Seabirds have increasingly encountered offshore wind farms (OWFs) in European waters in the past ... more Seabirds have increasingly encountered offshore wind farms (OWFs) in European waters in the past 10 years, resulting in potential conflicts with offshore foraging areas. During the breeding season, seabirds are restricted in their choice of foraging habitat and are under increased pressure to find enough prey to raise their offspring. However, information on the individual reactions of seabirds towards OWFs during the breeding season is lacking. Three OWFs located 23-35 km north of the island of Helgoland have operated since October 2015. We studied their possible effects on locally breeding common guillemots (Uria aalge) using GPS tracking. GPS tags were deployed on 12 breeding guillemots from Helgoland for 8-26 days during 2016-2017. Most individuals avoided the OWFs, but one individual in each year briefly entered the OWFs on two or three occasions. Using a point process model, we revealed a 63% reduction in the resource selection of the OWF areas compared with the surroundings (lower confidence interval (CI) = 79% reduction, upper CI = 36% reduction). Furthermore, OWF avoidance was increased to 75% when the turbine blades were rotating (lower CI = 93% reduction, upper CI = 11% reduction). Guillemots mainly approached the OWFs from their eastern edge when resting or diving, and rarely approached the areas when commuting. These results provide a detailed description of guillemot reactions to OWFs during the breeding season, and the first comprehensive analysis of OWF effects on this species based on telemetry data. The strong avoidance effect for guillemots during the breeding season indicates the need to consider the presence of OWFs when interpreting future trends in the abundance and breeding success of this species.
Background: New wildlife telemetry and tracking technologies have become available in the last de... more Background: New wildlife telemetry and tracking technologies have become available in the last decade, leading to a large increase in the volume and resolution of animal tracking data. These technical developments have been accompanied by various statistical tools aimed at analysing the data obtained by these methods. Methods: We used simulated habitat and tracking data to compare some of the different statistical methods frequently used to infer local resource selection and large-scale attraction/avoidance from tracking data. Notably, we compared spatial logistic regression models (SLRMs), spatio-temporal point process models (ST-PPMs), step selection models (SSMs), and integrated step selection models (iSSMs) and their interplay with habitat and animal movement properties in terms of statistical hypothesis testing. Results: We demonstrated that only iSSMs and ST-PPMs showed nominal type I error rates in all studied cases, whereas SSMs may slightly and SLRMs may frequently and strongly exceed these levels. iSSMs appeared to have on average a more robust and higher statistical power than ST-PPMs. Conclusions: Based on our results, we recommend the use of iSSMs to infer habitat selection or large-scale attraction/avoidance from animal tracking data. Further advantages over other approaches include short computation times, predictive capacity, and the possibility of deriving mechanistic movement models.
Background: Departure decisions in long-distance migratory bird species may depend on favourable ... more Background: Departure decisions in long-distance migratory bird species may depend on favourable weather conditions and bene cial resources at the destination location, overarched by genetic triggers. However, few studies have tried to validate the signi cance of these three concepts simultaneously, and long-term, high-resolution tagging datasets recording individual movements across consecutive years are scarce. We used such a dataset to explore intraspeci c and intra-individual variabilities in departure and arrival decisions from/to wintering grounds in relation to these three different concepts in bird migration. Methods: We equipped 23 curlews (Numenius arquata) wintering in the Wadden Sea with Global Positioning System data loggers to record their spatio-temporal patterns of departure from and arrival at their wintering site, and the rst part of their migration. We obtained data for 42 migrations over 6 years, with 12 individuals performing repeat migrations in consecutive years. Departure and arrival dates were related to 73 meteorological and bird-related predictors using the least absolute shrinkage and selection operator (LASSO) to identify drivers of departure and arrival decisions. Results: Curlews migrated almost exclusively to Arctic and sub-Arctic Russia for breeding. They left their wintering site mainly during the evening from mid-to late April and returned between the end of June and mid-July. There was no difference in departure times between the sexes. Weather parameters did not impact departure decisions; if departure days coincided with headwind conditions, the birds accounted for this by ying at higher altitudes of up to several kilometres. Curlews breeding further away in areas with late snowmelt departed later. Departures dates varied by only <4 days in individual curlews tagged over consecutive years. Conclusions: These results suggest that the trigger for migration in a long-distance migrant is largely independent of weather conditions but is subject to resource availability in breeding areas. The high intraindividual repeatability of departure days among subsequent years and the lack of relationship to weather parameters suggest the importance of genetic triggers in prompting the start of migration. Further insights into the timing of migration in immatures and closely related birds might help to further unravel the genetic mechanisms triggering migration patterns.
This article has been accepted for publication and undergone full peer review but has not been th... more This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as
The South Pacific Gyre has the most hyper-oligotrophic waters in the world and is considered the ... more The South Pacific Gyre has the most hyper-oligotrophic waters in the world and is considered the largest "oceanic desert." Rapa Nui (Easter Island), located within the South Pacific Gyre, is a breeding ground for masked boobies (Sula dactylatra), which are seabirds with a foraging range that effectively confines them within the gyre. The foraging ecology of this species in the gyre was examined by attaching GPS and time-depth devices to chick-rearing adult birds (9 and 14 birds in 2016 and 2017, respectively) and by collecting regurgitates (18 and 15 samples in 2016 and 2017, respectively). In addition, the birds' foraging ecology between years was compared. Masked boobies traveled in various directions, dived at unspecific locations, and explored areas < 110 km from the colony. Local environmental conditions were not significantly different between years, and differences in foraging parameters (maximum foraging range, trip duration, and dive depth) were greater among individuals than between years. The foraging characteristics of masked boobies suggest that resources were ephemerally distributed around the colony, with similar abundances across years. Under these conditions, traveling to unspecific locations may increase the area covered and the probability of prey encounter. The spatial and temporal consistencies in environmental conditions explain the uniformity of foraging parameters between years. The ability of masked boobies to exploit ephemerally distributed resources in seascapes like Rapa Nui may help explain its pantropical distribution.
Top predators such as coastal birds are essential components of marine food webs, and understandi... more Top predators such as coastal birds are essential components of marine food webs, and understanding their trophic interactions forms an essential basis of food web models. At the same time, the proportion of plastic debris in marine food webs has constantly increased while the degree of plastic ingestion by marine birds is still poorly known. In this study, the diets and microplastic uptakes in two numerous benthivorous bird species in the Wadden Sea were examined microscopically, i.e. the common eider (Sommateria mollissima) indicative for the subtidal and the common shelduck (Tadorna tadorna) indicative for the intertidal area. Eiders (n = 42 carcasses; n = 120 faecal samples) mainly ingested common cockles (Cerastoderma edule). Blue mussels (Mytilus edulis) ranged second and-same as the invasive razor clam (Ensis leei)-occurred more frequently than reflected by historic data. Proportions of gastropods, bristle worms and crustaceans were low. Shelducks (n = 20 carcasses; n = 98 faecal samples) fed mainly on small molluscs, especially C. edule, mud snails Peringia ulvae, and amphipods. Plastic debris was found in 92.9% of the stomachs and 74.2% of the faeces from eiders as well as in 95% of the stomachs and 85.7% of the faeces from shelducks. Filaments in shelduck prey remains were significantly larger, whereas there was no species-specific difference in abundance of filaments. Most plastic consisted of brightly coloured filaments ˂ 5 mm. These findings indicate regular uptake and excretion of plastic debris by coastal benthivorous seabirds, both in the subtidal and intertidal realm. The origin and mode of uptake of microplastics are discussed.
European Journal of Wildlife Research, Apr 28, 2021
Wetlands such as the World Heritage Site in the Wadden Sea include important habitats for breedin... more Wetlands such as the World Heritage Site in the Wadden Sea include important habitats for breeding waterbirds. Its saltmarshes and adjacent conservation polders are used by thousands of breeding birds. However, some alarming population declines have been recorded during recent decades and previous studies found indications that predation pressure from red foxes (Vulpes vulpes) and more recently from invasive racoon dogs (Nyctereutes procyonoides) played an important role. The current study aimed to assess habitat utilisation by foxes and racoon dogs along the coast of the Wadden Sea. We equipped 21 foxes and seven racoon dogs with GPS collars and recorded a total of 37,586 (mean: 2,088) GPS fixes during a total of 2,617 (mean: 145) equipment days for red foxes and 3,440 (mean: 573) GPS fixes during a total of 272 (mean: 45) equipment days for racoon dogs. Foxes showed high individual variability in Kernel 95% home range sizes, with a mean of 172.2 ha (range: 3 to 824 ha) and little overlap among territories. Males had significantly larger home ranges than females, and there were no differences in home range sizes between adults (n = 14) and young (n = 4). Racoon dogs had smaller home ranges than foxes (mean: 52.8 ha). The preferred habitat type of both predators during daytime was the conservation polders along the Wadden Sea, while foxes also selected saltmarshes during the night. In contrast, both species avoided farmland areas. Foxes showed 20% of their activity during daylight hours and spent this time largely in areas with dense vegetation cover. None of the tagged individuals entered areas with particularly high bird densities (i.e. Wadden Sea islands or Halligen). However, our data suggest that foxes and racoon dogs frequently make use of linear structures such as dykes and dams and patrol along the tide line for carcasses. This suggests that at least single individuals of both species are prone to enter islands that are connected by dams to the mainland.
Experimental studies have shown that individual wildfowl can shorten or skip moulting if the time... more Experimental studies have shown that individual wildfowl can shorten or skip moulting if the time between breeding and wintering is short; however, studies in wild birds are scarce. We tracked nine Common Shelducks Tadorna tadorna during the breeding and moulting seasons and determined the flightless time during moulting based on typical movement patterns. We found different movement patterns for two late-breeding females, suggesting that they skipped or shortened the moult of their flight feathers. These results provide a link between previous experimental studies and the situation in wild birds, likely reflecting an individual trade-off between the times allocated to moulting and breeding, respectively. Keywords Tadorna tadorna • Flight feathers • Annual cycle • Wildfowl • Breeding season • Water bird Zusammenfassung Ungewöhnliches Muster einer übersprungenen oder verkürzten Mauser des Fluggefieders bei spät brütenden Brandgänsen Experimentelle Studien haben gezeigt, dass die Mauser bei einzelnen Entenvögeln verkürzt oder übersprungen werden kann, wenn nur wenig Zeit zwischen der Brutzeit und dem Winter liegt. Studien an wildlebenden Vögeln sind jedoch selten. Wir haben neun Brandgänse Tadorna tadorna während der Brut-und Mauserzeit mit Satellitensendern verfolgt und ihre flugunfähige Zeit während der Mauser anhand typischer Bewegungsmuster für diesen Zeitraum bestimmt. Bei zwei spät brütenden Weibchen fanden wir ungewöhnliche Bewegungsmuster, die vermuten lassen, dass sie die Mauser des Fluggefieders übersprungen oder verkürzt haben. Diese Ergebnisse liefern eine Verbindung zwischen früheren experimentellen Studien und wildlebenden Vögeln. Wahrscheinlich spiegeln sie eine notwendige Abwägung zwischen der Zeit wider, welche individuelle Vögel für die Mauser und die Brutzeit zur Verfügung haben.
Understanding fishery impacts is imperative for understanding marine ecology and conservation. Th... more Understanding fishery impacts is imperative for understanding marine ecology and conservation. The global marine fishing industry currently dumps ~10 million tonnes (10%) of their annual catch (Zeller, Cashion, Palomares, & Pauly, 2018), yet discarding is probably one of the least studied component of fishery impacts. Discarding peaked at 18.9 million tonnes in 1989, but has since almost halved (Zeller et al., 2018), and changes in policy, such as discard bans in the European Union (EU Landing Obligation), Norway, Chile and New Zealand, are likely to reduce discarding further (Real et al., 2018). Although bans are desirable for stock management, they may have unforeseen knock-on effects for the mammals, seabirds, fishes and crustaceans that scavenge on discharged biomass (Bicknell, Oro,
Recommendations for project-related studies of possible impacts of marine wind farms during const... more Recommendations for project-related studies of possible impacts of marine wind farms during construction and operation on birds The construction of offshore windfarms may become the largest technical impact on Europe's marine habitats. For roughly a quarter of the area of Germany's Exclusive Economic Zone there are plans to erect offshore windfarms. Several international conventions as well as national laws necessitate environmental impact assessment studies. We hence suggest methods for standardised investigations on the distribution, movements and flight behaviour of birds at sea. They include visual, acoustic and radar-based techniques and observations.
Wetlands such as the World Heritage Site in the Wadden Sea include important habitats for breedin... more Wetlands such as the World Heritage Site in the Wadden Sea include important habitats for breeding waterbirds. Its saltmarshes and adjacent conservation polders are used by thousands of breeding birds. However, some alarming population declines have been recorded during recent decades and previous studies found indications that predation pressure from red foxes (Vulpes vulpes) and more recently from invasive racoon dogs (Nyctereutes procyonoides) played an important role. The current study aimed to assess habitat utilisation by foxes and racoon dogs along the coast of the Wadden Sea. We equipped 21 foxes and seven racoon dogs with GPS collars and recorded a total of 37,586 (mean: 2,088) GPS fixes during a total of 2,617 (mean: 145) equipment days for red foxes and 3,440 (mean: 573) GPS fixes during a total of 272 (mean: 45) equipment days for racoon dogs. Foxes showed high individual variability in Kernel 95% home range sizes, with a mean of 172.2 ha (range: 3 to 824 ha) and little ...
Migration patterns in birds vary in space and time. Spatial patterns include chain, leapfrog and ... more Migration patterns in birds vary in space and time. Spatial patterns include chain, leapfrog and telescopic migration. Temporal patterns such as migration duration, number, and duration of stopovers may vary according to breeding latitude, sex, and season. This study aimed to verify these patterns in a long‐distance migrant, the Eurasian curlew Numenius arquata arquata, and to provide a synopsis of spatio‐temporal migration patterns in this species of concern throughout the East Atlantic Flyway. We tagged 85 adults with GPS‐data loggers in Germany, Poland, France and Estonia between 2013 and 2019. We computed the distance flown, linear loxodromic distance, duration, stopover number, total stopover duration, mean stopover duration, departure time and arrival time for 177 out of 187 tracks. On average (± standard deviation), spring migration occurred from 4 to 14 April (10.2 ± 8.4 days), curlews flew 3.623 ± 1.366 km, and had 5.8 ± 3.6 stopovers, with a duration of 29.4 ± 38.2 h per s...
The Wadden Sea is one of the most important foraging areas for breeding and migrating birds. Howe... more The Wadden Sea is one of the most important foraging areas for breeding and migrating birds. However, little is known about the preferred feeding places of birds and how the intense predation pressure influences the food web. Within the project STopP the trophodynamic structure of different Wadden Sea habitats is determined to get an idea how sediment characteristics and hydrodynamics modify habitats that serve as food sources for birds.
The Wadden Sea is one of the most important stop-over sites for 10 to 12 Million migrating birds ... more The Wadden Sea is one of the most important stop-over sites for 10 to 12 Million migrating birds per year. But little is known about the influence of birds on the entire ecosystem. We conducted Ecological Network Analysis (ENA) in an important resting site in the Wadden Sea to determine the influence of birds on the food web. A large variety of different bird species uses the area for foraging and is included directly or indirectly in most of the pathways. Birds induce a negative impact on their prey items with a positive feedback reaction to the preys’ competitors and food sources. There is also a strong negative impact among the bird compartments probably due to competition between the birds. Changes in the biomass of the birds revealed alterations in the food web structure. With a decline in the avian biomass the system showed a decrease in connectivity and diversity of flows but an increase in recycling. Changes in the bird population could affect the complexity and functioning ...
can be learned about seabird foraging behavior through biologging. I guess the lack of a broader ... more can be learned about seabird foraging behavior through biologging. I guess the lack of a broader context and clear aims is related to the fact that the manuscript forms part of a special issue, and that the authors are trying to show how seabirds can play a part in an ocean observation network. However, in my opinion the manuscript should also be accessible and interesting to readers who’re unfamiliar with COSYNA, and this will require a bit more context, more clearly defined aims, and a discussion of the pros and cons of the chosen approach in terms of reaching those aims.
Background: New wildlife telemetry and tracking technologies have become available in the last de... more Background: New wildlife telemetry and tracking technologies have become available in the last decade, leading to a large increase in the volume and resolution of animal tracking data. These technical developments have been accompanied by various statistical tools aimed at analysing the data obtained by these methods. Methods: We used simulated habitat and tracking data to compare some of the different statistical methods frequently used to infer local resource selection and large-scale attraction/avoidance from tracking data. Notably, we compared the performances of spatial logistic regression models (SLRMs), point process models (PPMs), and integrated step selection models ((i)SSMs) and their interplays with habitat, tracking-device, and animal movement properties. Results: We demonstrated that SLRMs were inappropriate for large-scale attraction studies and prone to bias when inferring habitat selection. In contrast, PPMs and (i)SSMs showed comparable (unbiased) performances for b...
Northern gannets (Morus bassanus) have been ranked as one of the most vulnerable species in terms... more Northern gannets (Morus bassanus) have been ranked as one of the most vulnerable species in terms of collision with offshore wind farm (OWF) turbines, and strong avoidance of OWFs has been documented for this species. Gannets increasingly encounter OWFs within the ranges of their largest breeding colonies along the European coasts. However, information on their actual reactions to OWFs during the breeding season is lacking. We investigated the possible effects of OWFs located 23-35 km north of the colony on Helgoland in the southern North Sea on breeding gannets. GPS tags were applied to 28 adult gannets breeding on Helgoland for several weeks over 2 years. Most gannets (89%) predominantly avoided the OWFs in both years, but 11% frequently entered them when foraging or commuting between the colony and foraging areas. Flight heights inside the OWFs were close to the rotor-blade zone, especially for individuals predominantly avoiding the OWFs. Gannets preferred distances of 250-450 m to the turbines when being inside the OWF. A point process modelling approach revealed that the gannets resource selection of the OWF area compared with the surroundings (outside OWF = up to 15 km from the OWF border) was reduced by 21% in 2015 and 37% in 2016. This study provides the first detailed characterisation of individual reactions of gannets to OWFs during the breeding season and one of the first comprehensive studies of OWF effects on this species based on telemetry data. The documented effects need to be considered during the planning processes for future OWFs, especially those located close to large seabird breeding colonies.
Seabirds have increasingly encountered offshore wind farms (OWFs) in European waters in the past ... more Seabirds have increasingly encountered offshore wind farms (OWFs) in European waters in the past 10 years, resulting in potential conflicts with offshore foraging areas. During the breeding season, seabirds are restricted in their choice of foraging habitat and are under increased pressure to find enough prey to raise their offspring. However, information on the individual reactions of seabirds towards OWFs during the breeding season is lacking. Three OWFs located 23-35 km north of the island of Helgoland have operated since October 2015. We studied their possible effects on locally breeding common guillemots (Uria aalge) using GPS tracking. GPS tags were deployed on 12 breeding guillemots from Helgoland for 8-26 days during 2016-2017. Most individuals avoided the OWFs, but one individual in each year briefly entered the OWFs on two or three occasions. Using a point process model, we revealed a 63% reduction in the resource selection of the OWF areas compared with the surroundings (lower confidence interval (CI) = 79% reduction, upper CI = 36% reduction). Furthermore, OWF avoidance was increased to 75% when the turbine blades were rotating (lower CI = 93% reduction, upper CI = 11% reduction). Guillemots mainly approached the OWFs from their eastern edge when resting or diving, and rarely approached the areas when commuting. These results provide a detailed description of guillemot reactions to OWFs during the breeding season, and the first comprehensive analysis of OWF effects on this species based on telemetry data. The strong avoidance effect for guillemots during the breeding season indicates the need to consider the presence of OWFs when interpreting future trends in the abundance and breeding success of this species.
Background: New wildlife telemetry and tracking technologies have become available in the last de... more Background: New wildlife telemetry and tracking technologies have become available in the last decade, leading to a large increase in the volume and resolution of animal tracking data. These technical developments have been accompanied by various statistical tools aimed at analysing the data obtained by these methods. Methods: We used simulated habitat and tracking data to compare some of the different statistical methods frequently used to infer local resource selection and large-scale attraction/avoidance from tracking data. Notably, we compared spatial logistic regression models (SLRMs), spatio-temporal point process models (ST-PPMs), step selection models (SSMs), and integrated step selection models (iSSMs) and their interplay with habitat and animal movement properties in terms of statistical hypothesis testing. Results: We demonstrated that only iSSMs and ST-PPMs showed nominal type I error rates in all studied cases, whereas SSMs may slightly and SLRMs may frequently and strongly exceed these levels. iSSMs appeared to have on average a more robust and higher statistical power than ST-PPMs. Conclusions: Based on our results, we recommend the use of iSSMs to infer habitat selection or large-scale attraction/avoidance from animal tracking data. Further advantages over other approaches include short computation times, predictive capacity, and the possibility of deriving mechanistic movement models.
Background: Departure decisions in long-distance migratory bird species may depend on favourable ... more Background: Departure decisions in long-distance migratory bird species may depend on favourable weather conditions and bene cial resources at the destination location, overarched by genetic triggers. However, few studies have tried to validate the signi cance of these three concepts simultaneously, and long-term, high-resolution tagging datasets recording individual movements across consecutive years are scarce. We used such a dataset to explore intraspeci c and intra-individual variabilities in departure and arrival decisions from/to wintering grounds in relation to these three different concepts in bird migration. Methods: We equipped 23 curlews (Numenius arquata) wintering in the Wadden Sea with Global Positioning System data loggers to record their spatio-temporal patterns of departure from and arrival at their wintering site, and the rst part of their migration. We obtained data for 42 migrations over 6 years, with 12 individuals performing repeat migrations in consecutive years. Departure and arrival dates were related to 73 meteorological and bird-related predictors using the least absolute shrinkage and selection operator (LASSO) to identify drivers of departure and arrival decisions. Results: Curlews migrated almost exclusively to Arctic and sub-Arctic Russia for breeding. They left their wintering site mainly during the evening from mid-to late April and returned between the end of June and mid-July. There was no difference in departure times between the sexes. Weather parameters did not impact departure decisions; if departure days coincided with headwind conditions, the birds accounted for this by ying at higher altitudes of up to several kilometres. Curlews breeding further away in areas with late snowmelt departed later. Departures dates varied by only <4 days in individual curlews tagged over consecutive years. Conclusions: These results suggest that the trigger for migration in a long-distance migrant is largely independent of weather conditions but is subject to resource availability in breeding areas. The high intraindividual repeatability of departure days among subsequent years and the lack of relationship to weather parameters suggest the importance of genetic triggers in prompting the start of migration. Further insights into the timing of migration in immatures and closely related birds might help to further unravel the genetic mechanisms triggering migration patterns.
This article has been accepted for publication and undergone full peer review but has not been th... more This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as
The South Pacific Gyre has the most hyper-oligotrophic waters in the world and is considered the ... more The South Pacific Gyre has the most hyper-oligotrophic waters in the world and is considered the largest "oceanic desert." Rapa Nui (Easter Island), located within the South Pacific Gyre, is a breeding ground for masked boobies (Sula dactylatra), which are seabirds with a foraging range that effectively confines them within the gyre. The foraging ecology of this species in the gyre was examined by attaching GPS and time-depth devices to chick-rearing adult birds (9 and 14 birds in 2016 and 2017, respectively) and by collecting regurgitates (18 and 15 samples in 2016 and 2017, respectively). In addition, the birds' foraging ecology between years was compared. Masked boobies traveled in various directions, dived at unspecific locations, and explored areas < 110 km from the colony. Local environmental conditions were not significantly different between years, and differences in foraging parameters (maximum foraging range, trip duration, and dive depth) were greater among individuals than between years. The foraging characteristics of masked boobies suggest that resources were ephemerally distributed around the colony, with similar abundances across years. Under these conditions, traveling to unspecific locations may increase the area covered and the probability of prey encounter. The spatial and temporal consistencies in environmental conditions explain the uniformity of foraging parameters between years. The ability of masked boobies to exploit ephemerally distributed resources in seascapes like Rapa Nui may help explain its pantropical distribution.
Top predators such as coastal birds are essential components of marine food webs, and understandi... more Top predators such as coastal birds are essential components of marine food webs, and understanding their trophic interactions forms an essential basis of food web models. At the same time, the proportion of plastic debris in marine food webs has constantly increased while the degree of plastic ingestion by marine birds is still poorly known. In this study, the diets and microplastic uptakes in two numerous benthivorous bird species in the Wadden Sea were examined microscopically, i.e. the common eider (Sommateria mollissima) indicative for the subtidal and the common shelduck (Tadorna tadorna) indicative for the intertidal area. Eiders (n = 42 carcasses; n = 120 faecal samples) mainly ingested common cockles (Cerastoderma edule). Blue mussels (Mytilus edulis) ranged second and-same as the invasive razor clam (Ensis leei)-occurred more frequently than reflected by historic data. Proportions of gastropods, bristle worms and crustaceans were low. Shelducks (n = 20 carcasses; n = 98 faecal samples) fed mainly on small molluscs, especially C. edule, mud snails Peringia ulvae, and amphipods. Plastic debris was found in 92.9% of the stomachs and 74.2% of the faeces from eiders as well as in 95% of the stomachs and 85.7% of the faeces from shelducks. Filaments in shelduck prey remains were significantly larger, whereas there was no species-specific difference in abundance of filaments. Most plastic consisted of brightly coloured filaments ˂ 5 mm. These findings indicate regular uptake and excretion of plastic debris by coastal benthivorous seabirds, both in the subtidal and intertidal realm. The origin and mode of uptake of microplastics are discussed.
European Journal of Wildlife Research, Apr 28, 2021
Wetlands such as the World Heritage Site in the Wadden Sea include important habitats for breedin... more Wetlands such as the World Heritage Site in the Wadden Sea include important habitats for breeding waterbirds. Its saltmarshes and adjacent conservation polders are used by thousands of breeding birds. However, some alarming population declines have been recorded during recent decades and previous studies found indications that predation pressure from red foxes (Vulpes vulpes) and more recently from invasive racoon dogs (Nyctereutes procyonoides) played an important role. The current study aimed to assess habitat utilisation by foxes and racoon dogs along the coast of the Wadden Sea. We equipped 21 foxes and seven racoon dogs with GPS collars and recorded a total of 37,586 (mean: 2,088) GPS fixes during a total of 2,617 (mean: 145) equipment days for red foxes and 3,440 (mean: 573) GPS fixes during a total of 272 (mean: 45) equipment days for racoon dogs. Foxes showed high individual variability in Kernel 95% home range sizes, with a mean of 172.2 ha (range: 3 to 824 ha) and little overlap among territories. Males had significantly larger home ranges than females, and there were no differences in home range sizes between adults (n = 14) and young (n = 4). Racoon dogs had smaller home ranges than foxes (mean: 52.8 ha). The preferred habitat type of both predators during daytime was the conservation polders along the Wadden Sea, while foxes also selected saltmarshes during the night. In contrast, both species avoided farmland areas. Foxes showed 20% of their activity during daylight hours and spent this time largely in areas with dense vegetation cover. None of the tagged individuals entered areas with particularly high bird densities (i.e. Wadden Sea islands or Halligen). However, our data suggest that foxes and racoon dogs frequently make use of linear structures such as dykes and dams and patrol along the tide line for carcasses. This suggests that at least single individuals of both species are prone to enter islands that are connected by dams to the mainland.
Experimental studies have shown that individual wildfowl can shorten or skip moulting if the time... more Experimental studies have shown that individual wildfowl can shorten or skip moulting if the time between breeding and wintering is short; however, studies in wild birds are scarce. We tracked nine Common Shelducks Tadorna tadorna during the breeding and moulting seasons and determined the flightless time during moulting based on typical movement patterns. We found different movement patterns for two late-breeding females, suggesting that they skipped or shortened the moult of their flight feathers. These results provide a link between previous experimental studies and the situation in wild birds, likely reflecting an individual trade-off between the times allocated to moulting and breeding, respectively. Keywords Tadorna tadorna • Flight feathers • Annual cycle • Wildfowl • Breeding season • Water bird Zusammenfassung Ungewöhnliches Muster einer übersprungenen oder verkürzten Mauser des Fluggefieders bei spät brütenden Brandgänsen Experimentelle Studien haben gezeigt, dass die Mauser bei einzelnen Entenvögeln verkürzt oder übersprungen werden kann, wenn nur wenig Zeit zwischen der Brutzeit und dem Winter liegt. Studien an wildlebenden Vögeln sind jedoch selten. Wir haben neun Brandgänse Tadorna tadorna während der Brut-und Mauserzeit mit Satellitensendern verfolgt und ihre flugunfähige Zeit während der Mauser anhand typischer Bewegungsmuster für diesen Zeitraum bestimmt. Bei zwei spät brütenden Weibchen fanden wir ungewöhnliche Bewegungsmuster, die vermuten lassen, dass sie die Mauser des Fluggefieders übersprungen oder verkürzt haben. Diese Ergebnisse liefern eine Verbindung zwischen früheren experimentellen Studien und wildlebenden Vögeln. Wahrscheinlich spiegeln sie eine notwendige Abwägung zwischen der Zeit wider, welche individuelle Vögel für die Mauser und die Brutzeit zur Verfügung haben.
Understanding fishery impacts is imperative for understanding marine ecology and conservation. Th... more Understanding fishery impacts is imperative for understanding marine ecology and conservation. The global marine fishing industry currently dumps ~10 million tonnes (10%) of their annual catch (Zeller, Cashion, Palomares, & Pauly, 2018), yet discarding is probably one of the least studied component of fishery impacts. Discarding peaked at 18.9 million tonnes in 1989, but has since almost halved (Zeller et al., 2018), and changes in policy, such as discard bans in the European Union (EU Landing Obligation), Norway, Chile and New Zealand, are likely to reduce discarding further (Real et al., 2018). Although bans are desirable for stock management, they may have unforeseen knock-on effects for the mammals, seabirds, fishes and crustaceans that scavenge on discharged biomass (Bicknell, Oro,
Recommendations for project-related studies of possible impacts of marine wind farms during const... more Recommendations for project-related studies of possible impacts of marine wind farms during construction and operation on birds The construction of offshore windfarms may become the largest technical impact on Europe's marine habitats. For roughly a quarter of the area of Germany's Exclusive Economic Zone there are plans to erect offshore windfarms. Several international conventions as well as national laws necessitate environmental impact assessment studies. We hence suggest methods for standardised investigations on the distribution, movements and flight behaviour of birds at sea. They include visual, acoustic and radar-based techniques and observations.
Wetlands such as the World Heritage Site in the Wadden Sea include important habitats for breedin... more Wetlands such as the World Heritage Site in the Wadden Sea include important habitats for breeding waterbirds. Its saltmarshes and adjacent conservation polders are used by thousands of breeding birds. However, some alarming population declines have been recorded during recent decades and previous studies found indications that predation pressure from red foxes (Vulpes vulpes) and more recently from invasive racoon dogs (Nyctereutes procyonoides) played an important role. The current study aimed to assess habitat utilisation by foxes and racoon dogs along the coast of the Wadden Sea. We equipped 21 foxes and seven racoon dogs with GPS collars and recorded a total of 37,586 (mean: 2,088) GPS fixes during a total of 2,617 (mean: 145) equipment days for red foxes and 3,440 (mean: 573) GPS fixes during a total of 272 (mean: 45) equipment days for racoon dogs. Foxes showed high individual variability in Kernel 95% home range sizes, with a mean of 172.2 ha (range: 3 to 824 ha) and little ...
Migration patterns in birds vary in space and time. Spatial patterns include chain, leapfrog and ... more Migration patterns in birds vary in space and time. Spatial patterns include chain, leapfrog and telescopic migration. Temporal patterns such as migration duration, number, and duration of stopovers may vary according to breeding latitude, sex, and season. This study aimed to verify these patterns in a long‐distance migrant, the Eurasian curlew Numenius arquata arquata, and to provide a synopsis of spatio‐temporal migration patterns in this species of concern throughout the East Atlantic Flyway. We tagged 85 adults with GPS‐data loggers in Germany, Poland, France and Estonia between 2013 and 2019. We computed the distance flown, linear loxodromic distance, duration, stopover number, total stopover duration, mean stopover duration, departure time and arrival time for 177 out of 187 tracks. On average (± standard deviation), spring migration occurred from 4 to 14 April (10.2 ± 8.4 days), curlews flew 3.623 ± 1.366 km, and had 5.8 ± 3.6 stopovers, with a duration of 29.4 ± 38.2 h per s...
The Wadden Sea is one of the most important foraging areas for breeding and migrating birds. Howe... more The Wadden Sea is one of the most important foraging areas for breeding and migrating birds. However, little is known about the preferred feeding places of birds and how the intense predation pressure influences the food web. Within the project STopP the trophodynamic structure of different Wadden Sea habitats is determined to get an idea how sediment characteristics and hydrodynamics modify habitats that serve as food sources for birds.
The Wadden Sea is one of the most important stop-over sites for 10 to 12 Million migrating birds ... more The Wadden Sea is one of the most important stop-over sites for 10 to 12 Million migrating birds per year. But little is known about the influence of birds on the entire ecosystem. We conducted Ecological Network Analysis (ENA) in an important resting site in the Wadden Sea to determine the influence of birds on the food web. A large variety of different bird species uses the area for foraging and is included directly or indirectly in most of the pathways. Birds induce a negative impact on their prey items with a positive feedback reaction to the preys’ competitors and food sources. There is also a strong negative impact among the bird compartments probably due to competition between the birds. Changes in the biomass of the birds revealed alterations in the food web structure. With a decline in the avian biomass the system showed a decrease in connectivity and diversity of flows but an increase in recycling. Changes in the bird population could affect the complexity and functioning ...
can be learned about seabird foraging behavior through biologging. I guess the lack of a broader ... more can be learned about seabird foraging behavior through biologging. I guess the lack of a broader context and clear aims is related to the fact that the manuscript forms part of a special issue, and that the authors are trying to show how seabirds can play a part in an ocean observation network. However, in my opinion the manuscript should also be accessible and interesting to readers who’re unfamiliar with COSYNA, and this will require a bit more context, more clearly defined aims, and a discussion of the pros and cons of the chosen approach in terms of reaching those aims.
Background: New wildlife telemetry and tracking technologies have become available in the last de... more Background: New wildlife telemetry and tracking technologies have become available in the last decade, leading to a large increase in the volume and resolution of animal tracking data. These technical developments have been accompanied by various statistical tools aimed at analysing the data obtained by these methods. Methods: We used simulated habitat and tracking data to compare some of the different statistical methods frequently used to infer local resource selection and large-scale attraction/avoidance from tracking data. Notably, we compared the performances of spatial logistic regression models (SLRMs), point process models (PPMs), and integrated step selection models ((i)SSMs) and their interplays with habitat, tracking-device, and animal movement properties. Results: We demonstrated that SLRMs were inappropriate for large-scale attraction studies and prone to bias when inferring habitat selection. In contrast, PPMs and (i)SSMs showed comparable (unbiased) performances for b...
Northern gannets (Morus bassanus) have been ranked as one of the most vulnerable species in terms... more Northern gannets (Morus bassanus) have been ranked as one of the most vulnerable species in terms of collision with offshore wind farm (OWF) turbines, and strong avoidance of OWFs has been documented for this species. Gannets increasingly encounter OWFs within the ranges of their largest breeding colonies along the European coasts. However, information on their actual reactions to OWFs during the breeding season is lacking. We investigated the possible effects of OWFs located 23-35 km north of the colony on Helgoland in the southern North Sea on breeding gannets. GPS tags were applied to 28 adult gannets breeding on Helgoland for several weeks over 2 years. Most gannets (89%) predominantly avoided the OWFs in both years, but 11% frequently entered them when foraging or commuting between the colony and foraging areas. Flight heights inside the OWFs were close to the rotor-blade zone, especially for individuals predominantly avoiding the OWFs. Gannets preferred distances of 250-450 m to the turbines when being inside the OWF. A point process modelling approach revealed that the gannets resource selection of the OWF area compared with the surroundings (outside OWF = up to 15 km from the OWF border) was reduced by 21% in 2015 and 37% in 2016. This study provides the first detailed characterisation of individual reactions of gannets to OWFs during the breeding season and one of the first comprehensive studies of OWF effects on this species based on telemetry data. The documented effects need to be considered during the planning processes for future OWFs, especially those located close to large seabird breeding colonies.
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Papers by Stefan Garthe