Migrant birds have been trapped on the island of Helgoland (southeastern North Sea) since 1909, with methods and sampling effort remaining unchanged throughout the last four decades. In 12 short/medium-distance migrants and 12 long-distance migrants (23 passerines plus the European woodcock) sample sizes were sufficient to calculate mean spring passage (msp) times and to relate these to climate change. All but one species, passing Helgoland en route to their breeding areas (mainly in Scandinavia), show a trend towards earlier msp-time, which is significant in 7 short/medium-distance migrants and 10 long-distance migrants. The msp-times advanced by 0.05-0.28 days per year, short/medium-distance migrants not differing from long-distance migrants. In 23 out of the 24 species, earlier msp-times coincide with local warmer msp-temperatures (significantly in 11 and 7 species of the two groups, respectively). Even more striking is the relation to a large-scale phenomenon, the North Atlantic Oscillation (NAO), during the last four decades. Again, in 23 out of the 24 species, an earlier msp-time coincides with higher NAO indices (significantly in 9 and 12 species, respectively). The NAO index can also explain differences and similarities in spring migration strategies, as well as migration routes within Europe.

Climate is changing at a fast pace, causing widespread, profound consequences for living organisms. Failure to adjust the timing of life-cycle events to climate may jeopardize populations by causing ecological mismatches to the life cycle of other species and abiotic factors. Population declines of some migratory birds breeding in Europe have been suggested to depend on their inability to adjust migration phenology so as to keep track of advancement of spring events at their breeding grounds. In fact, several migrants have advanced their spring arrival date, but whether such advancement has been sufficient to compensate for temporal shift in spring phenophases or, conversely, birds have become ecologically mismatched, is still an unanswered question, with very few exceptions. We used a novel approach based on accumulated winter and spring temperatures (degree-days) as a proxy for timing of spring biological events to test if the progress of spring at arrival to the breeding areas by 117 European migratory bird species has changed over the past five decades. Migrants, and particularly those wintering in sub-Saharan Africa, now arrive at higher degree-days and may have therefore accumulated a 'thermal delay', thus possibly becoming increasingly mismatched to spring phenology. Species with greater 'thermal delay' have shown larger population decline, and this evidence was not confounded by concomitant ecological factors or by phylogenetic effects. These findings provide general support to the largely untested hypotheses that migratory birds are becoming ecologically mismatched and that failure to respond to climate change can have severe negative impacts on their populations. The novel approach we adopted can be extended to the analysis of ecological consequences of phenological response to climate change by other taxa.

Barrett, R. T., Camphuysen, C. J., Anker-Nilssen, T., Chardine, J. W., Furness, R. W., Garthe, S., Hüppop, O., Leopold, M. F., Montevecchi, W. A., and Veit, R. R. 2007. Diet studies of seabirds: a review and recommendations. – ICES Journal of Marine Science, 64. We review the different methods that are used to collect dietary data from marine birds. We consider their limitations and practicalities and emphasize critical data gaps in our knowledge of the feeding ecology of seabirds (na mely diets outside breeding seasons). To enhance comparability of findings among studies, species, and oceanographic regions, we make recommendations on standards for the reporting of results in the literature.

Summary1. 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. 2. 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. 3. 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. 4. 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. 5. 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. 6. 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.

This paper reports on the total distribution of spring migration timing of willow warbler, chiffchaff and pied flycatcher at locations in the UK, Germany, Russia and Finland. This is the first time that high-quality data based on known-effort monitoring has been examined on a continental scale. First arrival dates, commonly reported in the literature, were positively correlated with mean arrival dates although they would not make good predictors of the latter. At all locations, at least one aspect of the arrival distribution of each species had got significantly earlier in recent years. The trend towards earliness was associated with warmer local temperatures and more positive winter North Atlantic Oscillation index. In years that were early, the arrival distribution became more elongated and skewed. Researchers should now investigate the consequences of earlier arrival on current and future bird populations.