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Satellite telemetry and digital aerial surveys show strong displacement of red-throated divers (Gavia stellata) from offshore wind farms
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.
... The key species in the designation of this SPA 'Eastern German Bight' are the red-throated loon Gavia stellata and the black-throated loon G. arctica (Garthe et al. 2012). Both these species use the area for wintering, but mainly use it as a spring staging area (Garthe et al. 2015;Heinänen et al. 2020;Kleinschmidt et al. 2022), before migrating to their breeding grounds towards Greenland, Svalbard, Scandinavia, and northern Siberia (Kleinschmidt et al. 2022). Both species are listed in Annex 1 of the European Birds Directive as species in need of special protection. ...
... The offshore windfarm (OWF) 'Butendiek', located inside the SPA 'Eastern German Bight', as well as four other OWFs located just outside this SPA, were controversial from the outset, given that loons had already been shown to avoid OWFs over a wide area, resulting in substantial habitat loss (Petersen et al. 2006;Percival 2014). A series of studies on the spatial distribution of loons was therefore conducted in this area after installation of the OWFs, which confirmed strong avoidance of the OWFs by loons (Mendel et al. 2019;Heinänen et al. 2020;Vilela et al. 2020;Dierschke and Mercker, 2022;Garthe et al. 2023). ...
... Previous studies have gathered data on the displacement effects of OWFs on loons (Mendel et al. 2019;Heinänen et al. 2020;Vilela et al. 2020;Garthe et al. 2023), and no new analysis of this effect was therefore performed in this study. We calculated the area of the SPA Eastern German Bight affected by displacement effects, based on the distances calculated in these previous studies. ...
... Red-throated divers are known to be sensitive to disturbance caused by offshore wind farms, which leads to displacement from their foraging areas (Dierschke et al. 2016;Furness et al. 2013;Halley & Hopshaug 2007;Heinänen et al. 2020;Irwin et al. 2019;Mendel et al. 2019;Percival 2014;Petersen et al. 2006;Welcker & Nehls 2016), with evidence of displacement effects up to 8 to 20 km from the edge of an offshore wind farm (Heinänen et al. 2020;Mendel et al. 2019;SNCBs 2022;Vilela et al. 2020;Webb et al. 2016). Red-throated divers favour marine areas with shallow seas and sandy substrate (e.g. ...
... Red-throated divers are known to be sensitive to disturbance caused by offshore wind farms, which leads to displacement from their foraging areas (Dierschke et al. 2016;Furness et al. 2013;Halley & Hopshaug 2007;Heinänen et al. 2020;Irwin et al. 2019;Mendel et al. 2019;Percival 2014;Petersen et al. 2006;Welcker & Nehls 2016), with evidence of displacement effects up to 8 to 20 km from the edge of an offshore wind farm (Heinänen et al. 2020;Mendel et al. 2019;SNCBs 2022;Vilela et al. 2020;Webb et al. 2016). Red-throated divers favour marine areas with shallow seas and sandy substrate (e.g. ...
... Although it is unclear how adaptable each distinct population is (two years of data with overall low sample sizes), the variation in strategies and behavioural budgets suggests that RTDs as a species have the ability to adapt and adjust their behaviour to reflect environmental conditions during the winter period. This does however need to be considered alongside evidence that suggests displacement effects can be detected up to 8 to 20 km from the edge of an offshore wind farm (Heinänen et al. 2020;Mendel et al. 2019;SNCBs 2022;Vilela et al. 2020;Webb et al. 2016), reiterating the requirement for alternative suitable habitat to be available to accommodate and fulfil the foraging needs of any displaced birds. ...
The Red-throated Diver Energetics Project aimed to obtain empirical data on red-throated diver foraging behaviour during the non-breeding season. This report summarises the overall results from the project.
This report summarises the overall results from the Red-throated Diver Energetics Project, presenting novel data on wintering location and foraging behaviour from red-throated divers tagged in southern Finland, north Scotland (Orkney and Shetland) and north-east Iceland, along with discussion and interpretation of the results in the context of offshore wind development, further recommendations and a list of additional project outputs.
... Loons (divers, family Gaviidae) belong to the most sensitive group of species with respect to the avoidance of OWFs, as shown by studies of single or small groups of OWF sites in the North Sea, with significant negative effects on loon abundance up to 16 km from the outer edges of OWFs (e.g. ref. 17,[23][24][25][26] ). Furthermore, loons are very sensitive to ship traffic, with long flush distances in front of approaching vessels and significantly lower densities in areas with permanently higher ship traffic 27,28 . ...
... The large-scale and long-term data used in this study allowed the first species-specific, comprehensive view of the establishment of OWFs in the marine environment. It confirmed the findings for single OWFs or smaller clusters 17,25 , and revealed a redistribution of loons at a much larger scale (beyond single OWF clusters; see also 26 ). Birds aggregated within their original distribution area, but as far away from the OWFs as possible. ...
... 35 ; for a hydrographic description see ref. 36 ). However, recent telemetry data from our study area showed that some individuals preferred more coastal waters with lower salinity, while others preferred offshore areas with higher salinity, potentially reflecting individual foraging-site fidelity 25 . When foraging for their highly mobile prey, loons are now more restricted in terms of their larger-scale movements because their former foraging area has been split into smaller units by the establishment of several OWFs. ...
The North Sea is a key area worldwide for the installation of offshore wind farms (OWFs). We analysed data from multiple sources to quantify the effects of OWFs on seabirds from the family Gaviidae (loons) in the German North Sea. The distribution and abundance of loons changed substantially from the period before to the period after OWF construction. Densities of loons were significantly reduced at distances of up to 9–12 km from the OWF footprints. Abundance declined by 94% within the OWF + 1 km zone and by 52% within the OWF + 10 km zone. The observed redistribution was a large-scale effect, with birds aggregating within the study area at large distances from the OWFs. Although renewable energies will be needed to provide a large share of our energy demands in the future, it is necessary to minimize the costs in terms of less-adaptable species, to avoid amplifying the biodiversity crisis.
... 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. ...
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.
... 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). ...
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.
... Red-throated divers are susceptible to anthropogenic threats such as disturbance from shipping and offshore wind farms (Mendel et al. 2019;Heinänen et al. 2020;Garthe et al. 2023) and so there is an increasing interest in their habitat use and foraging behaviour (Dunn et al. 2024). The lack of knowledge regarding red-throated diver post-breeding foraging ecology is particularly concerning due to this likely being a time when they experience increased exposure to risks (Dierschke et al. 2017). ...
... We therefore demonstrate that, following initial work to understand how isotopic values vary between foraging behaviours and habitats, using feathers samples has benefits to increase our understanding of the frequency of differing foraging strategies. This minimally invasive technique could therefore be particularly valuable when investigating populations that are at risk of decline, such as those where there is concern that anthropogenic activity may deter individuals from their foraging habitats (Heinänen et al. 2020). In addition to being a minimally invasive way of investigating such populations, feather sampling for stable isotope analysis could also have applications for species conservation and protection, particularly where threats may vary depending on habitat use. ...
Understanding the habitat use of individuals can facilitate methods to measure the degree to which populations will be affected by potential stressors. Such insights can be hard to garner for marine species that are inaccessible during phases of their annual cycles. Here, we quantify the link between foraging habitat and behaviour in an aquatic bird of high conservation concern, the red‐throated diver (Gavia stellata) across three breeding populations (Finland, Iceland and Scotland) during their understudied moult period. Specifically, we quantify the relationship between feather isotope values (δ¹³C and δ¹⁵N) and diving behaviour, within and between populations, examining the use of intra‐depth zone (IDZ) dives as a proxy for benthic foraging. We found a strong positive relationship between both higher δ¹⁵N values and, to a lesser extent, δ¹³C values and the proportion of IDZ dives. This relationship was consistent across all three populations, but the baseline δ¹³C values varied between them, indicative of the populations' different moulting areas. Our results demonstrate that red‐throated divers continue to be generalist foragers after their breeding seasons, and that behavioural flexibility varies within and between populations. Furthermore, due to the existence of these relationships, we reveal the potential of stable isotope analysis as a standalone tool for monitoring changes in habitat use in this ecologically significant species. The approach may also apply to other generalist foragers that are known to use multiple foraging strategies (e.g., foraging benthically and pelagically), with implications for future conservation efforts.
... 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. ...
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.
... 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. ...
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.
... 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). ...
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.
... In contrast, however, other species, such as black-legged kittiwakes Rissa tridactyla, northern gannets Morus bassanus, Sandwich terns Thalasseus sandvicensis and lesser black-backed gulls Larus fuscus often fly at heights that present a collision risk [11,14], and are thus considered to be key species at risk of collision mortality in European waters [10]. In addition, some seabirds, such as red-throated divers Gavia stellata, show strong avoidance of offshore wind farms [15][16][17]. Others, such as auks, show limited or inconsistent avoidance [12,18,19]. Avoidance of turbines and other structures may reduce the available feeding habitat and/or increase the energy expenditure for birds that choose to fly around, rather than through, offshore wind farms [20,21]. ...
Offshore wind farms generate electricity at relatively low cost and are regarded as a major contributor to net zero targets, supporting United Nations Sustainable Development Goals 7 and 13. However, some seabird species are at risk of colliding with turbine blades or being displaced by offshore wind farms. The European Union and the UK have legal requirements for wind farm developers to implement compensation measures if their developments are likely to have an adverse impact on the integrity of seabird populations in Special Protection Areas. Compensation measures that have been established have carbon costs and are applicable only to a restricted group of species, reducing the overall benefits. Here we make a novel suggestion that placement of seaweed farms close to selected seabird colonies could act as compensation for mortality associated with offshore wind farms. Many seabirds construct nests from seaweed that they collect at sea. These birds may also use plastic waste in nest construction. Plastic can kill seabirds by entanglement. Increasing availability of seaweed could reduce this mortality by reducing use of plastic in nest construction. This novel approach has multiple advantages over other forms of compensation. In particular it could benefit northern gannets Morus bassanus, a species considered especially at risk from impacts of offshore wind farms but not addressed by existing compensation measures. Seaweed farming as a compensation measure could also contribute to carbon sequestration and provide other environmental benefits as well as promoting the growth of an industry not yet well established in European seas.
... Taxonomic, functional, and phylogenetic diversity all decreased with increasing wind turbine density, and hierarchical partitioning also showed that wind turbine density had the greatest independent contribution to explaining taxonomic diversity (48.240%), functional diversity (33.076%), and phylogenetic diversity (50.167%, Figure 5, and Supplementary Table S7), suggesting that wind farms play a crucial role and have significant negative effects on waterbird diversity. These results were in accord with studies in marine and mountain ecosystems (Dohm et al. 2019;Heinänen et al. 2020). Discrepancies in birds' sensitivities in response to wind farms may explain our results. ...
Ongoing wind energy developments play a key role in mitigating the global effects of climate change and the energy crisis; however, they have complex ecological consequences for many flying animals. The Yellow Sea coast is considered as an ecological bottleneck for migratory waterbirds along the East Asian–Australasian flyway (EAAF), and is also an important wind farm base in China. However, the effects of large-scale onshore wind farms along the EAAF on multidimensional waterbird diversity, and how to mitigate these effects, remain unclear. Here we examined how wind farms and their surrounding landscapes affected multidimensional waterbird diversity along the Yellow Sea coast. Taxonomic, functional, and phylogenetic diversity of the waterbird assemblages, and mean pairwise distances and nearest taxon distances with null models were quantified in relation to four different wind turbine densities. We also measured six landscape variables. Multi-dimensional waterbird diversity (taxonomic, functional, and phylogenetic diversity) significantly decreased with increasing wind turbine density. Functional and phylogenetic structures tended to be clustered in waterbird communities, and environmental filtering drove waterbird community assemblages. Furthermore, waterbird diversity was regulated by a combination of wind turbine density and landscape variables, with edge density of aquaculture ponds, in addition to wind turbine density, having the greatest independent contribution to waterbird diversity. These results suggest that attempts to mitigate the impact of wind farms on waterbird diversity could involve the landscape transformation of wind farm regions, e.g., by including high-edge-density aquaculture ponds (i.e. industrial ponds) around wind farms, instead of traditional low-edge-density aquaculture ponds.
... Divers Gavia spp. have been shown to avoid OWFs in their over-wintering and spring migration areas, with cumulative effects from multiple OWFs resulting in areas of functional exclusion from a substantial proportion of the otherwise available habitat (Mendel et al. 2019;Heinänen et al. 2020). Similarly, common eider Somateria mollissima and pinkfooted geese Anser brachyrhynchus have been shown to avoid entering OWFs during migration (Masden et al. 2009;Plonczkier and Simms 2012). ...
Offshore wind farms (OWFs) are a key part of efforts to mitigate the impacts of climate change. However, they have the potential to negatively impact seabird species through collisions with turbine blades, displacement from preferred foraging habitat and the perception of wind farms as a barrier to migrating or foraging birds. Whilst the data available to model these impacts are increasing, many data gaps remain, particularly in relation to the impacts of barrier effects. We analyse the movements of Sandwich terns in relation to an offshore wind farm cluster using data collected as part of a multi-year GPS tracking study. Over the course of the study, two additional wind farms were built within the home range of the breeding colony. The construction of these wind farms coincided with a change in the foraging and commuting areas used by breeding terns. Whilst birds entered OWFs when foraging, they appeared to avoid them when commuting, driving an apparent ‘funnelling’ effect to important feeding locations. We discuss if this could be driven by changes to the prey base, subsequent displacement and potentially altered routes reflecting new favourable airflow patterns following OWF construction. Our results suggest that behavioural responses of birds to OWFs may be the result of a complex series of ecological and environmental interactions, as opposed to simplistic assumptions around the perception of the OWF as a barrier to movement.
... Therefore, this distributional approach suffers from the conflation of both natural variability and knowledge uncertainty. Until recently, accurately estimating the proportion of birds displaced has proved challenging (but see Heinänen et al., 2020;Peschko et al., 2020a, b, Peschko et al., 2021, with natural variability in the marine environment compounding the difficulty in quantifying displacement rates. Historically, this prob-lem has been exacerbated by inconsistent approaches, low statistical power (Maclean et al., 2013), and poor design of postconstruction monitoring studies (Marine Management Organization, 2014). ...
Governments worldwide are setting ambitious targets for offshore renewable energy development (ORD). However, deployment is constrained by a lack of understanding of the environmental consequences of ORD, with impacts on protected birds forming a key environmental consenting challenge. Assessing the impacts of ORD on marine birds is challenging, utilizing interlinked approaches to understand complex behavioural, energetic, and demographic processes. Consequently, there is considerable uncertainty associated with ORD assessments for marine birds, with current methods failing to quantify uncertainty in a scientifically robust, evidence-based manner. This leads to a high degree of precaution and a lack of confidence in the evidence used to inform ORD consenting decisions. We review the methods used to estimate ornithological ORD impacts in the UK, a country at the forefront of ORD. We identify areas in which uncertainty quantification could be improved through statistical modelling, data collection, or adaptation of the assessment process. We develop a framework for end-to-end quantification of uncertainty, integrating uncertainty estimates from individual stages of the assessment process. Finally, we provide research recommendations to better quantify and reduce uncertainty, to lower future ORD consenting risk. These recommendations extend beyond the UK and could improve impact assessments in other countries with different legislative frameworks.
... This means selecting the safest turbine design, installing early warning systems to reduce the risk of collision, among other measures (Bennun et al., 2021;Maxwell et al., 2022). Substantial evidence of OWFs impacts, particularly on birds, include collisions (Masden and Cook, 2016), barrier or displacement effects which causes habitat loss and disruption of flight routes (Cook et al., 2018;Heinänen et al., 2020), change in breeding or feeding sites (Dierschke et al., 2016;Peschko et al., 2021), attraction (Rodríguez et al., 2019), and trophic cascades (Raoux et al., 2017;Pezy et al., 2020). However, few studies have analyzed the effects of OWFs on the pelagic ecosystem, and even fewer have involved targeted fieldwork (Abramic et al., 2022). ...
The increasing number of offshore wind farms (OWFs) proposed off the Brazilian coast is a biodiversity management challenge that needs to be addressed with strategic and targeted environmental impact assessments. The effects of OWFs on birds are much better studied in the northern than southern hemisphere. Knowledge of species distributions is key to developing effective conservation strategies. Ecological niche modeling can support strategic siting decisions and identify the target species for which mitigation of the impacts of OWFs may be required. We used the maximum entropy algorithm (MaxEnt) for modeling species niche suitability, incorporating environmental variables and presence-only data from tracking and at-sea surveys for seven albatrosses and petrels, of which five are threatened by extinction. We used the predicted niche suitability index (NSI) to calculate niche overlaps, assess distribution patterns and generate spatial prioritizations across seasons based on a species richness index (RI). Atlantic Yellow-nosed Albatross Thalassarche chlororhynchos, Atlantic Petrel Pterodroma incerta, and Great Shearwater Ardenna gravis were selected as target species for monitoring in Brazilian shallow waters (0 to 200 m depth) in the warm season, and Atlantic Yellow-nosed Albatross and White-chinned Petrel Procellaria aequinoctialis in the cold season. The RI was higher in waters between 200 m to 1000 m depth, a preferred area for OWFs with floating foundations. We advocate for the incorporation of niche models in environmental impact studies, as a tool for improving conservation, environmental planning, and impact assessment.
... 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. ...
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.
... 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. ...
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. ...
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. ...
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. ...
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.
... 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. ...
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
... 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). ...
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.
Bycatch, the incidental capture of non-target species in fishing gear, has been recognised as the most significant global conservation threat affecting seabird species. Geographically, bycatch rates vary widely, depending on local fishing efforts, environmental features, and seabird community composition. Regional and local research is essential due to the complexity of accurately extrapolating general conclusions regarding the impacts of bycatch. Existing European bycatch research predominantly focuses on northern regions, leaving a significant knowledge gap regarding bycatch in the Mediterranean Sea. This work presents findings of wintering diving seabirds as bycatch of small-scale fisheries in a coastal area of the northern Adriatic Sea, based on data collected between 2021 and 2023. Seabird distribution varied along the depth profile. The bathymetric range between 3 m and 5 m was the most exploited by fishermen. Bycatch of seabirds was confirmed in the study area, with five species recorded, i.e. Black-necked Grebe Podiceps nigricollis, Red-throated Loon Gavia stellata, Black-throated Loon Gavia arctica, Mediterranean Shag Gulosus aristotelis desmarestii, and Great Crested Grebe Podiceps cristatus. Our results suggest that bathymetry likely plays a strong influence on bycatch occurrence. Incidental captures were not widespread but appeared concentrated in the shallowest depths <5 m and the range <2.5 m was identified as particularly susceptible due to the low associated fishing effort and the majority of bycatch events recorded. We estimate that between 46 and 108 birds were incidentally captured during the research period. This study identifies key factors shaping the areas of bycatch vulnerability and risk, proposing a spatial–temporal mitigation framework within Natura 2000 sites and highlighting the value of local stakeholders’ engagement.
With the rapidly increasing intensity of human activities in the marine realm, it has become urgent to better understand the impacts of human-induced disturbances on marine species. Marine mammals and birds are often observed to alter their fine-scale spatial distribution patterns in the presence of human at-sea activities, such as ship traffic and offshore wind farms (OWFs). This study presents EPIC (Extensive Periphery for Impact and Control), a novel approach for investigating such displacement in marine megafauna. The approach consists of a survey design that uses the OWFs surroundings in all directions as control space, complemented by a sophisticated statistical approach to quantify the extent and intensity of displacement and habitat loss in and around the area of potential disturbance. The approach is showcased by investigating the effects of an OWF in the Dutch North Sea on the habitat use of razorbills (Alca torda) and common guillemots (Uria aalge), two seabird species that occur in large numbers across the North Sea. We used an explicit spatial-temporal Bayesian model to predict their spatial distribution patterns based on eight aerial surveysed. The model output is used for a simulation study, comparing bird densities in the potential impact area with 1000 similarly sized control areas from the peripheral control space and from these, displacement around the OWF. Strong displacement was found for both razorbills and guillemots, within the OWF footprint but also in its surroundings. Razorbill and guillemot densities inside the OWF were reduced by 0.953 and 1.604 individuals per km2, respectively, compared to the remainder of the study area, remaining considerably lower than control densities up to 2 km and > 10 km distance. The presented methodological approach holds great potential for future studies on the effects of local disturbances on displacement of marine megafauna.
Offshore wind energy development (OWED), while a key strategy for reducing carbon emissions, has potential negative effects to wildlife that should be examined to inform decision making and adaptive management as the industry expands. We present a conceptual framework to guide the long-term study of potential effects to birds and bats from OWED. This framework includes a focus on exposure and vulnerability as key determinants of risk. For birds and bats that are exposed to OWED, there are three main effects of interest that may impact survival and productivity: 1) collision mortality, 2) behavioral responses, including avoidance, displacement, and attraction, and 3) habitat-mediated effects to prey populations. If these OWED effects cause changes in survival and/or breeding success (e.g., fitness), they have the potential for population-level consequences, including changes in population size and structure. Understanding the influence of ecological drivers on exposure and effect parameters can help to disentangle the potential impacts of OWED from other stressors. We use this theoretical framework to summarize existing relevant knowledge and identify current priority research questions (n=22) for the eastern United States, where large-scale development of OWED is primarily in the planning and early construction phase. We also identify recommendations for study design and further prioritization of research topics.
The climate crisis is driving a rapid increase in size and number of offshore wind farms to reduce carbon emissions from electricity generation. However, there are concerns about the potential impact of offshore wind farms on the marine environment. Seabirds are considered to be at risk of being displaced from preferred foraging habitat, by construction and operation of offshore wind farms, resulting in reduced energy intake or elevated energetic costs and consequent decreases in survival and/or productivity. Typically, displacement or avoidance behaviour is assessed by comparing abundance and spatial distributions of seabirds before and after an offshore wind farm is constructed. However, seabird distributions are highly variable through time and space and so discerning a change in distribution caused by an offshore wind farm from other environmental variables can be challenging. We present a new method that controls for temporal variation by examining the location of individual seabirds relative to turbines. Mean seabird density at different distances from individual turbines (0-400m) was calculated from data collected on a total of 12 digital aerial surveys of the Beatrice Offshore Wind Farm (UK), in May-August in 2019 and 2021. Mean densities of common guillemot (Uria aalge), razorbill (Alca torda), Atlantic puffin (Fratercula arctica) and black-legged kittiwake (Rissa tridactyla), both flying and sat on the water, were calculated. If the presence of turbines had no effect on seabird distribution, there should be no relationship between distance from turbine and seabird density. This was tested by simulating a relocation of turbines, relative to seabird distribution, and recalculating seabird density over 0-400m from simulated turbine locations. This was repeated to generate a bootstrapped distribution of expected densities against which observed density was compared. If displacement was occurring, mean observed density close to turbines would be significantly lower than expected density, derived from the bootstrap distribution. Overall, observed mean density did not differ significantly from expected density, i.e. no displacement effect was detected. There was a slight tendency for guillemot and razorbill, when sat on the water, to be at higher densities than expected, near turbines, suggestive of possible attraction to turbines, and for flying birds to be at lower densities than expected, near turbines, suggestive of possible avoidance. No flying razorbills were recorded within 100m of turbines but sample sizes were small. Kittiwake tended to show no avoidance or attraction behaviour, although flying kittiwake density was slightly lower than expected at 200m from turbines. Puffins sat on the water were recorded in densities similar to the expected density. Overall, no effect of turbine rotor speed was found, i.e. birds were not more likely to be displaced/avoid turbines at higher or lower rotor speeds. The results of the turbine relocation analysis gave a more consistent and more easily interpreted assessment of displacement/avoidance behaviour than the typical approaches of comparing abundance and seabird distribution through time. We strongly encourage application of this new approach to post-construction spatial distribution data from other offshore wind farms, to build the evidence base on the effects of offshore wind farms on seabirds.
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.
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.
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.
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.
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.
Exploiting wind energy at sea offers an attractive source of renewable energy avoiding problems on land, but what are the consequences for birds? We review the Danish and European experience of offshore (i.e. marine) windfarms and the effects and impacts which we consider they may have on birds, primarily through barriers to movement, displacement from ideal feeding distributions and collision mortality. We use case studies to demonstrate examples of displacement effects among species such as Red-throated Diver Gavia stellata, Common Scoter Melanitta nigra and Long-tailed Duck Clangula hyemalis but are unable to determine their causes or whether these patterns have population level impacts, assessment of which remains a major challenge. There is accumulating evidence for widespread avoidance of offshore turbines by large-bodied birds at macro-, meso-and micro-scales, but we accept that our knowledge for smaller bird species is less adequate. We conclude that careful siting during the planning phase can avoid a multitude of potential conflicts with avian populations and that despite generally inadequate post-construction monitoring (especially during periods of unusual weather), experience shows low levels of collision rates, especially among long-lived large-bodied bird species considered most at risk. We lack any understanding of the impacts of barrier effects and displacement from favoured feeding areas, but on a single project basis, these impacts to date are considered insignificant at the population level because of the relatively small numbers of birds so affected. Based on experiences from multiple single site studies, it is essential that site specific impact assessments continue to be undertaken to establish the potential effects and impacts of each project development. However, we also urge a more strategic national and international approach to identification, assessment and selection process for sites for potential future development of offshore windfarms. Despite low-level impacts on an individual windfarm basis, cumulative impacts of multiple offshore windfarm development (especially spanning the length of population flyways) have yet to be adequately determined. Developing effective mechanisms to deliver such assessments remains an urgent requirement for the immediate future.
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.
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.
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.
Individual‐based models ( IBM s) 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.
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.
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.
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.
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.
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).
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.
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.
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.
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).
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.
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.
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).
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.
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.
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.
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.
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
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.
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.
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.
We review the evolution of regression models for the analysis of space‐use and habitat preference and outline the essential features of a framework that emerges naturally from these foundations. This allows us to derive a relationship between usage of points in geographical space and preference of habitats in environmental space. Within this framework, we discuss eight challenges, inherent in the spatial analysis of telemetry data and, for each, we propose solutions that can work in tandem. Specifically, we propose a logistic, mixed‐effects approach that uses generalized additive transformations of the environmental covariates and is fitted to a response data‐set comprising the telemetry and simulated observations, under a case‐control design.
We apply this framework to a non‐trivial case‐study using satellite‐tagged grey seals Halichoerus grypus from the east coast of Scotland. We perform model selection by cross‐validation and confront our final model's predictions with telemetry data from the same, as well as different, geographical regions. We conclude that, despite the complex behaviour of the study species, flexible empirical models can capture the environmental relationships that shape population distributions.
Generalized Additive Models (GAMs) were used, to test the hypothesis that trends in herring abundance are related to the location of ocean fronts and the temperature based variability of the northern North Sea ecosystem. Data from July of 4 years (1992 to 1995), collected during the ICES coordinated herring acoustic surveys (ICES Division IVa), were examined. It was found that geographic position and water mass characteristics influence the temporal distribution patterns of herring. The 2-stage modelling approach undertaken in the present study conveyed additional insights into the ecological behaviour of herring in the area. Temperature and depth of the thermocline, sea surface temperature, temperature difference between sea surface and seabed, and spatial location appeared to be key factors that modulate both presence and relative abundance of herring within the northern North Sea. Herring encounter was more probable in areas with cooler surface waters in the south than in the north, these areas having deeper thermoclines and temperatures at 60 m around 10 degrees C. Results indicated that areas with higher probability of finding herring present were also located in well-mixed waters and transition zones between frontal and stratified waters. The largest herring aggregations were consistently observed in the same areas. Herring appeared to avoid the cold bottom waters of the North Sea during the summer, probably due to the relatively poor food resources there. The pronounced similarity and stability in the multiyear relationship between prespawning herring abundance, its spatial distribution and ocean environmental conditions, with and without the zero observations, support the hypothesis that the observed relationships are authentic and characteristic of the stock.
Marine wind farms have attracted substantial public interest. The construction of wind facilities offshore may become Europe's most extensive technical development in marine habitats. Due to political pressure to complete construction soon, assessments of possible wind farm locations, for example in the German sectors of the North Sea and Baltic Sea, have to be based on existing knowledge.
In this study, we developed a wind farm sensitivity index (WSI) for seabirds. We applied this index to the Exclusive Economic Zone and the national waters of Germany in the North Sea. We chose nine factors, derived from species’ attributes, to be included in the WSI: flight manoeuvrability; flight altitude; percentage of time flying; nocturnal flight activity; sensitivity towards disturbance by ship and helicopter traffic; flexibility in habitat use; biogeographical population size; adult survival rate; and European threat and conservation status. Each factor was scored on a 5‐point scale from 1 (low vulnerability of seabirds) to 5 (high vulnerability of seabirds). Five of these factors could be dealt with by real data but four could only be assessed by subjective considerations based on at‐sea experience; in the latter cases, suggestions of the first author were independently modulated by experts.
Species differed greatly in their sensitivity index (SSI). Black‐throated diver Gavia arctica and red‐throated diver Gavia stellata ranked highest (= most sensitive), followed by velvet scoter Melanitta fusca , sandwich tern Sterna sandvicensis and great cormorant Phalacrocorax carbo . The lowest values were recorded for black‐legged kittiwake Rissa tridactyla , black‐headed gull Larus ridibundus and northern fulmar Fulmarus glacialis .
A WSI score for areas of the North Sea and Baltic Sea was calculated from the species‐specific sensitivity index values. Coastal waters in the south‐eastern North Sea had values indicating greater vulnerability than waters further offshore throughout the whole year.
Derived from the frequency distribution of the WSI, we suggest a ‘level of concern’ and a ‘level of major concern’ that are visualized spatially and could act as a basis for the selection of marine wind farm locations.
Synthesis and applications. The wind farm sensitivity index might be useful in strategic environmental impact assessments (EIA). Results of small‐scale EIA from wind installations should be considered within a more global perspective, provided, for example, by large mapping projects and detailed behavioural studies. This is difficult in normal EIA, particularly in highly dynamic coastal/marine habitats, and the results of this study fill an important gap by providing information on the potential sensitivity of seabirds and the importance of locations of wind installations.
The potential effects of the proposed increase in wind energy developments on birds are explored using information from studies of existing wind farms. Evidence of the four main effects, collision, displacement due to disturbance, barrier effects and habitat loss, is presented and discussed. The consequences of such effects may be direct mortality or more subtle changes to condition and breeding success. The requirements for assessing the impact of future developments are summarized, including relevant environmental legislation and appropriate methods for undertaking baseline surveys and post-construction monitoring, with particular emphasis on the rapidly developing area of offshore wind farm assessments. Mitigation measures which have the potential to minimize impacts are also summarized. Finally, recent developments in the monitoring and research of wind energy impacts on birds are outlined and some areas for future work are described.
During recent decades satellite telemetry using the Argos system has been used extensively to track many species of marine mammals. However, the aquatic behavior of most of these species results in a high number of locations with low or unknown accuracy. Argos data are often filtered to reduce the noise produced by these locations, typically by removing data points requiring unrealistic swimming speeds. Unfortunately, this method excludes a considerable number of good-quality locations that have high traveling speeds that are the result of two locations being taken very close in time. We present an alternative algorithm, based on swimming speed, distance between successive locations, and turning angles. This new filter was tested on 67 tracks from nine different marine mammal species: ringed, bearded, gray, harbor, southern elephant, and Antarctic fur seals, walruses, belugas, and narwhals. The algorithm removed similar percentages of low-quality locations (Argos location classes [LC] B and A) compared to a filter based solely on swimming speed, but preserved significantly higher percentages of good-quality positions (mean ± SE% of locations removed was 4.1 ± 0.8%vs. 12.6 ± 1.2% for LC 3; 6.8 ± 0.6%vs. 15.7 ± 0.9% for LC 2; and 11.4 ± 0.7%vs. 21.0 ± 0.9% for LC 1). The new filter was also more effective at removing unlikely, conspicuous deviations from the track's path, resulting in fewer locations being registered on land and a significant reduction in home range size, when using the Minimum Convex Polygon method, which is sensitive to outliers.
Collinearity refers to the non independence of predictor variables, usually in a regression-type analysis. It is a common feature of any descriptive ecological data set and can be a problem for parameter estimation because it inflates the variance of regression parameters and hence potentially leads to the wrong identification of relevant predictors in a statistical model. Collinearity is a severe problem when a model is trained on data from one region or time, and predicted to another with a different or unknown structure of collinearity. To demonstrate the reach of the problem of collinearity in ecology, we show how relationships among predictors differ between biomes, change over spatial scales and through time. Across disciplines, different approaches to addressing collinearity problems have been developed, ranging from clustering of predictors, threshold-based pre-selection, through latent variable methods, to shrinkage and regularisation. Using simulated data with five predictor-response relationships of increasing complexity and eight levels of collinearity we compared ways to address collinearity with standard multiple regression and machine-learning approaches. We assessed the performance of each approach by testing its impact on prediction to new data. In the extreme, we tested whether the methods were able to identify the true underlying relationship in a training dataset with strong collinearity by evaluating its performance on a test dataset without any collinearity. We found that methods specifically designed for collinearity, such as latent variable methods and tree based models, did not outperform the traditional GLM and threshold-based pre-selection. Our results highlight the value of GLM in combination with penalised methods (particularly ridge) and threshold-based pre-selection when omitted variables are considered in the final interpretation. However, all approaches tested yielded degraded predictions under change in collinearity structure and the ‘folk lore’-thresholds of correlation coefficients between predictor variables of |r| >0.7 was an appropriate indicator for when collinearity begins to severely distort model estimation and subsequent prediction. The use of ecological understanding of the system in pre-analysis variable selection and the choice of the least sensitive statistical approaches reduce the problems of collinearity, but cannot ultimately solve them.
The use of statistical models to predict the likely occurrence or distribution of species is becoming an increasingly important tool in conservation planning and wildlife management. Evaluating the predictive performance of models using independent data is a vital step in model development. Such evaluation assists in determining the suitability of a model for specific applications, facilitates comparative assessment of competing models and modelling techniques, and identifies aspects of a model most in need of improvement. The predictive performance of habitat models developed using logistic regression needs to be evaluated in terms of two components: reliability or calibration (the agreement between predicted probabilities of occurrence and observed proportions of sites occupied), and discrimination capacity (the ability of a model to correctly distinguish between occupied and unoccupied sites). Lack of reliability can be attributed to two systematic sources, calibration bias and spread. Techniques are described for evaluating both of these sources of error. The discrimination capacity of logistic regression models is often measured by cross-classifying observations and predictions in a two-by-two table, and calculating indices of classification performance. However, this approach relies on the essentially arbitrary choice of a threshold probability to determine whether or not a site is predicted to be occupied. An alternative approach is described which measures discrimination capacity in terms of the area under a relative operating characteristic (ROC) curve relating relative proportions of correctly and incorrectly classified predictions over a wide and continuous range of threshold levels. Wider application of the techniques promoted in this paper could greatly improve understanding of the usefulness, and potential limitations, of habitat models developed for use in conservation planning and wildlife management.
"A growing number of studies quantify the impact of nonlethal human disturbance on the behavior and reproductive success of animals. Athough many are well designed and analytically sophisticated, most lack a theoretical framework for making predictions and for understanding why particular responses occur. Behavioral ecologists have recently begun to fill this theoretical vacuum by applying economic models of antipredator behavior to disturbance studies. In this emerging paradigm, predation and nonlethal disturbance stimuli create similar trade-offs between avoiding perceived risk and other fitness-enhancing activities, such as feeding, parental care, or mating. A vast literature supports the hypothesis that antipredator behavior has a cost to other activities, and that this trade-off is optimized when investment in antipredator behavior tracks short-term changes in predation risk. Prey have evolved antipredator responses to generalized threatening stimuli, such as loud noises and rapidly approaching objects. Thus, when encountering disturbance stimuli ranging from the dramatic, lowflying helicopter to the quiet wildlife photographer, animal responses are likely to follow the same economic principles used by prey encountering predators. Some authors have argued that, similar to predation risk, disturbance stimuli can indirectly affect fitness and population dynamics via the energetic and lost opportunity costs of risk avoidance. We elaborate on this argument by discussing why, from an evolutionary perspective, disturbance stimuli should be analogous to predation risk. We then consider disturbance effects on the behavior of individuals--vigilance, fleeing, habitat selection, mating displays, and parental investment--as well as indirect effects on populations and communities. A wider application of predation risk theory to disturbance studies should increase the generality of predictions and make mitigation more effective without over-regulating human activities."
Marine habitats are nowadays strongly affected by human activities, while for many species the consequences of these impacts are still unclear. The red-throated diver (Gavia stellata) has been reported to be sensitive to ship traffic and other anthropogenic pressures and is consequently of high conservation concern. We studied red-throated divers in the German Bight (North Sea) using satellite telemetry and digital aerial surveys with the aim of assessing effects of ship traffic on the distribution and movements of this species during the non-breeding season. Data from the automatic identification system of ships (AIS) were intersected with bird data and allowed detailed spatial and temporal analyses. During the study period, ship traffic was present throughout the main distribution area of divers. Depending on impact radius, only small areas existed in which ship traffic was present on less than 20% of the days. Ship traffic was dominated by fishing vessels and cargo ships, but also wind farm-related ships were frequently recorded. Red-throated divers were more abundant in areas with no or little concurrent ship traffic. Analysis of aerial survey data revealed strong effects of ship speed on divers: in areas with vessels sailing at high speed only a slow resettlement of the area was observed after the disturbance, while in areas with vessels sailing at medium speed the resettlement was more rapid during the observed time period of 7 hours. Data from satellite-tracking of divers suggest that large relocation distances of individuals are related to disturbance by ships which often trigger birds to take flight. Effective measures to reduce disturbance could include channeled traffic in sensitive areas, as well as speed limits for ships traveling within the protected marine area.
Since 1979 the breeding success of c40 pairs in Hame, southern Finland has been monitored. Nests located on small islets produce more young than nests on shores. Reasons for unsuccessful nesting, including human disturbance, are considered. The red-throated diver population within the study area is on the increase. The most probable reason for this is the good breeding success, ie 1.15 offspring per pair per year.-from Authors
Seabirds select suitable habitats at sea, but these habitats may be strongly impacted by marine spatial planning, including the construction of offshore wind farms (OWFs) and the associated ship traffic. Loons (Gavia spp.) are particularly vulnerable to anthropogenic activities and are also of high conservation status, making them particularly relevant to marine planning processes. We investigated the effects of OWF construction and ship traffic on Loon distributions in the German North Sea on a large spatial scale, using a 'before-after' control impact analysis approach and a long-term data set. Many OWFs were built in or close to core areas of Loon distributions. Loons showed significant shifts in their distribution in the 'after' period and subsequently aggregated between two OWF clusters, indicating the remaining suitable habitat. The decrease in Loon abundance became significant as far as about 16 km from the closest OWF. Ship traffic also had a significant negative impact on Loons, indicating that OWFs deterred Loons through the combined effect of ship traffic and the wind turbines themselves. This study provides the first analysis of the extensive effects of OWFs and ships on Loons on a large spatial scale. The results provide an essential baseline for future marine spatial planning processes in the German North Sea and elsewhere.
Red-throated Loon (Gavia stellata) numbers in Alaska have fluctuated dramatically over the past 3 decades; however, the demographic processes contributing to these population dynamics are poorly understood. To examine spatial and temporal variation in productivity, we estimated breeding parameters at 5 sites in Alaska: at Cape Espenberg and the Copper River Delta we estimated nest survival, and at 3 sites within the Yukon-Kuskokwim Delta we estimated nest survival and productivity. Nest survival varied broadly among sites and years; annual estimates (lower, upper 95% confidence interval) ranged from 0.09 (0.03, 0.29) at Cape Espenberg in 2001 to 0.93 (0.76, 0.99) at the Copper River Delta in 2002. Annual variation among sites was not concordant, suggesting that site-scale factors had a strong influence on nest survival. Models of nest survival indicated that visits to monitor nests had a negative effect on nest daily survival probability, which if not accounted for biased nest survival strongly downward. The sensitivity of breeding Red-throated Loons to nest monitoring suggests other sources of disturbance that cause incubating birds to flush from their nests may also reduce nest survival. Nest daily survival probability at the Yukon-Kuskokwim Delta was negatively associated with an annual index of fox occurrence. Survival through the incubation and chick-rearing periods on the Yukon-Kuskokwim Delta ranged from 0.09 (0.001, 0.493) to 0.50 (0.04, 0.77). Daily survival probability during the chick-rearing period was lower for chicks that had a sibling in 2 of 3 years, consistent with the hypothesis that food availability was limited. Estimates of annual productivity on the Yukon-Kuskokwim Delta ranged from 0.17 to 1.0 chicks per pair. Productivity was not sufficient to maintain population stability in 2 of 3 years, indicating that nest depredation by foxes and poor foraging conditions during chick rearing can have important effects on productivity.
Anthropogenic developments in marine coastal zones potentially overlap with areas of conservation interest, including important areas for birds. Ideally, spatial patterns of species abundance should be considered at ecologically relevant spatial resolutions (high resolutions) to inform spatial planning and environmental assessments. Most planning so far, however, has relied on coarse-resolution distribution maps from atlas projects or models often based on limited datasets (few surveys), and relationships with environmental variables have rarely been taken into account, leaving many studies and recommendations vulnerable to criticism. We therefore combined the strengths of a detailed database of spatially explicit aerial and ship surveys with high-resolution environmental predictors and species distribution models to predict detailed density patterns for 3 sea duck species, as part of an environmental impact assessment (EIA) in the southern Baltic Sea. We also compared the results from 2 differen...
Summary. Recent work by Reiss and Ogden provides a theoretical basis for sometimes preferring restricted maximum likelihood (REML) to generalized cross-validation (GCV) for smoothing parameter selection in semiparametric regression. However, existing REML or marginal likelihood (ML) based methods for semiparametric generalized linear models (GLMs) use iterative REML or ML estimation of the smoothing parameters of working linear approximations to the GLM. Such indirect schemes need not converge and fail to do so in a non-negligible proportion of practical analyses. By contrast, very reliable prediction error criteria smoothing parameter selection methods are available, based on direct optimization of GCV, or related criteria, for the GLM itself. Since such methods directly optimize properly defined functions of the smoothing parameters, they have much more reliable convergence properties. The paper develops the first such method for REML or ML estimation of smoothing parameters. A Laplace approximation is used to obtain an approximate REML or ML for any GLM, which is suitable for efficient direct optimization. This REML or ML criterion requires that Newton–Raphson iteration, rather than Fisher scoring, be used for GLM fitting, and a computationally stable approach to this is proposed. The REML or ML criterion itself is optimized by a Newton method, with the derivatives required obtained by a mixture of implicit differentiation and direct methods. The method will cope with numerical rank deficiency in the fitted model and in fact provides a slight improvement in numerical robustness on the earlier method of Wood for prediction error criteria based smoothness selection. Simulation results suggest that the new REML and ML methods offer some improvement in mean-square error performance relative to GCV or Akaike's information criterion in most cases, without the small number of severe undersmoothing failures to which Akaike's information criterion and GCV are prone. This is achieved at the same computational cost as GCV or Akaike's information criterion. The new approach also eliminates the convergence failures of previous REML- or ML-based approaches for penalized GLMs and usually has lower computational cost than these alternatives. Example applications are presented in adaptive smoothing, scalar on function regression and generalized additive model selection.
At present, all studies on the impact of offshore windfarms on pelagic fish are restricted to a narrow survey area of a localised windfarm and surrounding reference areas. The same applies for investigations at the alpha ventus offshore windfarm. These include surveys on the distribution of pelagic fish in alpha ventus and the surrounding area based on hydroacoustic measurements, addressing immediate attraction and repulsion effects of offshore windfarms. The effect of changes in food supply was addressed as a single effect by analysis of the gut content of pelagic fish in and outside alpha ventus. The study was performed over the period from August 2008 to April 2012. The survey covers a period before construction, during construction and during operation of the windfarm, in different seasons (spring, summer and autumn). The study further includes an evaluation of the survey methods, including development of a stationary measuring system for hydroacoustic long-term monitoring of fish.
Many established models of animal foraging assume that individuals are ecologically equivalent. However, it is increasingly recognized that populations may comprise individuals who differ consistently in their diets and foraging behaviors. For example, recent studies have shown that individual foraging site fidelity (IFSF, when individuals consistently forage in only a small part of their population's home range) occurs in some colonial breeders. Short-term IFSF could result from animals using a win-stay, lose-shift foraging strategy. Alternatively, it may be a consequence of individual specialization. Pelagic seabirds are colonial central-place foragers, classically assumed to use flexible foraging strategies to target widely dispersed, spatiotemporally patchy prey. However, tracking has shown that IFSF occurs in many seabirds, although it is not known whether this persists across years. To test for long-term IFSF and to examine alternative hypotheses concerning its cause, we repeatedly tracked 55 Northern Gannets (Morus bassanus) from a large colony in the North Sea within and across three successive breeding seasons. Gannets foraged in neritic waters, predictably structured by tidal mixing and thermal stratification, but subject to stochastic, wind-induced overturning. Both within and across years, coarse to mesoscale (tens of kilometers) IFSF was significant but not absolute, and foraging birds departed the colony in individually consistent directions. Carbon stable isotope ratios in gannet blood tissues were repeatable within years and nitrogen ratios were also repeatable across years, suggesting long-term individual dietary specialization. Individuals were also consistent across years in habitat use with respect to relative sea surface temperature and in some dive metrics, yet none of these factors accounted for IFSF. Moreover, at the scale of weeks, IFSF did not decay over time and the magnitude of IFSF across years was similar to that within years, suggesting that IFSF is not primarily the result of win-stay, lose-shift foraging. Rather, we hypothesize that site familiarity, accrued early in life, causes IFSF by canalizing subsequent foraging decisions. Evidence from this and other studies suggests that IFSF may be common in colonial central-place foragers, with farreaching consequences for our attempts to understand and conserve these animals in a rapidly changing environment.
The construction and operation of wind-power plants may affect birds through collision mortality,
reduced habitat utilization due to disturbance, barriers to movement and habitat modifications, with
the nature and magnitude of those effects being site- and species-specific. Birds may however manage
these effects through fleeing, activity shifts or changed habitat utilization; usually termed avoidance.
Given the important role avoidance plays in estimating the impact wind-power development has on
birds, there is a pressing need to formalizing the avoidance process. Crucial in this context is to identify
the underlying mechanisms of behavioural responses by birds to wind-power plants and individual turbines.
To provide a better basis for and improved understanding of the underlying mechanisms for avoidance
a conceptual framework for wind-turbine avoidance is presented decomposing various forms of
avoidance at different spatial scales. Avoidance behaviour includes displacement (macro-avoidance),
anticipatory and impulsive evasion (meso-avoidance), and escape (micro-avoidance). For understanding
why particular responses occur with regard to wind-turbine disturbance this concept is applied to predation
risk theory. The risk-disturbance hypothesis elucidates possible trade-offs between avoiding perceived
risk and fitness-enhancing activities. The four behavioural responses are related to, respectively,
habitat selection, vigilance and fleeing (twice); from which specific predictions can be derived.
Formalizing the different forms of avoidance facilitates design of effects studies, enhances comparisons
among sites studied, and guide siting and mitigation strategies.
We captured 575 Xantus' Murrelets (Synthliboramphus hypoleucus) with spotlights and dip nets at 3 islands in the Southern California Channel Islands during April and May of 1995-1997. Working at night (2100-0500 h), 3-person teams in inflatable boats located murrelets with a spotlight and captured them in dip nets from the waters near known breeding colonies at Santa Barbara, Anacapa, and San Clemente Islands. Our average capture rate was 4.7 murrelets hr-1, but we captured up to 12.3 murrelets hr-1. We recaptured 34 murrelets or 6% of the capture total. We recommend this simple, inexpensive, safe and effective night-lighting capture technique for Xantus' Murrelets and other seabirds.
Today, increasing use intensity and establishment of new sea uses such as offshore wind farming can be observed in coastal and marine waters. This development also increases the pressure on coastal and marine ecosystems. The exclusive economic zone of the German North Sea can serve as an example for this development, in particular illustrating the need to combine multiple uses and societal demands within a given sea area. In order to deal with the resulting conflicts and cumulative impacts, new planning tools and integrated approaches to planning and management are developing. While the sea becomes a contested but at the same time politically recognised area, also conflicts rooted in different perceptions, values and attitudes of coastal people can be observed. In order to deal with the current challenges in marine areas, marine spatial planning and similar tools for integrated planning need to be developed in the form of communication processes, which link diverse sets of information and span a dialogue between groups of society and across spatial scales including the transnational dimension.
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.
Red-throated divers are piscivorous seabirds considered to be opportunistic feeders. The overall knowledge about their diet at sea is scarce. A large sample size of 82 by-caught red-throated divers from two winter (2001–02 and 2002–03) and three spring periods (2003, 2004 and 2005) offered the unique opportunity to analyse their dietary composition in the Pomeranian Bight. This area represents a hot spot in their winter distribution in the southwestern Baltic Sea and a marine protected area has been established due to its importance for the divers and other seabird species. Diet composition was analysed based on stomach and gut contents. The comparison of the different prey species was mainly based on reconstructed biomass using regressions between skeletal hard parts such as otoliths and original fish length and weight. The diet of the divers comprised eleven different fish species and nine different families. No interannual differences in the consumption of the nine most important prey species could be observed. However, in contrast to the other fish species the consumption of Atlantic herring and zander differed significantly between seasons. Herring supplied the majority of prey biomass in all three spring periods and zander in both winter periods. Moreover, the average length of herring consumed differed significantly between seasons. In winter, smaller herring was consumed compared to spring. The distinct seasonal changes in the diet composition were paralleled and most probably evoked by the migration pattern of the Western Baltic spring spawning herring which has its main spawning grounds adjacent to the study area. Based on the habitat requirements of the different prey species it could be inferred that mostly the coastal waters of the bight were used for foraging. Its function as spawning, nursery area and feeding ground with numerous resident and migrating fish species available might explain the important role of the Pomeranian Bight as wintering and staging area for red-throated divers in the southwestern Baltic Sea.
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.