Airam Rodríguez (Department of Evolutionary Ecology, Estación Biológica de Doñana, Seville, Spain) and colleagues have published in the Journal of Ornithology on the effects of light pollution on fledging procellariiform species in the Balearic Islands.

The paper’s abstract follows:

“Petrels are among the most threatened group of birds.  On top of facing predation by introduced mammals and incidental bycatch, these seabirds have to deal with an emerging threat, light pollution, which is increasing globally.  Fledglings are disoriented and attracted to artificial lights in their maiden night flights from their nests to the sea.  Once grounded, they are exposed to multiple threats leading to high mortality.  We report on numbers of three petrel species (Balearic shearwater Puffinus mauretanicus, Scopoli’s shearwater Calonectris diomedea, and European storm-petrel Hydrobates pelagicus) rescued on the Balearic Islands, Mediterranean Sea, in the period 1999–2013. We assessed the proportion of grounded fledglings in the population and colonies impact based on radiance levels measured from a nocturnal satellite image. We also calculated the radius of light pollution impact. At least 304 fledgling birds were found stranded due to attraction to artificial lights, fatally affecting 8.5 % of them. The proportion of grounded fledglings ranged between 0.13 and 0.56 % of the fledglings produced annually. The body mass of Balearic and Scopoli’s shearwater fledglings decreased with rescue date. Light-induced mortality increased during the fledging period for Scopoli’s shearwaters. Birds were rescued at a mean distance of 4833 m from the nearest colony, and between 30 and 47 % of colonies were exposed to light-polluted areas. Although impact seems to be low for all species, urban development and, consequently, the increase in light pollution in the proximity of the colonies should be taken into account to reduce as much as possible this emerging source of mortality.”

Balearic Shearwater at sea, photograph by Beneharo Rodríguez

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

With thanks to Airam Rodríguez for information.

Reference:

Rodríguez, A., García, D., Rodríguez, B., Cardona, E., Parpal, L. & Pons, P. 2015.  Artificial lights and seabirds: is light pollution a threat for the threatened Balearic petrels?  Journal of Ornithology DOI 10.1007/s10336-015-1232-3.

John Cooper, ACAP Information Officer, 09 June 2015

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