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Satellite telemetry and digital aerial surveys show strong displacement of red-throated divers (Gavia stellata) from offshore wind farms

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Abstract

Expansion of offshore wind energy is vital for the reduction of CO2 emissions. However, offshore wind farms may negatively impact the environment without proper planning. Here we assess the robustness of the conclusions of earlier studies that the strictly protected red-throated diver, Gavia stellata, is strongly displaced from wind farms in the German Bight (North Sea). We modelled the distribution of divers based on two independent data sets, digital aerial surveys and satellite telemetry, in relation to the dynamic offshore environment and anthropogenic pressures. Both data types found that divers were strongly displaced from wind farms in suitable habitat. The displacement effect gradually decreased with distance from the wind farms (being very strong up to 5 km away), but a significant effect could be detected up to 10–15 km away. The telemetry data further indicated that the displacement distance decreased with decreasing visibility. The displacement distance was also shorter during the day than during the night, potentially as a response to aviation and navigation lights of the wind farms. These findings should be taken into consideration in marine spatial planning to avoid cumulative impacts on red-throated diver populations.

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... Divers show avoidance behavior toward vessels at distances of more than one kilometer (Bellebaum et al., 2006;Fliessbach et al., 2019) and show reduced densities in areas of high ship traffic (Schwemmer et al., 2011;Burger et al., 2019). Many studies have been conducted into reactions of divers to offshore wind farms, consistently reporting avoidance behavior toward the wind farm itself and lower sighting rates within a certain buffer zone around the wind farm (Dierschke et al., 2016;Mendel et al., 2019;Allen et al., 2020;Heinänen et al., 2020). ...
... The mean spring population for the German North Sea was estimated by the present study at 16,330 divers (95% CI: 15,912) during 2013-2018 when most of the wind farms were built, and 15,942 divers (95% CI: 14,836-17,176) during 2002built, and 15,942 divers (95% CI: 14,836-17,176) during -2012built, and 15,942 divers (95% CI: 14,836-17,176) during (excluding the years 2006built, and 15,942 divers (95% CI: 14,836-17,176) during and 2007 with few or no wind farms built. Our estimates for the early years are thus in the range of the study by Garthe et al. (2015), even if numbers from single surveys show that diver abundance fluctuates strongly during spring (Heinänen et al., 2020) and thus, some variability in the population estimates can be expected from different sets of surveys. ...
... Seabird species vary strongly in their sensitivity to OWFs (Furness et al., 2013). For divers, strong avoidance behavior to OWFs has been found in all recent studies (Mendel et al., 2019;Allen et al., 2020;Heinänen et al., 2020). ...
Article
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The utilization of marine renewable energies such as offshore wind farming leads to globally expanding human activities in marine habitats. While knowledge on the responses to offshore wind farms and associated shipping traffic is accumulating now at a fast pace, it becomes important to assess the population impacts on species affected by those activities. In the North Sea, the protected diver species Red-throated Diver (Gavia stellata) and Black-throated Diver (Gavia arctica) widely avoid offshore wind farms. We used an explicit spatio-temporal Bayesian model to get a robust estimate of the diver population during the spring season between 2001 and 2018, based on a set of aerial surveys from long-term monitoring programs within the German North Sea. Despite the erection of 20 offshore wind farms in the study area and marked responses of divers to wind farms, model results indicated that there was no population decline, and overall numbers fluctuated around 16,600 individuals, with average annual 95% CI ranging between 13,400 and 21,360 individuals. Although, avoidance behavior due to wind farm development led to a more narrowly focused spatial distribution of the birds centered in the persistent high concentration zone in the Eastern German Bight Special Protection Area, the results provide no indication of negative fitness consequences on these long-lived species. However, more research is needed on habitat use and food availability in this regard.
... In this study, we analysed the migratory behaviour of a seabird species, the red-throated diver (Gavia stellata), that is increasingly influenced by human activities in one of their most important winter and spring staging areas in Europe, the German Bight (eastern North Sea) (Garthe et al. 2007(Garthe et al. , 2015Dierschke et al. 2012;Burger et al. 2019;Mendel et al. 2019;Heinänen et al. 2020). In this winter population, strong avoidance of offshore wind farm areas was observed (Mendel et al. 2019;Heinänen et al. 2020;Vilela et al. 2021) but, so far, no decline in wintering population numbers of this long-lived species (Vilela et al. 2021). ...
... In this study, we analysed the migratory behaviour of a seabird species, the red-throated diver (Gavia stellata), that is increasingly influenced by human activities in one of their most important winter and spring staging areas in Europe, the German Bight (eastern North Sea) (Garthe et al. 2007(Garthe et al. , 2015Dierschke et al. 2012;Burger et al. 2019;Mendel et al. 2019;Heinänen et al. 2020). In this winter population, strong avoidance of offshore wind farm areas was observed (Mendel et al. 2019;Heinänen et al. 2020;Vilela et al. 2021) but, so far, no decline in wintering population numbers of this long-lived species (Vilela et al. 2021). Red-throated divers are listed in Annex II of the Bern Convention, Annex I of the EU Birds Directive and as critically endangered on the HELCOM (Helsinki Commission) convention (BirdLife International 2022). ...
... We captured divers using the night-lighting technique (Whitworth et al. 1997;Ronconi et al. 2010). For a detailed description of tagging, see Burger et al. (2019), Kleinschmidt et al. (2019), Heinänen et al. (2020) and www. diver track ing. ...
Article
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In this study, the annual movements of a seabird species, the red-throated diver (Gavia stellata), were investigated in space and time. Between 2015 and 2017, 33 individuals were fitted with satellite transmitters at the German Bight (eastern North Sea). In addition, stable isotope analyses of feathers (δ13C) were used to identify staging areas during the previous moult. The German Bight is an important area for this species, but is also strongly affected by anthropogenic impacts. To understand how this might affect populations, we aimed to determine the degree of connectivity and site fidelity, and the extent to which seasonal migrations vary among different breeding locations in the high Arctic. Tagged individuals migrated to Greenland (n = 2), Svalbard (n = 2), Norway (n = 4) and northern Russia (n = 25). Although individuals from a shared breeding region (northern Russia) largely moved along the same route, individuals dispersed to different, separate areas during the non-breeding phase. Kernel density estimates also overlapped only partially, indicating low connectivity. The timing of breeding was correlated with the breeding longitude, with 40 days later arrival at the easternmost than westernmost breeding sites. Repeatability analyses between years revealed a generally high individual site fidelity with respect to spring staging, breeding and moulting sites. In summary, low connectivity and the distribution to different sites suggests some resilience to population decline among subpopulations. However, it should be noted that the majority of individuals breeding in northern Russia migrated along a similar route and that disturbance in areas visited along this route could have a greater impact on this population. In turn, individual site fidelity could indicate low adaptability to environmental changes and could lead to potential carry-over effects. Annual migration data indicate that conservation planning must consider all sites used by such mobile species.
... Red-throated divers (RTDs; Gavia stellata) are a northerly distributed species of aquatic bird, generally occupying latitudes above 50°N (Carboneras et al. 2020). This species faces many of the threats previously mentioned (Schmutz et al. 2009 and is known to be vulnerable to anthropogenic presence (Schwemmer et al. 2011, Nummi et al. 2013, Uher-Koch et al. 2015 and structures (Furness et al. 2013, Mendel et al. 2019, Heinänen et al. 2020. This aversion to anthropogenic presence could be detrimental to demographic rates, through displacement effects (Drewitt and Langston 2006), but these effects are hard to observe and measure directly, as the birds are often in inaccessible locations. ...
... The limited information available on RTD foraging allowed us to generate broad predictions on how foraging behaviour could differ between regions. Surveys of non-breeding season distribution show RTDs tend to favour habitats with water depths less than 20 m (Petersen et al. 2010, O'Brien et al. 2012, but can also be found in deeper waters (Heinänen et al. 2020). Biologging data from a single RTD in the breeding season provided some evidence to support this shallow depth usage, with the individual showing few dives reaching depths deeper than 20 m (Duckworth et al. 2020b). ...
Article
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Differing environmental conditions can have profound effects on many behaviours in animals, especially where species have large geographic ranges. Seasonal changes or progression through life history stages impose differential constraints, leading to changes in behaviours. Furthermore, species which show flexibility in behaviours, may have a higher capacity to adapt to anthropogenic‐induced changes to their environment. The red‐throated diver (RTD) is an aquatic bird, that is able to forage in both freshwater and marine environments, though little else is known about its behaviours and its capacity to adapt to different environmental conditions. Here, we use time‐depth recorders and saltwater immersion loggers to examine the foraging behaviour of RTDs from three regions across northwest Europe. We found that in the breeding season, birds from two regions (Iceland and Scotland) foraged in the marine environment, while birds from Finland, foraged predominantly in freshwater. Most of the differences in diving characteristics were at least partly explained by differences in foraging habitat. Additionally, while time spent foraging did not change through the breeding season, dives generally became more pelagic and less benthic over the season, suggesting RTDs either switched prey or followed vertical prey movements, rather than increasing foraging effort. There was a preference for foraging in daylight over crepuscular hours, with a stronger effect at two of the three sites. Overall, we provide the first investigation of RTD foraging and diving behaviour from multiple geographic regions and demonstrate variation in foraging strategies in this generalist aquatic predator, most likely due to differences in their local environment.
... For some species of bird, many of the detrimental effects from windfarm developments likely occur specifically during the molt and winter period (Dierschke et al., 2017;Heinänen et al., 2020). Some diving birds, including divers (or "loons"; Gavia spp), undergo a synchronous molt of their flight feathers, rendering them flightless for a few weeks (HiDEF, 2016;Kjellén, 1994). ...
... Therefore, linking the molting and winter distributions to the associated breeding population is essential in quantifying the potentially deleterious effects of offshore wind farm interactions on demographic rates, such as survival or breeding success. Red-throated divers (RTDs; Gavia stellata) are one such species and have recently been the focus of much interest due to their avoidance of offshore windfarms and associated activity (Furness et al., 2013;Heinänen et al., 2020). One of the most pressing knowledge gaps currently is understanding the molting and winter distributions used by different breeding populations. ...
Article
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Migratory species have geographically separate distributions during their annual cycle, and these areas can vary between populations and individuals. This can lead to differential stress levels being experienced across a species range. Gathering information on the areas used during the annual cycle of red‐throated divers (RTDs; Gavia stellata) has become an increasingly pressing issue, as they are a species of concern when considering the effects of disturbance from offshore wind farms and the associated ship traffic. Here, we use light‐based geolocator tags, deployed during the summer breeding season, to determine the non‐breeding winter location of RTDs from breeding locations in Scotland, Finland, and Iceland. We also use δ15N and δ13C isotope signatures, from feather samples, to link population‐level differences in areas used in the molt period to population‐level differences in isotope signatures. We found from geolocator data that RTDs from the three different breeding locations did not overlap in their winter distributions. Differences in isotope signatures suggested this spatial separation was also evident in the molting period, when geolocation data were unavailable. We also found that of the three populations, RTDs breeding in Iceland moved the shortest distance from their breeding grounds to their wintering grounds. In contrast, RTDs breeding in Finland moved the furthest, with a westward migration from the Baltic into the southern North Sea. Overall, these results suggest that RTDs breeding in Finland are likely to encounter anthropogenic activity during the winter period, where they currently overlap with areas of future planned developments. Icelandic and Scottish birds are less likely to be affected, due to less ship activity and few or no offshore wind farms in their wintering distributions. We also demonstrate that separating the three populations isotopically is possible and suggest further work to allocate breeding individuals to wintering areas based solely on feather samples. Understanding the distributions of species vulnerable to disturbance from anthropogenic activity is vital in assessing future consequences. Using remote sensing technology, we tracked the movements of red‐throated divers from three breeding locations to identify their overwinter distributions. We then linked these population level differences in distribution to differences in isotopic signatures of feathers grown during the moulting period.
... We took blood samples from 45 red-throated divers captured between 54 • N 7 • E and 55 • N 8 • E in an internationally important non-breeding habitat, the eastern German Bight (North Sea) in winter and spring within the framework of the DIVER project [31,[38][39][40][41][42] N) of single individuals was available to be linked with haemosporidian parasite infection. The overall objective of the study presented here is to document the infestation of haemosporidian parasites in European red-throated divers. ...
... Bird capture and sampling were carried out in accordance with the local legislation. Sampling was conducted in the eastern German Bight (North Sea Germany) about 20 to 30 km west of the island of Amrum in three consecutive years: March to April 2015, February to March 2016 and March 2017 [31,[38][39][40][41][42]. A total of 45 red throated divers were captured to be tagged with satellite transmitters within the study area. ...
Article
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Haemosporida, vector-transmitted blood parasites, can have various effects and may also exert selection pressures on their hosts. In this study we analyse the presence of Haemosporida in a previously unstudied migratory seabird species, the red-throated diver Gavia stellata. Red-throated divers were sampled during winter and spring in the eastern German Bight (North Sea). We used molecular methods and data from a related tracking study to reveal (i) if red-throated divers are infected with Haemosporida of the genera Leucocytozoon, Plasmodium and Haemoproteus, and (ii) how infection and prevalence are linked with the breeding regions of infected individuals. Divers in this study were assigned to western Palearctic breeding grounds, namely Greenland, Svalbard, Norway and Arctic Russia. We found a prevalence of Leucocytozoon of 11.0% in all birds sampled (n = 45), of 33.0% in birds breeding in Norway (n = 3) and of 8.3% in birds breeding in Arctic Russia (n = 25). For two birds that were infected no breeding regions could be assigned. We identified two previously unknown lineages, one each of Plasmodium and Leucocytozoon. Haemosporida have not been detected in birds from Greenland (n = 2) and Svalbard (n = 2). In summary, this study presents the first record of Haemosporida in red-throated divers and reports a new lineage of each, Plasmodium and Leucocytozoon GAVSTE01 and GAVSTE02, respectively.
... In the non-breeding season, marine birds can be more far ranging, which complicates apportioning. Satellite or GPS tracking may be used for some marine bird species over long enough timescales to cover both breeding and non-breeding periods (Buckingham et al., 2022;Duckworth et al., 2022;Heinänen et al., 2020). However, for many species of concern, such tags are not available due to geographical, size or weight restrictions. ...
Article
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Offshore wind energy development (OWED) is rapidly expanding globally and has the potential to contribute significantly to renewable energy portfolios. However, development of infrastructure in the marine environment presents risks to wildlife. Marine birds in particular have life history traits that amplify population impacts from displacement and collision with offshore wind infrastructure. Here, we present a broadly applicable framework to assess and mitigate the impacts of OWED on marine birds. We outline existing techniques to quantify impact via monitoring and modeling (e.g., collision risk models, population viability analysis), and present a robust mitigation framework to avoid, minimize, or compensate for OWED impacts. Our framework addresses impacts within the context of multiple stressors across multiple wind energy developments. We also present technological and methodological approaches that can improve impact estimation and mitigation. We highlight compensatory mitigation as a tool that can be incorporated into regulatory frameworks to mitigate impacts that cannot be avoided or minimized via siting decisions or alterations to OWED infrastructure or operation. Our framework is 2 intended as a globally-relevant approach for assessing and mitigating OWED impacts on marine birds that may be adapted to existing regulatory frameworks in regions with existing or planned OWED.
... The BACI approach however allowed us to assess the OWF effects based on relative density changes. All seabird surveys were conducted during daytime, thus possible different reactions towards OWFs at night, which were documented in the study area for red-throated divers (Gavia stellata) (Heinänen et al., 2020), were not investigated as part of this study. We did not account for uncertainty in species identification which can be substantially different between digital and visual survey methods (Johnston et al., 2015). ...
Article
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The increasing development of offshore wind farms (OWFs) worldwide leads to possible conflicts with the ecological requirements of top predators that largely depend on offshore areas. Seabird species exhibit different behavioural reactions to OWFs, ranging from avoidance resulting in habitat loss, to attraction causing an increased risk of colliding with the turbines. We investigated how OWFs affected the densities and distributions of guillemots and kittiwakes breeding in the southern North Sea and if the effects varied among seasons using a 'before-after control impact' (BACI) analysis approach based on a large-scale and long-term dataset covering 14 years before and 3 years after the construction of OWFs. Guillemot relative density in the OWF decreased by 63% in spring, and by 44% in the breeding season. Kittiwake relative density in the OWF decreased by 45% in the breeding season, and not significantly by 10% in spring. We furthermore estimated the response radii to the OWF for both species and seasons, finding that guillemots showed a response radius of ~9 km in spring and kittiwakes a radius of ~20 km in the breeding season. The results underline the value of large-scale and long-term assessments considering seasonal variation throughout the yearly cycle. The here provided information on the seasonally different reactions of seabirds to OWFs adds substantially to our current knowledge and provides the necessary basis for reliable estimations of OWF effects on guillemots and kittiwakes. Such evaluations are urgently needed for future planning and management recommendations to decision-makers.
... Whilst renewable energy is a vital contributor in mitigating the effects of climate change by reducing global carbon emissions, the impacts of large-scale deployment of offshore wind on marine wildlife remains unclear (Masden et al. 2015). Red-throated divers are sensitive to disturbance caused by offshore wind farms, which leads to displacement from their foraging areas (Furness et al. 2013;Halley & Hopshaug 2007;Heinänen et al. 2020;Mendel et al. 2019;Percival 2014;Petersen et al. 2006;Welcker & Nehls 2016). However, the energetic costs and demands of this displacement on both individuals and populations are unknown. ...
Technical Report
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This report details the third field season of the Red-throated Diver Energetics Project (https://jncc.gov.uk/our-work/rtde-project/). During 2018-2020, archival geolocator (GLS) and time depth recorder (TDR) tags were deployed and retrieved from red-throated divers breeding in Scotland, Finland and Iceland to quantify foraging behaviour and approximate non-breeding season locations. This empirical data will provide insight into the time divers spend foraging, thus providing insight into whether divers potentially have capacity to accommodate displacement effects of offshore wind development. Full report can be found here: https://hub.jncc.gov.uk/assets/fef1c3be-d501-4beb-a62a-6e4382614170
... Door uitschieters is deze trend echter onzeker. Het beeld bestaat dat Roodkeelduikers windparken op zee mijden (zie bijvoorbeeldHeinänen et al. 2020), maar het is vooralsnog onduidelijk wat voor effect dat heeft op de populatie.Figuur 6.30. Slobeend. ...
Technical Report
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In the Netherlands, large-scale and systematic waterbird surveys have been carried out for decades. This longstanding tradition is part of the national governmental ecological surveillance scheme (‘Netwerk Ecologische Monitoring’), has a fixed set up (described in Tables 2.1-2.3 and Figure 2.1) and is carried out according to standardised guidelines. Sovon coordinates this scheme in close collaboration with national as well as regional governmental bodies and Statistics Netherlands (trend analyses and quality control). The data is mainly used to inform about species abundance and their trends. These are estimated at a national scale as well as for specific sites (Natura 2000) or specific evaluations (agri-environmental schemes in rural areas). Additionally, the data is used in several international frameworks, such as the International Waterbird Census (IWC), goose surveys of Wetlands International/European Goose Management Platform, the Trilateral Monitoring and Assessment Program (TMAP) of the Wadden Sea countries and the biodiversity indicators for the Marine Strategy Framework Directive/OSPAR. After decades of continuous increase, the average number of waterbirds in the Netherlands stabilised already around 2000 and is declining in recent years. The decline is mainly due to lower numbers in some goose and swan species (Figure 6.1). Species that primarily overwintered southwest of the Netherlands are now showing an increase in the Netherlands because of a range shift caused by milder winters (Figure 4.3), while the group of species that mostly overwinter northeast of our country have been declining here over the past decades. Trends vary among the different foraging types. Grass-eaters are declining (mostly due to the decrease in some geese and swan species), while fish-eaters are stabilising after an increase. When comparing groups living in different habitats, seabirds are declining the most. Many species qualifying for Natura 2000-sites show a status quo of their long-term trends. Abundance in species subject to a favourable conservation status usually is still above levels which previously had been used for target-setting (17 out of 26 species, Figure 4.5). On the other hand, a group of 20 species for which an unfavourable conservation status was assessed did not show signs of recovery partly because of developments at flyway level. At site-level there are 27 SPAs for which at least half of the qualifying species occur in numbers above conservation objectives (Figure 4.6), while in 30 SPAs numbers in at least half of all qualifying species remained below target level.
... Whilst renewable energy is a vital contributor in mitigating the effects of climate change by reducing global carbon emissions, the impacts of large-scale deployment of offshore wind on marine wildlife remains unclear (Masden et al. 2015). Red-throated divers (Gavia stellata) are sensitive to disturbance caused by offshore wind farms, which leads to displacement from their foraging areas (Furness et al. 2013;Halley & Hopshaug 2007;Heinänen et al. 2020;Mendel et al. 2019;Percival 2014;Petersen et al. 2006;Welcker & Nehls 2016). However, the energetic costs and demands of this displacement on both individuals and populations are unknown. ...
Technical Report
Full-text available
Offshore wind development around Europe is increasing to meet the demands for renewable energy production to help meet climate change targets. It is known that marine birds such as red-throated divers (Gavia stellata) are highly sensitive to disturbance caused by the construction and operation of offshore wind farms and are subsequently displaced from areas used in the non-breeding season. But the physiological, energetic and demographic consequences of such effective habitat loss is currently unknown. This report details the fourth and final field season of the Red-throated Diver Energetics Project (https://jncc.gov.uk/our-work/rtde-project/). During 2018-2021, archival geolocator (GLS) and time depth recorder (TDR) tags were deployed and retrieved from red-throated divers breeding in Scotland, Finland and Iceland to quantify foraging behaviour and approximate non-breeding season locations. This empirical data will provide insight into the time divers spend foraging, thus providing insight into whether divers potentially have the capacity to accommodate displacement effects of offshore wind development.
... These effects may be direct or indirect: (a) wind farms may negatively impact bats and birds through collision with wind-energy structures [13,14], with mortality mostly affecting soaring and migratory birds [15,16]; and (b) wind farms may influence birds indirectly by presenting movement barriers, vibration disturbance, high noise, and electromagnetic radiation [17,18]. Wind farms can thus have impacts in terms of displacement, movement-pattern changes, and effects on breeding success [19,20], which may eventually result in declines in species number and abundance at both global and national scales [21][22][23][24]. Balancing the development of wind energy facilities and bird conservation, and mitigating these negative effects have become significant issues for biodiversity and conservation worldwide. ...
Article
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Abstract Although wind power is a promising source of renewable energy, previous studies have focused on uncovering species and abundance decreases caused by wind farms. However, very few studies focus on collision risk of onshore wind farms in relation to birds’ movements which are the important indicators for balancing wind energy development and biodiversity conservation. Here, birds’ movement were recorded by combining 15 ducks’ satellite tracking and six field surveys to assess collision risks in Yangtze River Mouth, the wintering site for migratory waterbirds along the East Asian–Australasian Flyway. It is found that distances between ducks’ locations and nearest wind turbines in middle and later wintering periods were significantly higher than during early period. Besides, ducks inside wind farm tended to fly outside turbine rotor height range (45–135 m: between lowest and highest points the rotor tips) within 300 m from the dyke where the turbines were located, thus decreasing their collision risk. Ducks also tended to fly below the minimum rotor tip height (
... The results of our exemplary application of the novel approach supported the results of previous studies of the reactions of marine birds to human activities. Red-throated loons and common murres were previously shown to avoid the footprints of OWFs (Dierschke et al., 2016;Heinaenen et al., 2020;. Although the results for common murres were not significant in the current study, for this species, the second strongest OWF avoidance was measured, and the pvalue of p = 0.11 nevertheless strongly suggests an existing influence. ...
Article
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We present an integrative statistical approach for estimating the current conditions of marine-bird habitats affected by human activities. We first estimated the influence of multiple human offshore activities on the species of interest using integrative regression techniques. We then used these models to predict the distribution and abundance of the species throughout the study area, in both the current situation, with human activities, and in a hypothetical situation without the effects of the studied human activities. We finally developed different measures related to the comparison between these two scenarios. The presented approach allows the integration of bird-count data from different sources and sampling schemes, thus maximizing the underlying database. It also provides a local metric highlighting critical regions where locally high abundance is co-localized with large declines in abundance due to human activities, as well as a global metric quantifying the overall condition of the marine-bird habitat in the study area in relation to human disturbance. This approach allows us to assess the cumulative influence of several anthropogenic pressures. We exemplarily applied the above approach to four different species and two different sea regions, namely European herring gulls and long-tailed ducks in the German section of the Baltic Sea, and European herring gulls, red-throated loons, and common murres in the German–Dutch–Belgian part of the North Sea. The considered activities were offshore wind farms, bottom-trawling fishery, and ship traffic. The results confirmed the avoidance of and attraction to human activities by marine bird species found in previous studies. These results show that the methods developed here can be used to provide indicators for inclusion in bird assessments under OSPAR and HELCOM conventions, and MSFD Article 8, criterion D1C5 (habitat for the species). The resulting indicator can be used to inform programmes of measures under MSFD Article 13.
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Aim The United States Atlantic Outer Continental Shelf (OCS) has considerable offshore wind energy potential. Capturing that resource is part of a broader effort to reduce CO2 emissions. While few turbines have been constructed in U.S. waters, over a dozen currently planned offshore wind projects have the potential to displace marine birds, potentially leading to effective habitat loss. We focused on three diving birds identified in Europe to be vulnerable to displacement. Our research aimed to determine their potential exposure to areas designated or proposed for offshore wind development along the Atlantic OCS. Methods Satellite tracking technology was used to determine the spatial and temporal use and movement patterns of Surf Scoters (Melanitta perspicillata), Red‐throated Loons (Gavia stellata) and Northern Gannets (Morus bassanus), and calculate their exposure to each offshore wind area. We tagged 236 adults in 2012–2015 on the Atlantic OCS from New Jersey to North Carolina; an additional 147 birds tagged in previous tracking studies were integrated into our analyses. Tracking data were analysed in two‐week intervals using dynamic Brownian bridge movement models to develop composite spatial utilization distributions. For each species, these distributions were then used to calculate the spatio‐temporal exposure to each offshore wind area. Results Surf Scoters and Red‐throated Loons were exposed to offshore wind areas almost exclusively during migration because these species were distributed among coastal and inshore waters during winter months. In contrast, Northern Gannets ranged over a much larger area, reaching farther offshore and south in winter, thus exhibited the greatest exposure to extant offshore wind areas. Conclusions Results of this study provide better understanding of how diving birds use current and potential future offshore wind areas on the Atlantic OCS, and can inform permitting, risk assessment and pre‐ and post‐construction impact assessments of offshore energy infrastructure.
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Wind energy developments can be responsible for negative impacts on birds, including displacement. In this study we performed a systematic review of the literature available on bird displacement due to wind turbines, both onshore and offshore, to: (i) assess overall trends in scientific research; (ii) review the existing knowledge; and (iii) outline recommendations for future studies on this topic in order to overcome the major gaps and limitations found. Our results are based on 286 trials extracted from 71 peer-reviewed studies. The literature on this topic has increased in the past decade but is concentrated in Europe and United States, despite the fact that the wind industry has worldwide coverage. Open habitats—as agricultural fields and grasslands—were the most represented and Accipitriformes, Galliformes, Charadriiformes, Anseriformes and Passeriformes were the most frequently studied taxa. Displacement was recorded in 40.6% of the trials, and Gaviiformes, Anseriformes, Suliformes, Accipitriformes and Falconiformes were the most affected groups. Pelecaniformes, Passeriformes and Charadriiformes were the groups for which no significant effects were more often observed. We provide a list of recommendations, focused on study design, reporting and result dissemination, that should contribute to more robust conclusions of future studies on this topic.
Technical Report
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Environmental Impact Assessments (EIA) conducted during pre-construction phase of offshore wind farms clearly identified interactions between turbines and marine wildlife, especially seabirds, as a concern requiring further investigation. Mortality associated with collision could lead to negative impacts on seabird populations, and needs to be assessed on a case-by-case basis. Within environmental impact assessments, the Collision Vulnerability Index is frequently used to assess collision risk, and is based on several vulnerability factors among which flight height is the most critical. We therefore conducted a comprehensive literature review possible for the 81 species, including breeding and migrating birds, focusing on flight height and three others collision risk factors. We calculated an Uncertainty Level associated with flight height to take into account its reliability when calculating the Collision Vulnerability index. For approx. 20 species, the available information is satisfactory to assess flight heights. However, we identified 60 species for which further data collection is necessary to reduce uncertainty about vulnerability to wind turbine collisions, and identified existing GPS data which may facilitate further work. Within X-ROTOR, collision risk factors will be coupled with habitat use and conservation status into the Collision Vulnerability Index. This index will be applied to seabird distribution data to aid identification of suitable areas for the development of the X-ROTOR turbines.
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Understanding how breeding and non-breeding populations are geographically linked across seasons has important behavioral, demographic, and evolutionary implications for migratory animals. We used movement data collected from satellite-tagged Red-throated Loons (Gavia stellata) to provide new and more accurate information about spatial use during the full annual cycle for this species in eastern North America. We provide the first complete description of four migration routes used by Red-throated Loons along the U.S. mid-Atlantic coast and their northern breeding grounds. Despite sampling just 5% of the North American Atlantic coast non-breeding range, the birds we sampled exhibited a high degree of population spread across 65% of the breeding range, occurring across 44 degrees of longitude and 23 degrees of latitude. Network analysis identified core stopover areas with high population use and slower movement speeds, as well as migratory corridors associated with faster speeds and higher connectivity between core sites. Some of these high-use areas represent sites where environmental events could impact a majority of the sampled individuals, e.g., some of the migratory corridors and stopover locations were used exclusively by birds breeding in the far eastern breeding range. Our results underscore the possibility that spatial connectivity can exist between the migratory period and one stationary period even when there is not strong migratory connectivity as traditionally measured between stationary periods.
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Satellite tracking is of great importance for operational monitoring of the natural environment’s components. Here, telemetry is directly used, which is a set of technologies; it enables making remote measurements and gathering data that can be provided to the operator or user. The main goal of the research is to inform the reader on the ICARUS satellite telemetry project and the related current work in Russia. The ICARUS satellite telemetry system is an international development designed for studying the animal world, including its smallest specimens, and the environment as a whole. The authors consider the issue of processing and structuring large volumes of telemetric data for the purpose of their application in the tasks of operational visualization of animal movements. We present the structure of the data obtained through this system and describe software that allows its automated processing and uses it to form a spatial thematic database. The ultimate aim of the work is to create a web application that would provide the scientific community with ICARUS telemetry information and enable operational wildlife mapping.
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In Europe, the German Bight is one of the most important non-breeding areas for protected red-throated divers (Gavia stellata). It is unclear what attracts the birds to this area, especially as the food composition of seabirds outside the breeding season is notoriously difficult to study. To obtain information on prey species composition of red-throated divers in this area, faecal samples from 34 birds caught alive were analysed using DNA metabarcoding. Prey DNA was detected in 85% of the samples with a mean number of 4.2 ± 0.7 taxa per sample (n = 29). Altogether, we found a broad prey spectrum with 19 fish taxa from 13 families dominated by five groups: clupeids, mackerel, gadoids, flatfish and sand lances with clupeids being the most frequently detected prey. Our results indicate that red-throated divers are generalist opportunistic feeders in the German Bight, but pelagic schooling fish that aggregate at frontal zones and have a high energetic value might be favoured. Atlantic mackerel appears to be a more important prey for red-throated divers in this area than previously thought. The precision achievable using metabarcoding has revealed a number of prey species that are consumed by red-throated divers in the German Bight, which helps to explain the selection of this area by divers in winter and spring.
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The increasing demand for robust marine bird abundance and distribution assessments coupled with technological advances has led to the development of digital survey techniques for birds. Although digital surveys for bird monitoring are becoming a standard method in some countries, their strengths and weaknesses and comparability with traditional visual surveys remain insufficiently documented and understood. Aiming to improve existing knowledge on digital video monitoring techniques, we conducted one parallel digital video survey with 2-cm ground resolution and a 544-m swath flown at 549 m and an aerial visual survey flown at 76 m over the southern Baltic Sea in March 2015. We assessed bird sighting rates, identification rates, observed densities, and model-based abundance estimates. The digital survey covered a larger area through direct registrations, provided higher numbers of bird sightings and identified species, and higher spatial accuracy than the visual survey. Overall species identification rates were similar between the survey methods; however, there were marked differences among bird taxonomic groups: more individuals were identified to species level in the digital survey dataset for the majority of taxonomic groups, except for grebes and auks. These advantages supplement other previously identified benefits of digital aerial surveys, such as the elimination of bird disturbance due to high flight altitude, reduced observer bias, and availability of raw data for quality assurance. Furthermore, higher numbers of direct bird sightings at a higher spatial resolution during digital surveys ensure better statistical analyses, including distribution modelling, of more species for the same survey effort.
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Shipping is a growing source of air pollutants and greenhouse gases, which are emitted mainly over an international territory, the seas, for which only shared responsibility by all countries is felt. The international community, in particular the International Maritime Organisation, is called to look for appropriate mitigation of these emissions. This starts with the reporting of emissions in an inventory and its mapping over the international territory to be able to then evaluate the effect of emission reduction policies on the environment. Under the European Monitoring and Evaluation Programme, Member States are required to provide gridded emissions for the different sectors but the spatial allocation of ship emissions requires a supranational setup to avoid transboundary inconsistencies. By using vessel density maps extracted from historical Long Range Identification and Tracking (LRIT) data, accurate high-resolution maps of emissions can be obtained in support of policy development, implementation and monitoring in the interrelated fields of air quality and climate.
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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. There are increasing proposals for wind farms in UK waters and seabirds are a vulnerable group, which may be at risk from these developments. 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. 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 behaviour-time budget was similar to that of tracked gannets. 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. Synthesis and applications. Our spatially explicit individual-based models (IBM) highlight 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.
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Oceanic fronts are key habitats for a diverse range of marine predators, yet how they influence fine-scale foraging behaviour is poorly understood. Here, we investigated the dive behaviour of northern gannets Morus bassanus in relation to shelf-sea fronts. We GPS (global positioning system) tracked 53 breeding birds and examined the relationship between 1901 foraging dives (from time-depth recorders) and thermal fronts (identified via Earth Observation composite front mapping) in the Celtic Sea, Northeast Atlantic. We (i) used a habitat-use availability analysis to determine whether gannets preferentially dived at fronts, and (ii) compared dive characteristics in relation to fronts to investigate the functional significance of these oceanographic features. We found that relationships between gannet dive probabilities and fronts varied by frontal metric and sex. While both sexes were more likely to dive in the presence of seasonally persistent fronts, links to more ephemeral features were less clear. Here, males were positively correlated with distance to front and crossfront gradient strength, with the reverse for females. Both sexes performed two dive strategies: shallow V-shaped plunge dives with little or no active swim phase (92% of dives) and deeper U-shaped dives with an active pursuit phase of at least 3 s (8% of dives). When foraging around fronts, gannets were half as likely to engage in U-shaped dives compared with V-shaped dives, independent of sex. Moreover, V-shaped dive durations were significantly shortened around fronts. These behavioural responses support the assertion that fronts are important foraging habitats for marine predators, and suggest a possible mechanistic link between the two in terms of dive behaviour. This research also emphasizes the importance of cross-disciplinary research when attempting to understand marine ecosystems.
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The number of offshore wind farms in Europe and elsewhere has substantially increased in recent years. This rapid development has raised concerns about potential impacts on marine wildlife, particularly on seabirds, as these can be negatively affected through collision and displacement. While collision risk has been the focus of a number of studies, information about displacement of seabirds is scarce. Here we present data from an extensive survey program that aimed to determine the effects on seabirds of the first German offshore wind farm ‘alpha ventus’. Data were collected by line transect surveys during the first three years of operation. We found significant displacement of five species with 75% to 92% lower abundance inside compared to outside the wind farm. For three species, the response distance to the outermost turbines was estimated to exceed 1 km. Two gull species were attracted to the wind farm site. Our results and a review of the available literature revealed good agreement with respect to the sign of the response (avoidance vs. attraction) but considerable differences in the strength of the response and the spatial extent of the disturbance outside the footprint of wind farms. While it seems unlikely that small-scale displacement by single wind farms would have an impact at the population level, the extent of the proposed development of offshore wind energy warrants further research into cumulative effects and their biological significance for seabird populations.
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Information and understanding of fishing activities at sea are fundamental components of marine knowledge and maritime situational awareness. Such information is important to fisheries science, public authorities and policy makers. In this paper we introduce a first map at European scale of EU fishing activities extracted using Automatic Identification System (AIS) ship tracking data. The resulting map is a density of points that identify fishing activities. A measure of the reliability of such information is also presented as a map of coverage reception capabilities.
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Species distribution models in marine environments typically use static variables, partly due to the limited availability of fine-resolution dynamic predictor variables and sufficiently detailed species abundance data. Our aim was to describe and quantify the dynamic coupling between the distribution of marine species (seabirds) and the natural variability of their habitat in real time through the combination of a high-resolution hydrodynamic model, aerial digital surveys and real-time species distribution modelling. We used a 2-step (delta) generalized additive model at 500 m spatial resolution for assessment and prediction of the changing patterns of wintering red-throated divers (RTDs) Gavia stellata in the outer Thames estuary, United Kingdom. Our dynamic species distribution models successfully resolved the major oscillations in the distribution of RTDs and confirmed their tight association with frontal zones where the probability of prey encounter was higher. The relative model standard errors (%) were generally below 30% in the high-density areas. Area under the curve (AUC) values indicated that the models were capable of distinguishing presence from absence about 75% of the time. The predictive power of the achieved distribution models made it possible to accurately identify areas where RTDs were concentrated. Comparisons between visual aerial and digital stills aerial surveys documented that, in spite of similar patterns, the aerial digital surveys generally recorded significantly higher densities of RTDs than the visual aerial surveys. This study demonstrates how marine distribution models with assimilation of habitat variables from a well-calibrated fine-resolution hydrodynamic model coupled with the use of digital aerial surveys can facilitate the capture of detailed associations between seabirds and their dynamic habitats.
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Offshore wind turbines have been successfully deployed in Europe since 1991, providing thousands of megawatts of clean energy for multiple nations. Ten years ago, it seemed that the United States would follow suit: The US Energy Policy Act of 2005 directed the Department of the Interior (DOI) to establish an offshore leasing regime in federal waters (generally oceanic waters 3–200 nautical miles from the coast). It appeared to be a crucial step in opening the door to the country’s vast offshore wind resource: turbine installations in the Mid-Atlantic Bight alone could power all United States electricity, automobile transport, and building heat needs (1).
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Effective management and the maintenance of marine ecosystem services rely on a capacity to predict theecological consequences of environmental change and potential management interventions (Chapter 1). Making thesepredictions is difficult because anthropogenic stressors do not produce uniform or consistent impacts on biodiversity and ecosystem functioning. Rather, their effects can be modified by a variety of factors that cause them to vary among locations and different points in time. Thus, the effectiveness of actions taken to manage environmental problems is likely to vary in a similar way: interventions that are sufficient to mitigate a stressor's impacts in one situation might be inadequate or excessive in others. Both sound science and efficient management require us to recognise that spatial and temporal variability are inherent to natural systems, and that the ecosystem complexity places inherent limits on our ability to predict future ecological conditions. However, many ofthe causes of this variability have been identified. Careful consideration of these factors will enhance scientific understanding, improve ecological prediction and enhance our efforts to optimise marine policy and management by reducing the uncertainty associated with the effects of stressors.
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One of the most important wintering sites for Red-throated Divers Gavia stellata is the offshore zone of the German North Sea. The implementation of the EU Birds Directive in German offshore waters requires special protection of divers that comprise mainly Red-throated and Black-throated G. arctica Divers. An important first step concerning the protection was the establishment of two Special Protection areas for birds in the EEZ of the North and Baltic Seas in 2004. Anthropogenic activities at sea, such as the construction of offshore wind farms or ship traffic, have strong impacts on divers. In the course of the ongoing marine spatial planning it is particularly important to improve the knowledge on distribution patterns and phenology of divers in the German part of the North Sea. This publication presents the most recent analysis of spatio-temporal patterns of divers in the German North Sea. By merging data from scientific projects and environmental impact studies, the data basis could be considerably improved. Divers were recorded by ship-based and aerial surveys during 2000 to 2013. Distribution patterns on a 1 km x 1 km grid were interpolated using Generalized Additive Models. The first nameable aggregations of divers during the course of the year are found in the area of East Frisia during October. Abundance values increase constantly during the following weeks. Eventually, divers are found in the whole coastal zone of the German North Sea during the winter months. Areas of main abundance shift seawards during spring with high density areas occurring in and around the Special Protection Area “Eastern German Bight” off the island of Sylt. Several wind farm sites overlap with hot spots of diver distribution. The mean spring population of divers in the German North Sea was calculated at 20,000 individuals for the period 2002 to 2013. Numbers in spring did not significantly increase or decrease over this period. The most recent data on diver abundance reflect certain regional, annual variability that can most likely be explained by varying abundance in bentho-pelagic fish stocks as well as by variances in the hydrodynamic systems. The core aggregation of divers during spring could constantly be found within the region of the Special Protection Area “Eastern German Bight” over the course of the last years. However, most recent data still underline that the core area extends west outside the borders of the protected area. Some of the wind farms already established clearly overlap with the main distribution areas of divers.
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The European Unions' Marine Strategy Framework Directive aims to limit anthropogenic influences in the marine environment. But marine ecosystems are characterized by high variability, and it is not trivial to define its natural state. Here, we use the physical environment as a basis for marine classification, as it determines the conditions in which organisms must operate to survive and thrive locally. We present a delineation of the North Sea into five distinct regimes, based on multidecadal stratification characteristics. Results are based on a 51 year simulation of the region using the coupled hydrobiogeochemical model GETM-ERSEM-BFM. The five identified regimes are: permanently stratified, seasonally stratified, intermittently stratified, permanently mixed, and Region Of Freshwater Influence (ROFI). The areas characterized by these regimes show some interannual variation in geographical coverage, but are overall remarkable stable features within the North Sea. Results also show that 29% of North Sea waters fail to classify as one of the defined stratification regimes, due to high interannual variability. Biological characteristics of these regimes differ from diatom-based food webs in areas with prolonged stratification to Phaeocystis-dominated food webs in areas experiencing short-lived or no stratification. The spatial stability of the identified regimes indicates that carefully selected monitoring locations can be used to represent a substantive area of the North Sea.
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To gain further insight into the foraging behaviour of predator species, it is essential that interactions between predators, their prey and the surrounding environment are better understood. The primary purpose of this study was to determine the underlying processes, both physical and biological, driving variation in the times and locations of seabird foraging events. Using fine-scale simultaneous measurements of seabird abundance, prey density and oceanographic variability collected during an at-sea survey in the Firth of Forth region of the North Sea, zero-inflated negative binomial models were applied to identify the underlying processes driving foraging behaviour in 2 seabird species: the common guillemot Uria aalge and the black-legged kittiwake Rissa tridactyla. Both guillemot and kittiwake models showed consistency in their results; specific tidal states and thermal stratification levels explained observed increases in abundance. The secondary purpose of this study was to identify key oceanographic processes driving variability in prey density and determine if these were comparable to those underlying the behaviour of foraging seabirds. Log-transformations of 2 measures of prey density, NASC-40-50(MAX) and NASC-50-70(MAX), were modelled using generalised least squares. Similar tidal conditions and thermal stratification levels explained distributional patterns, suggesting that these processes act to increase prey availability, creating profitable foraging opportunities for predators to exploit. This has been termed the tidal coupling hypothesis and identifies that critical marine habitats occur not only at limited spatial locations but also within specific temporal intervals relating to the tidal cycle. Further more, by incorporating this oceanographic influence on foraging habitat, fine-scale predator-prey relationships were also identified. Foraging guillemots and kittiwakes displayed a Type II functional response to increasing values of NASC-40-50(MAX).
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Understanding how animals select for habitat and foraging resources therein is a crucial component of basic and applied ecology. The selection process is typically influenced by a variety of environmental conditions including the spatial and temporal variation in the quantity and quality of food resources, predation or disturbance risks, and inter- and intraspecific competition. Indeed, some of the most commonly employed ecological theories used to describe how animals choose foraging sites are: nutrient intake maximisation, density-dependent habitat selection, central-place foraging, and predation risk effects. Even though these theories are not mutually exclusive, rarely are multiple theoretical models considered concomitantly to assess which theory, or combination thereof, best predicts observed changes in habitat selection over space and time. Here, we tested which of the above theories best-predicted habitat selection of Svalbard-breeding pink-footed geese at their main spring migration stopover site in mid-Norway by computing a series of resource selection functions (RSFs) and their predictive ability (k-fold cross validation scores). At this stopover site geese fuel intensively as a preparation for breeding and further migration. We found that the predation risk model and a combination of the density-dependent and central-place foraging models best-predicted habitat selection during stopover as geese selected for larger fields where predation risk is typically lower and selection for foraging sites changed as a function of both distance to the roost site (i.e. central-place) and changes in local density. In contrast to many other studies, the nutritional value of the available food resources did not appear to be a major limiting factor as geese used different food resources proportional to their availability. Our study shows that in an agricultural landscape where nutritional value of food resources is homogeneously high and resource availability changes rapidly; foraging behaviour of geese is largely a tradeoff between fast refuelling and disturbance/predator avoidance.
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We developed and evaluated a surgical procedure for implanting intra-abdominal radiotransmitters with external whip antennas in captive mallards (Anas platyrhynchos). Transmitters were implanted in the abdominal cavity and the antennas exited through the caudal abdominal wall and skin. Birds with implanted transmitters developed mild to moderate localized air sac reactions. These reactions involved adhesions of the right anterior abdominal air sac to the liver with contractions around the transmitters and antenna catheters. The adhesions were reinforced by a proliferation of connective tissue and lined by multinucleated giant cells (foreign body reaction). Casual observation indicated that neither behavior nor activity of the birds was altered by the histological reaction to the transmitter implant. No increase in systemic lesions (particularly liver or kidney) could be correlated with the histological reactions. Our evaluations indicate that the procedure is a reliable method for radiomarking ducks and the technique has been successfully used in 2 field studies.
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Prior to the construction of an offshore wind farm at the Belgian Thorntonbank, local seabird abundance was studied by means of ship-based surveys. ‘Seabirds at sea’ count data, however, exhibit extreme spatial and temporal variation, impeding the detection of human impacts on seabird abundance and distribution. This paper proposes a transparent impact assessment method, following a before–after control–impact design and accounting for the statistical challenges inherent to ‘seabirds at sea’ data. By simulating a broad range of targeted scenarios based on empirical model coefficients, we tested its efficacy in terms of power and investigated how the chance of statistically detecting a change in numbers is affected by data characteristics, monitoring period and survey intensity. Because of high over-dispersion and/or zero inflation, the power to detect a 50% decrease in numbers was generally low, but did reach 90% within less than 10 years of post-impact monitoring for northern gannet (Morus bassanus) and common guillemot (Uria aalge).
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Offshore wind power provides a valuable source of renewable energy that can help reduce carbon emissions. Technological advances are allowing higher capacity turbines to be installed and in deeper water, but there is still much that is unknown about the effects on the environment. Here we describe the lessons learned based on the recent literature and our experience with assessing impacts of offshore wind developments on marine mammals and seabirds, and make recommendations for future monitoring and assessment as interest in offshore wind energy grows around the world. The four key lessons learned that we discuss are: 1) Identifying the area over which biological effects may occur to inform baseline data collection and determining the connectivity between key populations and proposed wind energy sites, 2) The need to put impacts into a population level context to determine whether they are biologically significant, 3) Measuring responses to wind farm construction and operation to determine disturbance effects and avoidance responses, and 4) Learn from other industries to inform risk assessments and the effectiveness of mitigation measures. As the number and size of offshore wind developments increases, there will be a growing need to consider the population level consequences and cumulative impacts of these activities on marine species. Strategically targeted data collection and modeling aimed at answering questions for the consenting process will also allow regulators to make decisions based on the best available information, and achieve a balance between climate change targets and environmental legislation.
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Marine management plans over the world express high expectations to the development of offshore wind energy. This would obviously contribute to renewable energy production, but potential conflicts with other usages of the marine landscape, as well as conservation interests, are evident. The present study synthesizes the current state of understanding on the effects of offshore wind farms on marine wildlife, in order to identify general versus local conclusions in published studies. The results were translated into a generalized impact assessment for coastal waters in Sweden, which covers a range of salinity conditions from marine to nearly fresh waters. Hence, the conclusions are potentially applicable to marine planning situations in various aquatic ecosystems. The assessment considered impact with respect to temporal and spatial extent of the pressure, effect within each ecosystem component, and level of certainty. Research on the environmental effects of offshore wind farms has gone through a rapid maturation and learning process, with the bulk of knowledge being developed within the past ten years. The studies showed a high level of consensus with respect to the construction phase, indicating that potential impacts on marine life should be carefully considered in marine spatial planning. Potential impacts during the operational phase were more locally variable, and could be either negative or positive depending on biological conditions as well as prevailing management goals. There was paucity in studies on cumulative impacts and long-term effects on the food web, as well as on combined effects with other human activities, such as the fisheries. These aspects remain key open issues for a sustainable marine spatial planning.
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The coastal waters off the southeastern United States (SEUS) are a primary wintering ground for the endangered North Atlantic right whale (Eubalaena glacialis), used by calving females along with other adult and juvenile whales. Management actions implemented in this area for the recovery of the right whale population rely on accurate habitat characterization and the ability to predict whale distribution over time. We developed a temporally dynamic habitat model to predict wintering right whale distribution in the SEUS using a generalized additive model framework and aerial survey data from 2003/2004 through 2012/2013. We built upon previous habitat models for right whales in the SEUS and include data from new aerial surveys that extend the spatial coverage of the analysis, particularly in the northern portion of this wintering ground. We summarized whale sightings, survey effort corrected for probability of whale detection, and environmental data at a semimonthly resolution. Consistent with previous studies, sea surface temperature (SST), water depth, and survey year were significant predictors of right whale relative abundance. Additionally, distance to shore, distance to the 22°C SST isotherm, and an interaction between time of year and latitude (to account for the latitudinal migration of whales) were also selected in the analysis presented here. Predictions from the model revealed that the location of preferred habitat differs within and between years in correspondence with variation in environmental conditions. Although cow-calf pairs were rarely sighted in the company of other whales, there was minimal evidence that the preferred habitat of cow-calf pairs was different than that of whale groups without calves at the scale of this study. The results of this updated habitat model can be used to inform management decisions for a migratory species in a dynamic oceanic environment.
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Survey data on seabird distribution at sea, hydrographic data and optical satellite data collected for the German Eight were used to analyse the variability of the distribution of wintering red-throated diver and black-throated diver Gavia stellata/arctica in relation to oscillations of the Jutland Coastal Current (JCC) and associated surface fronts. Data collected from hydrographic stations were summarised by means of principal component analysis; the first component, reflecting characteristics of the JCC, provided a satisfactory quantitative measurement of the average meso-scale habitat used by both species. The pelagic range of divers clearly followed the outer estuarine front between surface North Sea water and the JCC, which was located between the 20 and 30 m depth contours. Despite a highly transient trailing edge of the JCC, no divers were ever observed in North Sea water. Hydrographic as well as composited satellite CZCS (Coastal Zone Color Scanner) data indicated the presence of an inner front, spanning a stronger surface salinity gradient than the outer estuarine front. The inner estuarine front was located between mixed estuarine water, with salinities between 32 and 34 psu, and the core of the estuarine water mass from the river Elbe, with salinities below 32 psu. Seven-year composite images, produced from all available CZCS-Chl (chlorophyll) data taken over the German Eight during the Nimbus-7 mission, revealed the mean distribution of the inner estuarine front as a sharp gradient between the 15 and 20 m depth contours, extending less than 10 km in longitude. The variability of the inner estuarine front was measured over a series of cruises, and it indicated a quasi-stable structure; the prevailing position of the surface front was in a zone stretching from 07 degrees 30' E at Horns Reef (55 degrees 45' N) to 07 degrees 50' E south of Amrum Bank (54 degrees 30' N), except during easterly winds when the front was advected offshore as far as 6 degrees 50' E. The recorded patches of high densities of divers were almost confined to areas within 5 km distance from the mean frontal zone. The link between divers and the inner estuarine front seemed rather persistent, as peak densities coincided with the location of this front during all cruises, while lower densities were normally observed in the core Elbe water and in the mixed water outside the front. The authors suggest that the quasi-stability and strength of the inner estuarine front give rise to a predictable location of food resources (i.e, small fish) for divers in the German Eight. Our study highlights the potential for frontal structures of the JCC to influence the marine ecosystem of the southeastern North Sea.
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This paper gives the physical oceanography background for the Bremerhaven Workshop on Biological Effects of Contaminants in the North Sea. Two main conclusions must be drawn: (1) The German Bight is an area characterized by strong mesoscale variability in physical properties such as fronts, meanders and eddies. This variability is also seen in the mobile superficial sediment and the resulting variability of the suspended matter content. (2) During the workshop the hydrographic situation in the German Bight was marked by highly saline inflows to the German Bight from the English Channel. The stations close to the East-Friesian coast are located within the contaminated Continental Coastal Water; the more offshore stations met more or less undiluted water originating from the English Channel, with a high portion of Atlantic Water. -from Authors
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Research into the effects of scale on cetacean-habitat relationships is limited and has produced ambiguous results. We explored the effects of spatial resolution (a component of scale) on dolphin- habitat models using 4 yr of data collected in the eastern tropical Pacific Ocean (ETP). We developed generalized additive models of dolphin-habitat rela- tionships for 4 species at 6 spatial resolutions using oceanographic and geographic habitat variables. For all species, the ecological patterns in the models built at the different resolutions were similar: the same vari- ables frequently occurred at multiple resolutions and had similar functional forms, and maps of predicted distributions identified similar high and low density regions. Additionally, interannual habitat variability, which is most likely related to the El Niño-Southern Oscillation, had a greater impact on the predictive power of dolphin-habitat models than spatial resolu- tion. Although it is common to find scale dependence in species-habitat relationships, domains of scale exist in which ecological patterns do not change. The absence of scale dependence in the models for the 4 dolphin species suggests that resolutions from 2 to 120 km occur within a single domain of scale in the ETP. This domain of scale may be determined by the physical oceanography of the ETP, which is generally defined by large-scale processes. Although resolutions from 2 to 120 km appear to occur within a domain of scale, building models at the larger resolutions we investigated may reduce the noise in the data due to false absences.
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Background The movement of animals is strongly influenced by external factors in their surrounding environment such as weather, habitat types, and human land use. With advances in positioning and sensor technologies, it is now possible to capture animal locations at high spatial and temporal granularities. Likewise, scientists have an increasing access to large volumes of environmental data. Environmental data are heterogeneous in source and format, and are usually obtained at different spatiotemporal scales than movement data. Indeed, there remain scientific and technical challenges in developing linkages between the growing collections of animal movement data and the large repositories of heterogeneous remote sensing observations, as well as in the developments of new statistical and computational methods for the analysis of movement in its environmental context. These challenges include retrieval, indexing, efficient storage, data integration, and analytical techniques. Results This paper contributes to movement ecology research by presenting a new publicly available system, Environmental-Data Automated Track Annotation (Env-DATA), that automates annotation of movement trajectories with ambient atmospheric observations and underlying landscape information. Env-DATA provides a free and easy-to-use platform that eliminates technical difficulties of the annotation processes and relieves end users of a ton of tedious and time-consuming tasks associated with annotation, including data acquisition, data transformation and integration, resampling, and interpolation. The system is illustrated with a case study of Galapagos Albatross (Phoebastria irrorata) tracks and their relationship to wind, ocean productivity and chlorophyll concentration. Our case study illustrates why adult albatrosses make long-range trips to preferred, productive areas and how wind assistance facilitates their return flights while their outbound flights are hampered by head winds. Conclusions The new Env-DATA system enhances Movebank, an open portal of animal tracking data, by automating access to environmental variables from global remote sensing, weather, and ecosystem products from open web resources. The system provides several interpolation methods from the native grid resolution and structure to a global regular grid linked with the movement tracks in space and time. The aim is to facilitate new understanding and predictive capabilities of spatiotemporal patterns of animal movement in response to dynamic and changing environments from local to global scales.
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Management and conservation of populations of animals requires information on where they are, why they are there, and where else they could be. These objectives are typically approached by collecting data on the animals' use of space, relating these positional data to prevailing environmental conditions and employing the resulting statistical models to predict usage at other geographical regions. Technical advances in wildlife telemetry have accomplished manifold increases in the amount and quality of available data, creating the need for a statistical framework that can use them to make population-level inferences for habitat preference and space-use. This has been slow-in-coming because wildlife telemetry data are spatio-temporally autocorrelated, often unbalanced, presence-only observations of behaviourally complex animals, responding to a multitude of cross-correlated environmental variables.
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The effect of human disturbance on animals is frequently measured in terms of changes in behaviour in response to human presence. The magnitude of these changes in behaviour is then often used as a measure of the relative susceptibility of species to disturbance; for example species which show strong avoidance of human presence are often considered to be in greater need of protection from disturbance than those which do not. In this paper we discuss whether such changes in behaviour are likely to be good measures of the relative susceptibility of species, and suggest that their use may result in confusion when determining conservation priorities.
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Radiotelemetry is an essential tool in the study of free-ranging bird populations, and a variety of transmitter-attachment methods have been developed. A promising new method is abdominal implantation of a transmitter with a percutaneous antenna. Researchers using this technique should be concerned about and aware of mortality during surgery and during the immediate post-release period (the 14-day period following surgery). Of 307 radio-implant surgeries performed between 1995 and 1997 in harlequin ducks (Histrionicus histrionicus), 7 (2.3%) deaths were documented during surgery or anesthetic recovery. Of 295 birds released with implanted radios, 10 (3.4%) died during the immediate post-release period. Modifications to anesthetic procedures used in the 204 surgeries performed in 1996 and 1997 reduced mortality to 1.5% during surgery and 1.5% during the immediate post-release period. Anesthetic modifications included intubation of all birds, placement of birds on an elevated platform that allowed the head to rest at a level lower than the body during surgery, placement of a heated water blanket under the birds during surgery, monitoring of body temperature, and use of electrocardiogram and Doppler ultrasound to monitor heart rates and arrhythmias. Low levels of mortality associated with abdominal implantation of radio transmitters may be unavoidable, but mortality can be minimized with adjustments to anesthetic technique.