1. Individual-based models (IBMs) are a powerful tool in predicting the consequences of environmental change on animal populations and supporting evidence-based decision making for conservation ...planning. 2. There are increasing proposals for wind farms in UK waters and seabirds are a vulnerable group, which may be at risk from these developments. 3. We developed a spatially explicit IBM to investigate the potential impacts of the installation of wind farms in the English Channel and North Sea on body mass, productivity and mortality of a breeding population of Northern gannets for which we have tracking data. 4. A baseline model with no wind farms accurately represented the status of a sample of tracked gannets at the end of the 90-day chick-rearing period, and the behaviourtime budget was similar to that of tracked gannets. 5. Model simulations in the presence of wind farms indicated that installations should have little impact on the gannet population, when either avoidance behaviour or collision risk scenarios were simulated. Furthermore, wind farms would need to be ten times larger or in more highly used areas in order to have population-level impacts on Alderney's gannets. 6. Synthesis and applications. Our spatially explicit individual-based models (IBM) high-light that it is vital to know the colony-specific foraging grounds of seabirds that may be impacted, when identifying potential wind farm sites, in order to account for cumulative impacts from multiple sites. Avoiding areas highly used for foraging and commuting, and avoiding large-scale developments should be effective in limiting gannet mortality as a result of collision, competition and energy expenditure. Our IBM provides a robust approach which can be adapted for other seabird populations or to predict the impacts from other types of spatial change in the marine environment.
Two separate approaches, a carcass sampling model and an exposure probability model, provided estimates of bird mortalities of 600 000 and 800 000, respectively, from the 2010 Deepwater Horizon MC ...252 oil spill in coastal waters of the Gulf of Mexico. Monte Carlo simulation of parameter uncertainty led to respective 95% uncertainty intervals of 320 000 to 1200 000 and 160 000 to 1900 000. Carcass sampling relied on expansion factors multiplied by counts of bird carcasses retrieved in shoreline surveys, whereas exposure probability estimated bird deaths as a product of estimated coastal bird density, average oil slick size, slick duration, and proportionate mortality due to oiling. The low proportion of small-sized carcasses recovered, compared with considerably higher proportions of small live birds in coastal Gulf habitats, indicate an especially low probability of recovery for small birds after oil spills at sea. Most mortality affected 4 species: laughing gull Leucophaeus atricilla (32% of the northern Gulf of Mexico population killed), royal tern Thalasseus maximus (15%), northern gannet Morus bassanus (8%) and brown pelican Pelecanus occidentalis (12%). Declines in laughing gulls were confirmed by ~60% reductions in National Audubon Society Christmas Bird Count data for 2010–2013 along the Gulf coast. Population-level effects in apex predators of this magnitude likely had effects on prey populations that warrant careful assessment.
The Northern Gannet (Morus bassanus) is a large marine bird whose whole North American population breeds in waters of eastern Canada. Opportunities to identify causes of morbidity and mortality in ...recently hatched birds of this species are therefore limited to this region of North America. During the three decades since 1990 of wildlife health surveillance at the Atlantic regional center of the Canadian Wildlife Health Cooperative, what appears to be a previously undescribed syndrome of ischemic leg necrosis affecting mainly hatch-year Northern Gannets has emerged, which may relate to some unique aspects of the life history of these birds. This syndrome, observed in 14 birds, is characterized by severe necrosis and fibrinopurulent inflammation of soft tissues of the feet extending along the whole tarsometatarsus. An infectious cause is proposed to explain the pattern of lesions observed in these birds, possibly favored by a specialized and rich vascular system in their legs and feet. An acute or subacute cardiomyopathy, thought to be secondary to the severe leg lesions, was also observed microscopically in six of these birds.
► Plastic entanglement causes mortality but the population-level consequences are unknown. ► At one colony, northern gannets used 18.46tonnes of plastic for nesting material. ► Synthetic rope appears ...to be preferentially selected. ► On average 65.63 birds are entangled annually. ► Current levels of mortality are unlikely to have population-level effects.
Entanglement with plastic debris is a major cause of mortality in marine taxa, but the population-level consequences are unknown. Some seabirds collect marine debris for nesting material, which may lead to entanglement. Here we investigate the use of plastics as nesting material by northern gannets Morus bassanus and assess the associated levels of mortality. On average gannet nests contained 469.91g (range 0–1293g) of plastic, equating to an estimated colony total of 18.46 tonnes (range 4.47–42.34tonnes). The majority of nesting material was synthetic rope, which appears to be used preferentially. On average 62.85±26.84 (range minima 33–109) birds were entangled each year, totalling 525 individuals over eight years, the majority of which were nestlings. Although mortality rates are high, they are unlikely to have population-level effects. The use of synthetic fibres as nesting material is a common strategy among seabirds, but the impacts of entanglement warrants further investigation.
Successful Marine Spatial Planning depends upon the identification of areas with high importance for particular species, ecosystems or processes. For seabirds, advancements in biologging devices have ...enabled us to identify these areas through the detailed study of at-sea behaviour. However, in many cases, only positional data are available and the presence of local biological productivity and hence seabird foraging behaviour is inferred from these data alone, under the untested assumption that foraging activity is more likely to occur in areas where seabirds spend more time. We fitted GPS devices and accelerometers to northern gannets Morus bassanus and categorised the behaviour of individuals outside the breeding colony as plunge diving, surface foraging, floating and flying. We then used the locations of foraging events to test the efficiency of 2 approaches: time-in-area and kernel density (KD) analyses, which are widely employed to detect highly-used areas and interpret foraging behaviour from positional data. For KD analyses, the smoothing parameter (h) was calculated using the ad hoc method (KDad hoc), and KDh=9.1, where h = 9.1 km, to designate core foraging areas from location data. A high proportion of foraging events occurred in core foraging areas designated using KDad hoc, KDh=9.1, and time-in-area. Our findings demonstrate that foraging activity occurs in areas where seabirds spend more time, and that both KD analysis and the time-in-area approach are equally efficient methods for this type of analysis. However, the time-in-area approach is advantageous in its simplicity, and in its ability to provide the shapes commonly used in planning. Therefore, the time-in-area approach can be used as a simple way of using seabirds to identify ecologically important locations from both tracking and survey data.
•Migration was tracked in European Northern gannets and Scopoli’s shearwaters.•Adults and juveniles use West-African coastal waters extensively in autumn/winter.•West-African waters are exposed to ...the highest level of uncontrolled fisheries.•Uncontrolled fisheries threaten seabirds via food competition and bycatch.•West African fisheries need better control, including bycatch mitigation.
Foreign fisheries massively harvest waters off West Africa, plundering local marine economies and threatening African food security. Here we warn that these fisheries might affect both juvenile and adult European seabirds during their autumn migration and at their wintering grounds. Using miniaturised GPS, satellite transmitters and geolocators, we tracked the migratory movements of 64 adult and juvenile Northern gannets (Morus bassanus) and Scopoli’s shearwaters (Calonectris diomedea) after their breeding season in the eastern Atlantic and the Mediterranean Sea, respectively. It was the first time ever that the movements of gannet fledglings were tracked with GPS accuracy. During winter (October to March) birds made extensive use of marine areas within the exclusive economic zones of Morocco, Western Sahara, Mauritania and Senegal. These juvenile and adult European seabirds are therefore dependent upon African marine resources and at risk from competition with fisheries, as well as intentional and incidental mortality by fishing gear. Those threats occur additionally to detrimental seabird–fishery interactions in Europe. There is an urgent need for improved marine conservation off West Africa, and our data demonstrating connectivity between specific European breeding colonies and African wintering areas are a major step towards stakeholder involvement.
Birds are the primary hosts of Chlamydia psittaci, a bacterium that can cause avian chlamydiosis in birds and psittacosis in humans. Wild seabirds are frequently admitted to wildlife rescue centers ...(WRC) at European Atlantic coasts, for example, in connection with oil spills. To investigate the extent of chlamydial shedding by these birds and the resulting risk for animals in care and the medical staff, seabirds from a French WRC were sampled from May 2011 to January 2014. By use of a quantitative PCR (qPCR), 195 seabirds belonging to 4 orders, 5 families and 13 species were examined, of which 18.5% proved to be Chlamydiaceae positive. The highest prevalence of shedders was found in northern gannets (Morus bassanus) (41%), followed by European herring gulls (Larus argentatus) (14%) and common murres (Uria aalge) (7%). Molecular characterization and phylogenetic analysis of qPCR-positive northern gannet samples revealed two variants of a strain closely related to C. psittaci. In European herring gulls and in one common murre, strains showing high sequence similarity to the atypical Chlamydiaceae-like C122 previously found in gulls were detected. Our study shows that seabirds from the northeastern Atlantic Ocean carry several chlamydial organisms, including C. psittaci-related strains. The staff in WRCs should take protective measures, particularly in the case of mass admissions of seabirds.
As we begin to manage our oceans in much more spatial detail we must understand a great deal more about oceanographic habitat preferences of marine mobile top predators. In this unique field study we ...test a hypothesis on the mechanisms defining mobile predator foraging habitat characteristics by comparing temporally and spatially detailed bio-physical oceanographic data from contrasting topographical locations. We contrast the foraging locations of two very different seabird species, gannets and storm petrels, by repeatedly sampling a bank and a nearby flat area over daily tidal cycles during spring and neap tides. The results suggest that storm petrels are linked to foraging in specific locations where internal waves are produced, which is mainly on banks. These locations can also include the presence of high biomass of chlorophyll. In contrast, the location where more gannets are foraging is significantly influenced by temporal variables with higher densities of foraging birds much more likely during the neap tide than times of spring tide. The foraging times of both species was influenced by differences between the vertical layers of the water column above and below the thermocline; via either vertical shear of horizontal currents or absolute differences in speed between layers. Higher densities of foraging gannets were significantly more likely to be found at ebb tides in both bank and flat regions however over the bank, the density of foraging gannets was higher when the differences in speed between the layers were at a maximum. Both gannets and storm petrels appear to be more likely to forage when wind direction is opposed to tidal direction. This detailed understanding links foraging behaviour to predictable spatial and temporal bio-physical vertical characteristics and thus can be immediately used to explain variance and increase certainty in past abundance and distributional surveys. These results also illuminate the types of variables that should be considered when assessing potential changes to the distribution and characteristics of habitats from increased anthropogenic disturbances such as large scale offshore wind, wave and tidal renewable deployments.
Offshore wind farms are rapidly being permitted along the Atlantic Coast of the United States. Exposure of northern gannet (Morus bassanus) to multiple wind farms could affect the population because ...gannets are vulnerable to both displacement and collision. A critical question is whether wind-farm siting decisions can reduce cumulative exposure of gannets. We quantified how 3 different wind-farm siting scenarios would cumulatively expose gannets. Two independent gannet abundance data sets were used to ensure robustness of the analysis: 1) individual tracking data from birds captured in the mid-Atlantic region of the United States from 2012–2015 and 2) relative abundance models developed by the National Oceanic and Atmospheric Administration from surveys conducted from 1978–2014 along the Atlantic Coast of the United States. Our results indicate that for initial development, projects sited close to shore and in shallow areas exposed gannets at the greatest rates; however, no siting scenario effectively avoided exposing gannets because of the birds’ broad distribution across the outer continental shelf. These findings suggest that gannets will be cumulatively exposed regardless of siting scenario and management actions should focus on efforts to minimize adverse effects at each wind farm rather than avoiding exposure through siting decisions.
PDF
