scholarly journals Underestimated scale of songbird offshore migration across the south-eastern North Sea during autumn

Author(s):  
Vera Brust ◽  
Ommo Hüppop

AbstractFlights over open water can be challenging for migrating songbirds. Despite numerous observations of songbirds migrating over remote islands, virtually nothing is known about the proportion of songbirds risking to fly offshore rather than to follow the coastline. By means of large-scale automated radio-telemetry, we individually tracked songbirds during their autumn migration through the German Bight area in the south-eastern North Sea. Our tracking network facilitated the recording of movement patterns over the bay and, for the first time, the estimation of the proportions of individuals embarking on offshore flights from their coastal stopover sites. Our data are consistent with previous observations of decreasing migration densities from nearshore to offshore, i.e. from east to west in autumn. Still, we revealed a considerable proportion of 25% of birds flying offshore. The tendency to fly offshore decreased from west to south migrants, which is in line with optimal bird migration theory. Among south-west migrating species, which also comprise the vast majority of songbird species migrating through the German Bight area, thrushes showed the highest proportions of offshore flights. Considering the recent and ongoing increase of artificial offshore structures, our results suggest that some species or species groups might especially face an increased risk of being negatively affected.

2011 ◽  
Vol 1 (32) ◽  
pp. 27
Author(s):  
Juergen Jensen ◽  
Thomas Wahl ◽  
Torsten Frank

This contribution focuses on presenting the results from analysing mean sea level changes in the German Bight, the south-eastern part of the North Sea. Data sets from 13 tide gauges covering the entire German North Sea coastline and the period from 1843 to 2008 have been used to estimate high quality mean sea level time series. The overall results from nonlinear smoothing and linear trend estimations for different time spans are presented. Time series from single tide gauges are analysed as well as different ‘virtual station’ time series. An accelerated sea level rise in the German Bight is detected for a period at the end of the 19th century and for another one covering the last decades. In addition, different patterns of sea level change are found in the German Bight compared to global patterns, highlighting the urgent need to derive reliable regional sea level projections to be considered in coastal planning strategies.


2004 ◽  
Vol 83 (4) ◽  
pp. 267-285 ◽  
Author(s):  
D.K. Munsterman ◽  
H. Brinkhuis

AbstractAn integrated stratigraphical analysis emphasizing organic-walled dinoflagellate cyst (dinocyst) distribution has been carried out on multiple boreholes penetrating the Miocene in the subsurface of the Netherlands (southern North Sea Basin). The bulk of the investigated successions is attributed to the Breda Formation, a regional lithostatigraphical unit most complete in the south-eastern part of the Netherlands. In concert with a first regional integrated bio (chrono) sequence-stratigraphical framework, fourteen informal dinocyst zones for the southern North Sea Miocene (SNSM), and three subzones are proposed for the Breda Formation. By also integrating (chrono)stratigraphic information from Mediterranean and North Atlantic dinocyst studies a first ever detailed age-model is here proposed for the Miocene in the subsurface of the Netherlands.


2014 ◽  
Vol 16 (1) ◽  
pp. 139-147 ◽  
Author(s):  
Jens Rydell ◽  
Lothar Bach ◽  
Petra Bach ◽  
Laura Guia Diaz ◽  
Joanna Furmankiewicz ◽  
...  

2010 ◽  
Vol 28 (10) ◽  
pp. 1905-1922 ◽  
Author(s):  
M. T. Prtenjak ◽  
I. Tomažić ◽  
I. Kavčič ◽  
S. Đivanović

Abstract. Characteristics of thermally induced flow, namely the sea breeze, are investigated along the south-eastern Adriatic. The chosen period 24–25 April 2006 favoured sea breeze development and simultaneously allowed a comparison of the large-scale wind influence (north-westerly wind versus south-easterly wind) and the complex terrain on the local circulations. Particular attention is paid to the small-scale formation of the wind field, convergence zones (CZs), channelling flows and small scale eddies, especially in the vicinity of two airports in the central part of south-eastern Adriatic. The results are based on wind measurements (from meteorological surface stations, radiosoundings, satellite data and sodar data) and further supplemented by model data at fine grid spacing. This study shows the formation of numerous irregular daytime and nighttime CZs, which occurred along the coastline in the lee of mountains and over the larger, elongated islands. The results show that the above mentioned airports are surrounded by daytime CZ formations within the lowermost 1000 m and associated updrafts of 1 m s−1, especially if CZs are maintained by the north-westerly large-scale winds. Whereas the daytime CZ was generated due to merged sea breezes, the weaker and shallower nighttime CZs were formed by wind convergence of the seaward breezes, and significantly modified by the large-scale flow of the topography (e.g., accelerated flow in the sea channels and substantial swirled flows around the islands). The passes between the coastal mountain peaks changed the inflow penetration, provoking the increase in wind speed of the channelled flow. The strongest sea breeze channelling was observed above the valley of the Neretva River, where the onshore flow reached 40 km inland with a strength of 8 m s−1, and the highly asymmetric offshore part was confined within the sea channel.


2020 ◽  
Vol 53 (4) ◽  
pp. 415-442
Author(s):  
Dorothea Bunzel ◽  
Yvonne Milker ◽  
Katharina Müller-Navarra ◽  
Helge Wolfgang Arz ◽  
Jana Friedrich ◽  
...  

2000 ◽  
Vol 95 (2) ◽  
pp. 209-217 ◽  
Author(s):  
Wim J. Wolff
Keyword(s):  

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