Neustadt an der Weinstraße, Germany
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Saino N.,University of Milan | Ambrosini R.,University of Milan Bicocca | Rubolini D.,University of Milan | Von Hardenberg J.,CNR Institute of Neuroscience | And 8 more authors.
Proceedings of the Royal Society B: Biological Sciences | Year: 2011

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. © 2010 The Royal Society.

Custer C.M.,U.S. Geological Survey | Custer T.W.,U.S. Geological Survey | Thyen S.,Schlossstrasse 30 | Becker P.H.,Institute For Vogelforschung Vogelwarte Helgoland
Environmental pollution (Barking, Essex : 1987) | Year: 2014

The composition of polychlorinated biphenyl (PCB) congeners was compared between non-incubated and embryonated eggs of tree swallows (Tachycineta bicolor) and little terns (Sterna albifrons) to determine if measurable changes in PCB congeners occurred during the embryonic period. There was no indication of changes in PCB congener patterns over the incubation period in tree swallows in 1999 and 2000 at a site with very high PCB exposure or a site with more modest PCB exposure. Additionally, congeners known to be either quickly metabolized or conserved based on experimental studies did not generally respond as predicted. Similarly, PCB congener patterns in eggs of little terns from Bottsand, Schleswig-Holstein, Germany, did not differ between non-incubated and embryonated eggs. The results from both species suggest that the stage of incubation is not an important consideration when evaluating PCB congener patterns; comparisons and assessments can be made with eggs collected at all stages of incubation. Published by Elsevier Ltd.

Benito M.M.,University of Barcelona | Schielzeth H.,Bielefeld University | Gonzalez-Solis J.,University of Barcelona | Becker P.H.,Institute For Vogelforschung Vogelwarte Helgoland
Journal of Avian Biology | Year: 2013

Adaptive sex allocation has frequently been studied in sexually size dimorphic species, but far less is known about patterns of sex allocation in species without pronounced sexual size dimorphism. Parental optimal investment can be predicted under circumstances in which sons and daughters differ in costs and/or fitness returns. In common terns Sterna hirundo, previous studies suggest that sons are the more costly sex to produce and rear. We investigated whether hatching and fledging sex ratio and sex-specific chick mortality correlated with the ecological environment (laying date, clutch size, hatching order and year quality) and parental traits (condition, arrival date, experience and breeding success), over seven consecutive years. Population-wide sex ratios and sex-specific mortality did not differ from parity, but clutch size, mass of the father, maternal breeding experience and to some extent year quality correlated with hatching sex ratio. The proportion of sons tended to increase in productive years and when the father was heavier, suggesting the possibility that females invest more in sons when the environmental and the partner conditions are good. The proportion of daughters increased with clutch size and maternal breeding experience, suggesting a decline in breeding performance or a resources balance solved by producing more of the cheaper sex. No clear patterns of sex-specific mortality were found, neither global nor related to parental traits. Our results suggest lines for future studies on adaptive sex allocation in sexually nearly monomorphic species, where adjustment of sex ratio related to parental factors and differential allocation between the offspring may also occur. © 2013 The Authors. Journal of Avian Biology © 2013 Nordic Society Oikos.

Arizaga J.,Institute For Vogelforschung Vogelwarte Helgoland | Barba E.,University of Valencia | Alonso D.,Oficina de Anillamiento de Aranzadi | Vilches A.,Oficina de Anillamiento de Aranzadi | Vilches A.,University of Navarra
Ardeola | Year: 2010

Fuel management and stopover duration are parameters of great interest for the understanding of bird migration strategies. Our aim was to study the stopover of bluethroats Luscinia svecica cyanecula in northern Iberia. Data were collected at Badina de Escudera lagoon (reedbeds), Villafranca (42° 16' N 01° 42' W), Ebro Valley. Systematic mist-netting was performed during the autumn migration period between 2003 and 2006. The timing of passage did not vary between age and sex classes, with the bulk of migrants being captured in September. The stopover duration was very long (nearly 30 days) compared to that reported from other stopover sites. Main causes explaining these results could be: (i) an atypical September with unfavourable meteorological conditions, and (ii) the interference of apparently wintering specimens. Apart from a small fraction of birds with very large fuel loads, a mean fuel load of nearly 15 % over lean mass suggests that, if a fraction of migrants stopping-over in Badina overwinter in tropical Africa, they must refuel in areas further south to gain sufficient fuel before crossing the Sahara. Conversely, we cannot rule out that these less loaded birds overwintered within the circum-Mediterranean region. Adults were more fuel loaded than juveniles, but this was not due to a higher fuel deposition rate (mean 0.08 g/day). Bluethroats recaptured from 6 to 10 days after the first capture showed a higher mass deposition rate than those recaptured after 10 days or more. This suggests that birds with long stopovers were not true fuelling migrants, but more probably wintering specimens with balanced energy budgets. A long initial lost of mass (5 days) agrees with both the high competition and the interference of wintering specimens hypotheses. In conclusion, Badina de Escudera, in northern Iberia, is an area used by a true, stopping-over population, as well as by apparently wintering specimens.

Korner-Nievergelt F.,Schweizerische Vogelwarte | Huppop O.,Institute For Vogelforschung Vogelwarte Helgoland
Vogelwarte | Year: 2010

Publishing ornithological data requires the application of adequate statistical methods. With the improvement of methods, software requirements are arising, but available proprietary programs are often far beyond the financial limits of the users. The statistic package R is a free but nevertheless very sophisticated alternative. Regrettably, it is not easy to get started with R since it is not clickable and needs the typing of code. This article is a step by step introduction for R-beginners. The reader can experience the input of data, their handling and visualisation at his computer. We guide the user through a t-test and develop a simple linear model including analysis of residuals. Finally, we suggest books for further reading. © DO-G, IfV, MPG 2010.

Benito M.M.,University of Barcelona | Gonzalez-Solis J.,University of Barcelona | Becker P.H.,Institute For Vogelforschung Vogelwarte Helgoland
Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology | Year: 2011

Carotenoids, as pigments with antioxidant and immunoregulatory properties, play a crucial role in developing chicks. Carotenoids must be acquired through diet and are relatively scarce, suggesting that their availability is a limiting factor leading to a trade-off between colour displays and physiological functions. However, potential differences in this trade-off between male and female chicks have been little studied. We manipulated carotenoid availability in 9 days old common tern Sterna hirundo chicks by supplementing their fish diet with four carotenoids during 9 days. Our aim was to examine sex-specific responses to the experimental increase of dietary carotenoids on plasma circulation, physiological and condition variables and successful fledging. Furthermore, to explore the functional and evolutionary basis of the trade-off, we studied the relationships among carotenoid concentration, mediated immune response and foot colouration. After treatment, control chicks showed decreasing plasma levels for most carotenoid types, whereas supplemented chicks had strong increases. Colour luminosity and saturation increased in both treatment groups, while hue only changed significantly towards redder feet in supplemented females. Supplemented chicks presented neither different T-cell-mediated immunity nor other differences compared to control chicks. Nevertheless, supplemented females showed tendencies towards decreased immune responses and increased δ15N signatures, and supplemented males towards greater body mass. Our results indicate colouration may have, in females, a signalling function as to compensate for immunological costs. In males, additional availability of carotenoids may contribute to improve the body condition. This study suggests that trade-off responses to carotenoid availability are sex-specific in tern chicks. Thus, parental carotenoid supply to chicks may be an unrecognised component in sex allocation. © 2010 Springer-Verlag.

Dittmann T.,Institute For Vogelforschung Vogelwarte Helgoland | Becker P.H.,Institute For Vogelforschung Vogelwarte Helgoland
Gefahrstoffe Reinhaltung der Luft | Year: 2012

OSPAR has formulated Ecological Quality Objectives (EcoQOs) for contamination of coastal bird eggs with mercury and organochlorines. In this pilot study we describe spatial and temporal patterns of egg contamination around the North Sea with regard to the fulfillment of the EcoQOs. Concentrations of Hg, PCB, DDT, HCB and HCH were analyzed in two tern species' and Oystercatcher eggs collected between 2008 and 2010 at 21 sites in seven countries. Concentrations of Hg, PCB and HCB were highest in the southern sites, while those of DDT and HCH were highest in the western North Sea and the Elbe estuary. There were rarely any consistent decreases over time for any compounds. In the tern eggs, Hg, HCB and HCH increased at most sites, PCB and DDT did so in Sweden and Norway and at one or, respectively, several sites in Germany. In the Oystercatcher eggs, HCB and HCH increased at more than half of the sites, PCB, DDT and Hg at several German sites. For the terns, Hg, PCB and DDT exceeded the EcoQO at all sites, HCB did so at most of them. At most sites, HCH fulfilled the EcoQO in some study years. For the Oystercatcher, Hg, PCB and DDT exceeded the EcoQO in all or most years and at most sites. On the other hand, HCB and HCH fulfilled the EcoQO in some or all years at most sites. The EcoQO was exceeded most frequently in estuaries. A comparison with long-term trends suggests that the short-term increases reflect fluctuations around a level, which evens out. We conclude that EcoQOs are suitable for describing contamination patterns of the coastal North Sea in an easily understandable manner, offering the opportunity to harmonise the EcoQOs with coordinated environmental monitoring programmes (CEMP).

Becker P.H.,Institute For Vogelforschung Vogelwarte Helgoland | Zhang H.,Institute For Vogelforschung Vogelwarte Helgoland
Journal of Ornithology | Year: 2010

Replacement clutches may increase the annual reproductive output of individuals and the population, but cause additional effort and may have fitness consequences. Whether longevity and lifetime reproductive success are affected by renesting is unknown. In an individual-based long-term study (1992-2009) we investigated Common Terns Sterna hirundo breeding at the colony site "Banter See" on the German North Sea coast and marked with transponders. This approach allowed us to study short-term as well as long-term consequences of relaying for both the population and individuals. In 5 of 7 years characterized by higher relaying activity, breeding success of replacement clutches was similar or even higher than that of first clutches, but in the total study period only 4.5% of all fledglings (4.4% of natal recruits) stemmed from replacement clutches. Demographic effects of relaying were minor. In most years, relaying birds were able to increase their annual reproductive output through the replacement clutch. Relaying Common Terns were high quality individuals, arriving and laying earlier, and characterized by higher age and body condition than non-relaying conspecifics. Relaying probability decreased with delayed arrival and laying date of first clutch. Survival to the next year did not differ between breeders with or without a replacement clutch. In the lifetime perspective, individuals with at least one renesting event had higher survival, longevity, lifetime reproductive success and fitness compared to birds without a replacement clutch. The higher lifetime reproductive success of the renesting individuals was achieved by a longer lifespan as well as by the reproductive output due to relaying. The positive links between survival, additional effort for replacement clutches and their success are obviously due to the fact that only those individuals relay that can cope with the additional effort required for production and care of the replacement clutch. In this way, renesting is an indicator of high individual quality and a benefit for fitness. © 2010 Dt. Ornithologen-Gesellschaft e.V.

Huppop K.,Institute For Vogelforschung Vogelwarte Helgoland | Huppop O.,Institute For Vogelforschung Vogelwarte Helgoland
Vogelwarte | Year: 2010

Within a project supported by the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety dealing with possible consequences of offshore wind farms on bird migration observations of migrating birds were carried out on three islands in the German Bight, Sylt, Helgoland and Wangerooge, from autumn 2003 to the end of 2006. With "seawatching" the migration of mostly larger species (waterbirds in the broadest sense) over the sea was recorded and "islandwatching" concentrated on the migration of smaller species (mostly passerines) over land (islands in this case). The particular goal of this study is the synoptic observation at three locations at least during the migration periods. Apart from some exceptions, at all three sites seawatching showed the highest migration intensity in the morning hours, much less migration occurred at midday and in the evening. Varying proportions of species are mainly caused by the different breeding and staging/wintering areas, whereby the three sites are touched by the birds to a greater or lesser extent. This phenomenon is most obvious in geese. With seawatching in the first three hours after sunrise a total of 185 species was recorded (154 near Sylt, 137 near Helgoland and 148 near Wangerooge). For 23 species, which were abundant or are regarded to be critical concerning effects of offshore wind turbines, the seasonal and daily patterns of migration intensity are described and shown in graphs, diurnal variation of migration intensity for 15 species and flock size for 11 species. In many species, migration was more intense near Sylt in autumn and near Wangerooge in spring, whereas a more balanced relation of the two migration periods was typical for Helgoland. During both seasons the daily migration intensity of the three sites was highly significantly correlated. That holds true for the overall picture of all species as well as for the migration intensities of many particular species. Due to the geographical locations of the breeding and wintering areas of most species, a general direction of migration along a SW-NE-axis can be expected. However, the results of seawatching could prove this only for Helgoland. Near Sylt and Wangerooge, most birds followed the coastline, i.e. they migrated along a S-N-axis and W-E-axis, respectively. With islandwatching in the first three hours after sunrise a total of 189 species was observed (165 above Sylt, 133 above Helgoland and 161 above Wangerooge). Phenology are described and presented graphically for 23 relatively abundant species, flock size for 10 species. As with seawatching, migration intensity was lower at Helgoland than at the two coastal islands and showed roughly the same amount of birds during spring and autumn migration. As a consequence of the preference of most passerines to migrate along a leading line, migration was stronger for many species in autumn at Sylt and more pronounced in spring at Wangerooge: While relatively few birds headed towards the sea at Sylt (autumn) and Wangerooge (spring), the great majority of birds followed the coastline southward (Sylt in autumn) and eastward (Wangerooge in spring), respectively. Obviously, passerines avoided to fly towards the open sea during daytime and followed the coastline instead. Hence, the few birds arriving from sea produced low migration intensities at Sylt in spring and at Wangerooge in autumn. The SW-NE-direction predominating in bird migration in Central Europe was only approved at Helgoland. But even there, jetties of the harbour acted as leading lines, because in autumn many passerines left the island towards SE and S. Because of the leading line effects at Wangerooge (spring) and Sylt (autumn) the connection was strongest between the sites representing migration over sea, i.e. between Helgoland and arrivals above Sylt in spring, but between Helgoland and arrivals above Wangerooge in autumn. This held true for all species toeether as well as for the single species. © DO-G, IfV, MPG 2010.

Huppop K.,Institute For Vogelforschung Vogelwarte Helgoland | Dierschke J.,Institute For Vogelforschung Vogelwarte Helgoland | Hill R.,Avitec Research GbR | Huppop O.,Institute For Vogelforschung Vogelwarte Helgoland
Vogelwarte | Year: 2012

With regard to potential sites for the construction of offshore wind farms and to their possible threats for birds it is essential to enlarge the current knowledge on bird migration above the sea - especially during the night. Within a comprehensive study for the evaluation of offshore wind farms bird calls were registered automatically on a research platform in the south-eastern North Sea. The species identification of nocturnally migrating birds is almost exclusively possible only by means of their calls. Here, we present species-specific bird occurrence near an anthropogenic offshore structure in the total daily and yearly course on the basis of automatically registered calls. From 2004 to 2007, a total of 100 species was identified. Calls from 95,318 individuals (excluding the large gulls) were used for analyses. Three quarters were passerines (predominantly thrushes), furthermore mainly waders, terns and smaller gulls were detected. 79.4% of all individuals were registered during the night. High numbers of individuals, mostly of several species occurring together, were concentrated in only a few days/nights or even hours. Bird occurrence was much higher during autumn migration than during spring migration. A maximum of 5,236 birds of different species (corresponding to 392 Ind./h) was identified in the night from 28th to 29th October 2005. The migration periods of the short-/medium distance migrants were clearly distinguishable, otherwise not those of the long-distance passerine migrants, presumably due to their much minor ambition to call. In July mainly smaller gulls and terns, in August above all terns and waders (especially Redshank) and in winter some late smaller gulls and thrushes were registered. Generally, numbers increased continually with the beginning of the night and reached a maximum before sunrise. The fewest birds were detected in the late afternoon. Despite methodological constraints, the shown species-specific phenologies broadly match the migration times in the offshore area of the German Bight as recovered by trapping and/or by scheduled or coincidental visual observations of bird migration. Like these methods the acoustic recording cannot cover the whole occurrence of birds. Presumably, the number of birds is underestimated during fine and overestimated during adverse weather when birds reduce flight altitude. However, we assume that the birds registered acoustically on the platform reflect at least the low flying proportion of the calling species in the course of the year and in their daily variability. The opportunity to estimate numbers of low and thereby close to an anthropogenic obstruction flying birds using calls is - with regard to the evaluation of its collision risk and the introduction of mitigation and avoidance measures (site, short-term shutdown of the construction and optimization of illumination) - not exiguous. © DO-G, IfV, MPG 2012.

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