Olfactory cues have been shown to be important to homing petrels at night, but apparently those procellariiform species that also come back to the colony during the day are not impaired by smell deprivation. However, the nycthemeral distribution of homing, i.e. whether displaced birds released at night return to their burrow by night or during daylight, has never been investigated. To explore this question, we studied the homing behaviour of Cory’s shearwater (Calonectris borealis) in the only known population where these birds are active at the colony both during the day and the night. Here, we compared the nocturnal versus diurnal homing schedule of birds treated with zinc sulphate to induce a reversible but complete anosmia, to that of controls. Our results show that anosmic shearwaters were unable to home in the dark and were constrained to wait for the daylight to find their burrow again. Our results confirm that olfaction is the basic sensory input for homing by night even in a petrel species that is diurnally active at the colony.
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.
- Conservation biology : the journal of the Society for Conservation Biology
- Published about 3 years ago
Artificial lights at night cause high mortality of seabirds, one of the most endangered groups of birds globally. Fledglings of burrow-nesting seabirds, and to a lesser extent adults, are grounded by lights when they fly at night. We review the current state of knowledge of light attraction, identify information gaps and propose measures to address the problem. Although other avian families such as Alcidae and Anatidae can be involved, the most affected seabirds are petrels and shearwaters: at least 56 species, more than one-third of them (24) threatened, are grounded by lights. Grounded seabirds have been found worldwide, mainly on oceanic islands but also at some continental locations. Petrel breeding grounds confined to formerly uninhabited islands are particularly at risk from ever-growing levels of light pollution due to tourism and urban sprawl. Where it is impractical to ban external lights, rescue programs of grounded birds offer the most immediate and extended mitigation measures to reduce light-induced mortality, saving thousands of birds every year. These programs also provide useful information for seabird management. However, the data typically are fragmentary and often strongly biased so the phenomenon is poorly understood, leading to inaccurate impact estimates. We identified as the most urgent priority actions: 1) estimation of mortality and impact on populations; 2) assessment of threshold light levels and safe distances from light sources; 3) documenting the fate of rescued birds; 4) improvement of rescue campaigns, particularly in terms of increasing recovery rates and level of care; and 5) research on seabird-friendly lights to reduce attraction. More research is necessary to improve our understanding of this human-wildlife conflict and to design effective management and mitigation measures. This article is protected by copyright. All rights reserved.
The northern fulmar (Fulmarus glacialis) is defined as an indicator species of plastic pollution by the Oslo-Paris Convention (OSPAR) for the North-East Atlantic, but few data exist for fulmars from Norway. Moreover, the relationship between uptake of plastic and pollutants in seabirds is poorly understood. We analysed samples of fulmars from Norwegian waters and compared the POP concentrations in their liver and muscle tissue with the corresponding concentrations in the loads of ingested plastic in their stomachs, grouped as ‘no’, ‘medium’ (0.01 - 0.21 g; 1 - 14 pieces of plastic) or ‘high’ (0.11 - 0.59 g; 15 - 106 pieces of plastic). POP concentrations in the plastic did not differ significantly between the high and medium plastic ingestion group for sumPCBs, sumDDTs and sumPBDEs. By combining correlations among POP concentrations, differences in tissue concentrations of POPs between plastic ingestion subgroups, fugacity calculations and bioaccumulation modeling, we showed that plastic is more likely to act as a passive sampler than as a vector of POPs, thus reflecting the POP profiles of simultaneously ingested prey.
According to niche theory, mechanisms exist that allow co-existence of organisms that would otherwise compete for the same prey and other resources. How seabirds cope with potential competition during the non-breeding period is poorly documented, particularly for small species. Here we investigate for the first time the potential role of spatial, environmental (habitat) and trophic (isotopic) segregation as niche-partitioning mechanisms during the non-breeding season for four species of highly abundant, zooplanktivorous seabird that breed sympatrically in the Southern Ocean. Spatial segregation was found to be the main partitioning mechanism; even for the two sibling species of diving petrel, which spent the non-breeding period in overlapping areas, there was evidence from distribution and stable isotope ratios for differences in habitat use and diving depth.
Plastic is now one among one of the most pervasive pollutants on the planet, and ocean circulation models predict that the Arctic will become another accumulation zone. As solutions to address marine plastic emerge, is essential that baselines are available to monitor progress towards targets. The northern fulmar (Fulmarus glacialis), a widely-distributed seabird species, has been used as a biological monitor for plastic pollution in the North Sea, and could be a useful monitoring species elsewhere. We quantified plastic ingested by northern fulmars from the southeastern Canadian waters of the Labrador Sea with the objective of establishing a standardized baseline for future comparisons. Over two years we sampled 70 fulmars and found that 79% had ingested plastic, with an average of 11.6 pieces or 0.151g per bird. Overall, 34% of all fulmars exceeded the Ecological Quality Objective for marine litter, having ingested >0.1g of plastic.
Commercial fisheries may impact marine ecosystems and affect populations of predators like seabirds. In the Southern Ocean, there is an extensive fishery for Antarctic krill Euphausia superba that is projected to increase further. Comparing distribution and prey selection of fishing operations versus predators is needed to predict fishery-related impacts on krill-dependent predators. In this context, it is important to consider not only predators breeding near the fishing grounds but also the ones breeding far away and that disperse during the non-breeding season where they may interact with fisheries. In this study, we first quantified the overlap between the distribution of the Antarctic krill fisheries and the distribution of a krill dependent seabird, the Antarctic petrel Thalassoica antarctica, during both the breeding and non-breeding season. We tracked birds from the world biggest Antarctic petrel colony (Svarthamaren, Dronning Maud Land), located >1000 km from the main fishing areas, during three consecutive seasons. The overall spatial overlap between krill fisheries and Antarctic petrels was limited but varied greatly among and within years, and was high in some periods during the non-breeding season. In a second step, we described the length frequency distribution of Antarctic krill consumed by Antarctic petrels, and compared this with results from fisheries, as well as from diet studies in other krill predators. Krill taken by Antarctic petrels did not differ in size from that taken by trawls or from krill taken by most Antarctic krill predators. Selectivity for specific Antarctic krill stages seems generally low in Antarctic predators. Overall, our results show that competition between Antarctic petrels and krill fisheries is currently likely negligible. However, if krill fisheries are to increase in the future, competition with the Antarctic petrel may occur, even with birds breeding thousands of kilometers away.
Marine plastic litter has become a major threat to wildlife. Marine animals are highly susceptible to entanglement and ingestion of debris at sea. Governments all around the world are being urged to monitor litter sources and inputs, and to mitigate the impacts of marine litter, which is primarily composed of plastics. European policies, such as Oslo-Paris Convention (OSPAR) and Marine Strategy Framework Directive (MSFD) have adopted the monitoring of a seabird species, the Northern Fulmar (Fulmarus glacialis), as an environmental quality indicator through the analysis of stomach contents of beached Fulmar specimens. The aims of this research were to: firstly set a baseline investigation of multispecies of seabirds in Ireland affected by the ingestion of litter and, secondly to investigate the feasibility of using Fulmar and/or other potential species of seabird as an indicator for marine debris in Ireland through beached bird surveys. Within 30 months, 121 birds comprising 16 different species were collected and examined for the presence of litter. Of these, 27.3% (n = 33) comprising 12 different species were found to ingest litter, mainly plastics. The average mass of ingested litter was 0.141 g. Among 14 sampled Northern Fulmars, 13 (93%) had ingested plastic litter, all of them over the 0.1 g threshold used in OSPAR and MSFD policy target definitions. Results show that seabirds in Ireland are ingesting marine litter, as in many other countries in the world. Monitoring seabird litter ingestion has the potential to form part of a wider marine litter monitoring programme that can help to inform mitigation and management measures for marine litter.
Marine plastic pollution affects seabirds, including Pacific Northern Fulmars (Fulmarus glacialis rodgersii), that feed at the surface and mistake plastic for prey or incidentally ingest it. Direct and indirect health issues can result, including satiety and possibly leading to inefficient foraging. Our objective was to examine fulmar body condition, identify cephalopod diet to species, enumerate and weigh ingested plastic, and determine if prey number and size were correlated with ingested plastics in beach-cast fulmars wintering in Monterey Bay California (2003, n=178: 2007, n=185). Fulmars consumed mostly Gonatus pyros, G. onyx, and G. californiensis of similar size for both years. We found a significant negative correlation between pectoral muscle index and average size of cephalopod beaks per stomach; a significant increase in plastic categories between 2003 and 2007; and no significant correlation between number and mass of plastic compared with number and size of prey for either year.
Marine birds have been found to ingest plastic debris in many of the world’s oceans. Plastic accumulation data from necropsies findings and regurgitation studies are presented on 13 species of marine birds in the North Atlantic, from Georgia, USA to Nunavut, Canada and east to southwest Greenland and the Norwegian Sea. Of the species examined, the two surface plungers (great shearwaters Puffinus gravis; northern fulmars Fulmarus glacialis) had the highest prevalence of ingested plastic (71% and 51%, respectively). Great shearwaters also had the most pieces of plastics in their stomachs, with some individuals containing as many of 36 items. Seven species contained no evidence of plastic debris. Reporting of baseline data as done here is needed to ensure that data are available for marine birds over time and space scales in which we see changes in historical debris patterns in marine environments (i.e. decades) and among oceanographic regions.