Protected areas for seabirds in German offshore waters: Designation, retrospective consideration and current perspectives

Abstract. Population-level estimates of species' distributions can reveal fundamental ecological processes and facilitate conservation. However, these may be difficult to obtain for mobile species, especially colonial central-place foragers (CCPFs; e.g., bats, corvids, social insects), because it is often impractical to determine the provenance of individuals observed beyond breeding sites. Moreover, some CCPFs, especially in the marine realm (e.g., pinnipeds, turtles, and seabirds) are difficult to observe because they range tens to ten thousands of kilometers from their colonies. It is hypothesized that the distribution of CCPFs depends largely on habitat availability and intraspecific competition. Modeling these effects may therefore allow distributions to be estimated from samples of individual spatial usage. Such data can be obtained for an increasing number of species using tracking technology. However, techniques for estimating population-level distributions using the telemetry data are poorly developed. This is of concern because many marine CCPFs, such as seabirds, are threatened by anthropogenic activities. Here, we aim to estimate the distribution at sea of four seabird species, foraging from approximately 5,500 breeding sites in Britain and Ireland. To do so, we GPS-tracked a sample of 230 European Shags Phalacrocorax aristotelis, 464 Black-legged Kittiwakes Rissa tridactyla, 178 Common Murres Uria aalge, and 281 Razorbills Alca torda from 13, 20, 12, and 14 colonies, respectively. Using Poisson point process habitat use models, we show that distribution at sea is dependent on (1) density-dependent competition among sympatric conspecifics (all species) and parapatric conspecifics (Kittiwakes and Murres); (2) habitat accessibility and coastal geometry, such that birds travel further from colonies with limited access to the sea; and (3) regional habitat availability. Using these models, we predict space use by birds from unobserved colonies and thereby map the distribution at sea of each species at both the colony and regional level. Space use by all four species' British breeding populations is concentrated in the coastal waters of Scotland, highlighting the need for robust conservation measures in this area. The techniques we present are applicable to any CCPF.

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“…and secondly, the establishment of marine SPAs around important foraging areas (Garthe et al. , Perrow et al. ).…”

Section: Introductionmentioning

confidence: 99%

Breeding density, fine‐scale tracking, and large‐scale modeling reveal the regional distribution of four seabird species

Wakefield

Owen

Baer³

et al. 2017

Ecological Applications

107

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“…During the non-breeding season about 84,200-186,000 individuals stay in the Baltic Sea, the North Sea and the NE-Atlantic (BirdLife International 2018;Dierschke et al 2012). Around 20% of the NW-European wintering population occurs in the German Bight (Dierschke et al 2012;Garthe et al 2007;Mendel et al 2008) classifying it as an internationally important staging area for these birds, especially in spring before migration starts (Garthe et al 2012(Garthe et al , 2015. To date three studies have been published on the prey composition of non-breeding red-throated divers in the North Sea and the Baltic Sea, which analysed gut contents using morphological tools (Table 1).…”

Section: Introductionmentioning

confidence: 99%

The diet of red-throated divers (Gavia stellata) overwintering in the German Bight (North Sea) analysed using molecular diagnostics

et al. 2019

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In Europe, the German Bight is one of the most important non-breeding areas for protected red-throated divers (Gavia stellata). It is unclear what attracts the birds to this area, especially as the food composition of seabirds outside the breeding season is notoriously difficult to study. To obtain information on prey species composition of red-throated divers in this area, faecal samples from 34 birds caught alive were analysed using DNA metabarcoding. Prey DNA was detected in 85% of the samples with a mean number of 4.2 ± 0.7 taxa per sample (n=29). Altogether we found a broad prey spectrum with 19 fish taxa from 13 families dominated by five groups: clupeids, mackerel, gadoids, flatfish and sand lances with clupeids being the most frequently detected prey. Our results indicate that red-throated divers are generalist opportunistic feeders in the German Bight, but pelagic schooling fish that aggregate at frontal zones and have a high energetic value might be favoured. Atlantic mackerel appears to be a more important prey for redthroated divers in this area than previously thought. The precision achievable using metabarcoding has revealed a number of prey species that are consumed by red-throated divers in the German Bight, which helps to explain the selection of this area by divers in winter and spring.

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“…For many practical applications, detailed maps of sensitive habitats or communities of endangered birds exist (e.g. Koffijberg et al 2003;Garthe et al 2012). This additional information must obviously be taken into account.…”

Section: Discussionmentioning

confidence: 99%

“…Stock sizes and population dynamics are well known and monitored in the region (e.g. Koffijberg et al 2003;Garthe et al 2012). In some areas, stocks can reach far more than 100,000 individuals.…”

Section: Introductionmentioning

confidence: 99%

Effects of chemical dispersants on oil spill drift paths in the German Bight—probabilistic assessment based on numerical ensemble simulations

et al. 2016

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Oil dispersed in the water column remains sheltered from wind forcing, so that an altered drift path is a key consequence of using chemical dispersants. In this study, ensemble simulations were conducted based on 7 years of simulated atmospheric and marine conditions, evaluating 2,190 hypothetical spills from each of 636 cells of a regular grid covering the inner German Bight (SE North Sea). Each simulation compares two idealized setups assuming either undispersed or fully dispersed oil. Differences are summarized in a spatial map of probabilities that chemical dispersant applications would help prevent oil pollution from entering intertidal coastal areas of the Wadden Sea. High probabilities of success overlap strongly with coastal regions between 10 m and 20 m water depth, where the use of chemical dispersants for oil spill response is a particularly contentious topic. The present study prepares the ground for a more detailed net environmental benefit analysis (NEBA) accounting also for toxic effects.

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Protected areas for seabirds in German offshore waters: Designation, retrospective consideration and current perspectives

Cited by 18 publications

References 17 publications

Breeding density, fine‐scale tracking, and large‐scale modeling reveal the regional distribution of four seabird species

Breeding density, fine‐scale tracking, and large‐scale modeling reveal the regional distribution of four seabird species

The diet of red-throated divers (Gavia stellata) overwintering in the German Bight (North Sea) analysed using molecular diagnostics

Effects of chemical dispersants on oil spill drift paths in the German Bight—probabilistic assessment based on numerical ensemble simulations

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