Shearwater fledgling downed by light pollution, photograph by Beneharo Rodríguez

Reference:

Rodríguez, A., Rodríguez, B. & Negro, J.J. 2015.  GPS tracking for mapping seabird mortality induced by light pollution.  Scientific Reports 5: 10670.  doi:10.1038/srep10670.

John Cooper, ACAP Information Officer, 08 June 2015

READ MORE ON JAMES GIBBS' FIELDWORK ON ESPANOLA HERE. 

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The response of breeding ACAP-listed Waved Albatrosses Phoebastria irrorata to large brush clearings (pistas or airstrips) created in the interior of the south side of the island of Española in the Galapagos is being assessed by James Gibbs of the State University of New York’s College of Environmental Science and Forestry (click here).

Large numbers of albatrosses breed in the interior of the island among thick vegetation.  As a consequence the birds must scramble in and out of small open areas for take-off and landing and then walk great distances through the brush to their nest sites.  It is thought that the growth of woody vegetation  may be related to the earlier eradication of feral Domestic Goats Capra aegagrus hircus on the island.

Two years ago counts were made of breeding birds in ten 50-m radius plots scattered through the island’s interior.  Every woody plant was cut by hand and removed in five of these plots.

A Waved Albatross takes off and clearing brush on Española

Last year the breeding birds were counted: the cleared areas gained five breeding albatrosses on average, the controls (uncleared plots) none.  These counts are now being repeated.

The study forms part of a larger effort by the Galapagos Conservancy to decide whether to let the island continue to recover without intervention from the ravages of 100 years plus of goat infestation, or if large-scale habitat management, which could include brush clearing, is needed to get island restoration back on track.

Española falls within the Galápagos National Park which is situated within the Galápagos Marine Reserve.  The Galápagos Islands, including Española, have been a World Heritage Site since 1978.

John Cooper, ACAP Information Officer, 07 June 2015

Rémi Fay (Centre d'Etudes Biologiques de Chizé, Villiers-en-Bois, France) and colleagues have published in the Journal of Animal Ecology on the demography of Wandering Albatrosses Diomedea exulans in their first few years of life. 

The paper’s summary follows:

“1. Our understanding of demographic processes is mainly based on analyses of traits from the adult component of populations.  Early-life demographic traits are poorly known mainly for methodological reasons.  Yet, survival of juvenile and immature individuals is critical for the recruitment into the population and thus for the whole population dynamic, especially for long-lived species.  This bias currently restrains our ability to fully understand population dynamic of long-lived species and life history theory.

2. The goal of this study was to estimate the early-life demographic parameters of a long-lived species with a long immature period (9-10 years), to test for sex and age effects on these parameters, and to identify the environmental factors encountered during the period of immaturity that may influence survival and recruitment.

3. Using capture-mark-recapture multi-event models allowing us to deal with uncertain and unobservable individual states, we analysed a long-term data set of wandering albatrosses to estimate both age and sex specific early-life survival and recruitment.  We investigated environmental factors potentially driving these demographic traits using climatic and fisheries covariates and tested for density dependence.

4. Our study provides for the first time an estimate of annual survival during the first two years at sea for an albatross species (0.801±0.014).  Both age and sex affected early-life survival and recruitment processes of this long-lived seabird species. Early-life survival and recruitment were highly variable across years although the sensitivity of young birds to environmental variability decreased with age.  Early-life survival was negatively associated with sea surface temperature and recruitment rate was positively related to both Southern Annular Mode and sea surface temperature.  We found strong evidence for density dependence mortality of juveniles.  Population size explained 41% of the variation of this parameter over the study period.

5. These results indicate that early-life survival and recruitment were strongly age and sex-dependent in a dimorphic long-lived species.  In addition, early life demographic parameters were affected by natal environmental conditions and by environmental conditions faced during the period of immaturity.  Finally, our results constitute one of the first demonstrations of density dependence on juvenile survival in seabirds, with major consequences for our understanding of population dynamics in seabirds.”

Wandering Albatross, photograph by John Cooper

Reference:

Fay, R., Weimerskirch, H., Delord, K. & Barbraud, C. 2015.  Population density and climate shape early-life survival and recruitment in a long-lived pelagic seabird.  Journal of Animal Ecology DOI: 10.1111/1365-2656.12390.

John Cooper, ACAP Information Officer, 06 June 2015

The Kauai Endangered Seabird Recovery Project (KESRP) has commenced its annual monitoring by radar of nocturnal flights of Endangered Newell's Shearwaters or ‘A'o Puffinus newelli and Vulnerable Hawaiian Petrels or Ua'u Pterodroma sandwichensis at night on the Hawaiian island of Kauai. Two radar trucks are being used at 18 sites along Kaumualii and Kuhio Highways along with some county roads.  These sites have been chosen because they are areas where the seabirds are known to move between the sea and their montane breeding grounds.  The radar surveys are conducted at night during the first two hours after dark and two hours before dawn when the birds travel to and from their inland breeding sites (click here).

Radar truck on Kauai, photograph courtesy of the Kauai Endangered Seabird Recovery Project

“Radar is an important tool for tracking seabirds moving at night and is used around the world for this purpose”, said Dr. Andre Raine, KESRP project coordinator. “Because these two species of seabirds only fly back to their colonies at night it extremely hard to see and count them.  Radar allows us to ‘see' the birds flying overhead in the darkness as a series of dots passing across the radar screen. By assessing the speed of movement, the direction of travel, and the time that the event is recorded, we can then identify the birds to species.”

Radar has been used to study the movement of nocturnal seabirds on Kauai – and other islands—for many years. The first radar surveys were conducted on the island in 1993 and have continued at the same sites on a near annual basis.

“By surveying the same sites every year, we can see how our endangered seabirds are doing by looking at the change in the number of birds passing by the same sites each year,” Dr. Raine said. “Because Kauai holds 90 percent of the world's population   and a significant proportion of the world's population of Ua'u, understanding how the populations are changing at an island level is critical to their conservation.”

Radar observations will continue until September, with the peak of activity this month.

Newell's Shearwater, photograph by Eric Vanderwerf

Hawaiian Petrel, photograph courtesy of the Kauai Endangered Seabird Recovery Project

The KESRP is a Hawaiian Division of Forestry and Wildlife project, administered through the Pacific Studies Co-operative Unit of the University of Hawaiʻi at Manoa.  Formed in 2006, the project focuses primarily on the three procellariiform seabirds that breed on the island of Kauai: Newell’s Shearwater, Hawaiian Petrel and Band-rumped Storm Petrel Oceanodroma castro.

John Cooper, ACAP Information Officer, 05 June 2015