Bettina Mendel

Christian-Albrechts-Universität zu Kiel, Kiel, Schleswig-Holstein, Germany

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Publications (9)10.36 Total impact

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    ABSTRACT: Here, we discuss the scientific rationale behind the identification and selection of marine protected areas (MPAs) for birds in the German Exclusive Economic Zones of the North Sea and the Baltic Sea, based on the European Union (EU) Birds Directive. Seabird distributions were determined using internationally standardised transect counts from ships and aircraft. Their distributions were analysed using geostatistical interpolation methods to derive concentration areas for each species. Two Special Protection Areas (SPAs) were proposed based on the distributions of all species. These were subsequently evaluated by the relevant nature conservation authorities and finally designated by the Federal Environmental Ministry. Long-term data on seabird abundance and distribution collected during and after the SPA designation process revealed the same major concentration areas as in the preceding years, indicating that the overall observed patterns were stable and reproducible, despite small-scale spatial and inter-annual variations. The designation concepts provided by the EU Birds Directive thus appear to be suitable for the appropriate designation of MPAs for birds in offshore waters. However, adequate management tools for European offshore MPAs for birds, e.g. the regulation of fisheries and shipping, still remain to be developed and implemented.
    Biological Conservation 01/2012; 156:126–135. · 3.79 Impact Factor
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    Vogelwelt. 01/2012; 133:163-194.
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    ABSTRACT: Most anthropogenic influences on marine ecosystems, except for river- or terrestrial-borne pollution, involve some sort of vessel activity. Increasing anthropogenic activities mean that many countries are being forced to develop spatial planning schemes, while at the same time implementing conservation sites for sensitive species at sea. The effects of ship traffic on seabirds sensitive to human disturbance are currently too poorly understood to allow for the development of proper planning and conservation guidelines. We therefore used aerial surveys and experimental disturbance to elucidate the effects of passing ships on the distribution patterns, habitat loss, and species-specific flight reactions of birds, as well as the potential for habituation. Loons (Gavia spp.) showed clear avoidance of areas with high shipping intensity. Flush distances of four sea duck species differed significantly, with the longest distances recorded for Common Scoters (Melanitta nigra) and the shortest for Common Eiders (Somateria mollissima). Flush distance was positively related to flock size. Among all the sea duck species studied, the duration of temporary habitat loss was longest for Common Scoters. We found indications of habituation in sea ducks within areas of channeled traffic. However, it is questionable if habituation to free-ranging ships is likely to occur, because of their unpredictable nature. We therefore recommend that spatial planning should aim to channel ship traffic wherever possible to avoid further habitat fragmentation and to allow for habituation, at least in some species. Information on the effects of shipping on other seabird species and during different periods of the year is urgently needed, together with information on the effects of different types of boats, including recreational and fishing vessels.
    Ecological Applications 07/2011; 21(5):1851-60. · 3.82 Impact Factor
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    Forschung für ein integriertes Küstenzonenmanagement: Fallbeispiele Odermündungsregion und Offshore-Windkraft in der Nordsee, 01/2010: pages 15-29; Coastline Reports., ISBN: 978-3-9811839-7-9
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    ABSTRACT: Individual migratory schedules and wintering areas of northern gannets Morus bassanus were studied over 2 consecutive winters by deploying geolocation data loggers on breeding adults from the Bass Rock, UK. Northern gannets attended the breeding colony on Bass Rock until between 24 September and 16 October (median: 5 October). Afterwards, individual birds engaged in different migratory behaviour. Of the 22 birds tracked until at least December, 18% wintered in the North Sea and the English Channel, 27% in the Bay of Biscay and the Celtic Sea, 9% in the Mediterranean Sea and 45% off West Africa. Individual winter home ranges as measured by the 75% kernel density contours varied between 8100 and 308500 km<sup>2</sup> (mean = 134000 km<sup>2</sup>). Several northern gannets migrated northwards from Bass Rock after leaving the colony for a stay of a few days to a few weeks, independent of whether they migrated to Africa or other southern areas later. Birds wintering off West Africa migrated to their wintering areas mostly within 3 to 5 wk, usually starting between early and late October. Most of these birds stayed off West Africa for a period of about 3 mo, where they remained in a relatively restricted area. Return migration was initiated between the end of January and mid-February, and took about as long as autumn migration. We conclude that individual gannets display very variable migratory behaviours, with discrete winter home ranges, and we infer that the migration habits of gannets may be changing in response to human impacts on marine ecosystems.
    01/2009;
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    ABSTRACT: Human exploitation and use of marine and coastal areas are apparent and growing in many regions of the world. For instance, fishery, shipping, military, raw material exploitation, nature protection and the rapidly expanding offshore wind power technology are competing for limited resources and space. The development and implementation of Integrated Coastal Zone Management (ICZM) strategies could help to solve these problems. Therefore, suitable spatial assessment, modeling, planning and management tools are urgently needed. These tools have to deal with data that include complex information on different spatial and temporal scales. A systematic approach based on the development of future scenarios which are assessed by combining different simulation models, GIS methods and an integrating set of ecological integrity indicators, was applied in a case study in the German North Sea. Here, the installation of huge offshore wind parks within the near future is planned. The aim was to model environmental effects of altered sea-use patterns on marine biota. Indicators of ecological integrity were used to assess altering conditions and possible ecosystem shifts ranging from systems' degradations to the development of highly productive and diverse artificial reef systems. The results showed that some ecosystem processes and properties and related indicators are sensitive to changes generated by offshore wind park installations while others did not react as hypothesized
    Ecological Indicators. 01/2009;
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    Nicole Sonntag, Bettina Mendel, Stefan Garthe
    Vogelwarte 01/2006; 44:81-112.
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    ABSTRACT: In a field experiment on the island of Helgoland (southeast North Sea), we investigated whether migration strategy or competition between the sexes cause the differential timing of spring migration of male and female northern wheatears (Oenanthe oenanthe) (males migrating earlier). The study included two subspecies, heading towards Greenland/Iceland and Scandinavia, respectively, and is based on colour-ringing and remote weighing of individuals. Despite food offered ad libitum, most Scandinavian birds left the island on the day of arrival or stayed only 1–3days, whereas more than half of Greenlandic/Icelandic birds stayed for up to 12days and refuelled rapidly. In the latter subspecies, males showed a positive correlation of departure fuel load and fuel deposition rate, resembling time-minimizers in optimal migration theory. In contrast, females departed irrespective of fuel deposition rate, with an approximately constant level of fuel stores. This level was lower than in males, but sufficient to enable by-passing of stopover sites en route, allowing us to regard females as time-minimizers also. Since females are not able to reach Greenland without additional refuelling elsewhere and males appeared to have a larger potential for by-passing stopover sites, time-selection seems to be more pronounced in males and may be the reason for earlier migration of males. Intraspecific aggressive interactions between colour-ringed birds were predominantly won by the initiator, by males and by larger birds, whereas fuel load and subspecies did not affect the outcome. Although compared to females, males were more often dominant at the feeding stations or held territories, refuelling patterns could not be explained by dominance. Subordinate or non-territorial birds did not refuel at a lower rate or depart with lower fuel loads than dominant or territorial birds. In non-territorial birds, the restricted access to feeding stations was made up with larger doses of food taken per visit, leading to the same energy intake as that of dominant and territorial birds. Therefore, competition during stopover could be eliminated as the reason for differential timing of migration of male and female wheatears, but this result may be species-specific.
    Behavioral Ecology and Sociobiology 02/2005; 57(5):470-480. · 2.75 Impact Factor
  • Bettina Mendel, Stefan Garthe
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    ABSTRACT: There are not many areas in the German Bight that are not used by humans. Apart from intense pressures such as fisheries and shipping, the installation of offshore wind farms will demand huge areas. Since it is known from other studies that several seabird species are sensitive to disturbances, it is most likely that increasing uses will interfere with their distribution and behaviour. To assess possible impacts of anthropogenic pressures, it is important that they are not only considered as single events but also in a cumulative way. In addition to wind farms, other uses such intense ship traffic are known to influence seabirds distribution. Based on evidence from investigations at existing offshore wind farms in Sweden and Denmark where strong avoidance responses have been shown, the species group of divers (Red-throated Diver Gavia stellata, Black-throated Diver Gavia arctica) is taken as example for particular sensitive species. On the assumption that divers avoid both offshore wind farm areas as well as intensively used shipping lanes, the loss of suitable habitats as well as the number of potentially affected divers is calculated for these two human pressures in the German Bight.