Helgoland Bird Observatory Franz Bairlein

A history of the Institute of Avian Research – Helgoland Bird Observatory Franz Bairlein

Abstract This article was originally published in German in 2010, to help celebrate the centenary of the establishment of a bird observatory on the island of Helgoland, Germany. It describes the beginnings of the observatory, and its development since, highlighting the key personnel involved and the linked establishment of the Institute of Avian Research. The main research themes of the modern era are outlined, with examples, and an appendix describes some of the rare migrant birds recorded on the island of Helgoland.

The beginnings of ornithology on came to Helgoland as a young artist in 1837. Helgoland He subsequently concentrated his artistic Although the occasional mention of talents on the birdlife of the island and, in Helgoland’s birds had been made earlier, it fact, following his marriage to an island girl was Heinrich Gätke who first made the island in 1841, he remained on Helgoland for the and its birds well known. Gätke, born in 1814 rest of his life. in Pritzwalk, in the state of Brandenburg, Gätke’s introduction to ornithology stemmed from his passion for hunting. In October 1843 he shot a young Gyr Falcon Falco rusticolus and, thrilled by the beauty of the bird, he started what was to become a comprehensive collection. He shot and pre- pared many birds himself and acquired others from hunters and amateur taxider- mists on the island. In January 1847 he began to keep a detailed ornithological diary, in which he recorded both ornithological and meteorological data. His accounts of Helgoland’s birds drew many ornithologists to the island yet, gradually, the stream of rarities that Gätke reported also began to attract a degree of scepticism. Critics suggested that the islanders collected the birds elsewhere and brought them to the island in order to sell to collectors at high prices. Gätke reacted sharply to this criticism but doubts about the provenance of the birds were rebutted above

Institute of Avian Research archives all by Johann Heinrich Blasius, who had 148. Heinrich Gätke (1814–1897). studied Gätke’s working methods at first-

290 © British Birds 104 • June 2011 • 290–302 A history of the Helgoland Bird Observatory hand during a visit to the island in 1858. Nonetheless, during this period of contro- versy, Gätke was unable to find a publisher for his magnum opus, which included many of his own sketches and vignettes. Ultimately, Rudolf Blasius published Gätke‘s Die Vogelwarte Helgoland in spring 1891. Gätke sold his skin collection following the handover of Helgoland to the German Empire by the British Governor in August 1890. Together with his scientific library, it was purchased by the Prussian Biological Institute on Helgoland. This formed the basis for the later foundation of the Helgoland Bird Observatory. Sadly, Gätke did not live to experience this for he died on New Year’s Day 1897.

The establishment of Helgoland Bird Observatory In 1909, Hugo Weigold (born 27th May 1886 in Dresden) came to the Helgoland Nagel/J.R. Dierschke 149. The Gyr Falcon Falco rusticolus shot by Biological Institute as assistant to the Heinrich Gätke on Helgoland in October 1843. German Commission for Marine Research. Although Weigold was by profes- sive step for the development of the sion a fisheries biologist, he was also an Helgoland Bird Observatory was the start of enthusiastic ornithologist and he convinced breeding and migrant bird ringing by the director of the Biological Institute, Prof. Weigold, from 1909 onwards. The first bird Heincke, to let him study bird migration ‘on ever ringed on Helgoland, a Song Thrush the side’. Weigold’s intention was the forma- Turdus philomelos, on 16th October 1909, tion of a bird observatory on Helgoland in ring number ‘VOGELWARTE ROSSITTEN parallel to the Rossiten Bird Observatory 1111’, was shot on the island two days later. (subsequently renamed Rybachy), which was Initially, rings from Rossitten were used but, also established in 1910, on the Curonian from summer 1911 onwards, Helgoland rings Spit. The great day came, on 1st April 1910, were introduced with the inscription ‘Zool. when Weigold was entrusted with the Station Helgoland’ (and later ‘Biolog. conduct of ornithological studies. This date Helgoland’). has since come to be considered as the In 1911, a ‘biological experimental garden’ birthday of the ‘Vogelwarte Helgoland’ – was laid out in a hollow (known locally as the Helgoland Bird Observatory. Sapskuhle) on the Middle Land of Weigold continued to publish the ornitho- Helgoland, an area devoid of trees and logical reports begun by Gätke, but the deci- shrubs, and where standing water gathered

The island of Helgoland BOX 1 Helgoland is located 46 km off the German coastline (in the Helgoland Bight, in the southeastern corner of the North Sea) and consists of two islands: the main island, or ‘Hauptinsel’ (around 1 km2, population c. 1,650), to the west and, to the east, the smaller (0.7 km2) island, or ‘Düne’. The former is what the place-name ‘Helgoland’ is normally used to refer to; the latter is lower, surrounded by sandy beaches and not permanently inhabited. Denmark ceded Helgoland to the UK (by the Treaty of Kiel, in January 1814), while Britain gave up the islands to Germany in 1890 in the Helgoland–Zanzibar Treaty.

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died on 9th July 1973 at Ammersee, Bavaria. Dr Rudolf Drost (born on 18th August 1892 in Oldenburg, Lower Saxony) took over the direction of the observatory as Curator for Bird Research on 1st April 1924. In 1926, this became the Observa- tory Department and was housed temporar - ily in a former cable Institute of Avian Research archives shed, some distance 150. The first Institute building on Helgoland, 1931. from the trapping after heavy rain. Weigold planted the garden, garden. The situation improved in October designed for botanical and ornithological 1926 when the Observatory moved to the purposes, with plants donated from the former naval staff offices on the Upper Land, mainland. Birds were originally caught with ‘only 170 paces away from the trapping nets in this garden until the development and garden’. introduction of the now world-famous The trapping garden was gradually Helgoland funnel trap by Weigold in 1920. extended. In 1927, a 2-m-high wall was built The basis for successful bird migration around it. In 1938, a further hollow was research – the long-term trapping pro- created and, in due course, five large funnel gramme – was thereby established. Weigold traps were erected at an angle to the main continued his research into bird migration trap. The scientific bird collection was also until he left Helgoland in 1924 to take up the enlarged and a bird migration museum was post of director of the Hanover State established in 1931. The periodical Der Museum. His numerous reports and scien- Vogelzug [Bird Migration], which changed its tific studies firmly established Helgoland as name to Die Vogelwarte [The Observatory] in the Mecca of ornithology. Dr Hugo Weigold 1949, was founded in collaboration with the Rossitten Bird Obser- vatory and the German Ornitholog- ical Society. In addition to the bird ringing on Helgoland, increasing numbers of birds were ringed by volunteers on the mainland, and so-called ‘branch ringing centres’ were founded in Silesia, Magdeburg, Frank- furt, Marburg, Dessau, Oldenburg and Bremen. By the end of the 1930s, over Institute of Avian Research archives 151. The trapping garden on Helgoland around 1930. Such dense cover 100,000 birds a year is found almost solely in the trapping garden. were being caught and

292 British Birds 104 • June 2011 • 290–302 A history of the Helgoland Bird Observatory Institute of Avian Research archives Institute of Avian Research archives 152. One of the funnel traps on Helgoland, 1934. 153. Dr Hugo Weigold (1886–1973). fitted with Helgoland Bird Observatory rings. the Cultural Department of the Hanover This work was severely restricted during the Province administration. Following the for- Second World War as employees were called mation of the Federal State of Lower Saxony to arms. But work on Helgoland did not (in 1946), the Institute came under the Lower cease altogether. Three female employees not Saxony Cultural Ministry. only looked after the scientific material, but In September 1945 and August 1946, also kept up the daily trapping schedule Drost transported the surviving material during this period and even broke the record from Helgoland to Cuxhaven, a small town for the number of birds trapped in a single on the coast, at the mouth of the Elbe. day (1,510 birds on 12th October 1940 – a During his search for a new home for the record that still stands). Research work on Institute, Drost was invited in 1947 to Helgoland was curtailed only by the massive consider a site in Wilhelmshaven, another bombing attacks by Allied forces on 18th German coastal town. The site, with its aban- April 1945. doned naval buildings, appeared to be ideal for his plans. With the approval of the The post-war era Cultural Ministry, the Institute moved from After release from a prisoner of war camp, Cuxhaven to Wilhelmshaven by boat in Drost opened temporary offices of the Helgoland Bird Observatory on the mainland, in Göt- tingen, in 1945. His aim, however, was to rebuild the bird observatory on the island and his efforts were eventually to be successful. On 1st April 1945, the observatory was taken over as an independent Insti-

tute of Avian Institute of Avian Research archives Research (IAR) by 154. Institute of Avian Research, Wilhelmshaven, 1948.

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initial task was to repair the trapping installations in the Sapskuhle, which had been badly damaged during the war, so that scientific work could restart. Of more pressing importance, however, was the erection of a temporary fence to keep the trapping area secure (from, among other things, courting couples and hunters; Vauk 1977). The only available material was barbed wire, timber beams lying around in the Upper Land and boards swept up on the island’s shores – and some residents saw the fence as an eyesore. In February 1957 the new observatory building next to the Sapskuhle was occupied and, now Institute of Avian Research archives 155. Prof. Dr Rudolf Drost (1892–1971). that better working conditions were available, a new chapter in the observa- September 1947; the Göttingen branch office tory’s history began. followed suit in November that year. A At first, the trapping garden remained a museum was set up in an outbuilding in building site. Old funnel traps were torn 1948 and aviaries and funnel traps were built down and new ones built, trees were felled for captive-bird experiments. and others planted. Paths were paved and decoy bird aviaries were erected. Bomb A new start on Helgoland craters were converted to become the only Despite the progress at Wilhelmshaven, it was freshwater ponds on Helgoland and these still Drost’s intention to have an ornithologist attracted resting migrant and resident stationed on Helgoland once more. In March breeding birds. In 1960, with all work fin- 1953, a year after access to the island was ished and a new fence built, routine trapping finally permitted once again, Dr Wolfgang work resumed and this has continued until Jungfer was posted to Helgoland, and Island the present day. Station Helgoland was founded. Its first For 15 years there was only a single scien- home was in rented warehouse accommoda- tific position on Helgoland but the long- tion in the southern port area. The most hoped-for second post was established on 1st important objective was to rebuild the trap- March 1975. Dr Dieter Moritz took over the ping garden and to restart operations there. A migrant bird research and running of the small funnel trap was soon built, permitting trapping garden while Vauk concentrated on limited trapping and the first post-war seabird ecology and conservation matters. ringing of migrant birds. A small hut was also Ten years later, the island observatory under- built to allow ringing to continue inde- went a major structural expansion with the pendent of weather conditions. inauguration of a new second Institute A new observatory was eventually built at building in 1985, the 75th anniversary year the beginning of 1956, directly adjacent to of the Institute. New laboratories and room the trapping garden so that it could be space provided an increased capacity to viewed from the office windows. An observa- accommodate the indispensable observatory tion tower on top of the building allowed a assistants. Gottfried Vauk left the Helgoland view in all directions, yet with protection Observatory in 1988 to take over as Director from wind and weather. of the Lower Saxony Nature Protection Dr Gottfried Vauk replaced Jungfer on 1st Academy in Schneverdingen. He will always April 1956 and a technical assistant post was be remembered for his immense efforts to established soon afterwards. The following develop the island observatory. Since 1988, years were dominated by the continued Dr Ommo Hüppop has been head of opera- development of the island observatory. The tions on Helgoland.

294 British Birds 104 • June 2011 • 290–302 A history of the Helgoland Bird Observatory

Further developments in Wilhelmshaven Drost had always considered the initial site in Wilhelms haven as an interim solution only and by 1958 he had already identified the former Fort Rüstersiel, on the northern fringes of the town, as an ideal new location for the Institute. Apart from the entrance, the Fort is surrounded by a wide moat – the ‘Graft’ – and the site is covered with trees and shrubs. Moreover, those buildings not damaged during the war could be refurbished and extended. The process of moving to the new site took several years to complete and it was not until 10th March 1965 that the Institute was finally settled at this new location. By now, the IAR was under the supervi- sion of Dr Friedrich Goethe, who had Institute of Avian Research archives taken over from Prof. Drost as scientific 156. Dr Friedrich Goethe (1911–2003). director in September 1958. Goethe (born on 30th June 1911 in Kiel) The Brunswick Outstation for made his first contact with the observatory as Population Biology a 15-year-old schoolboy assistant on the East A department for Population Biology, with Friesian island of Mellum. In 1951 he came its offices in Cremlingen-Weddel, near to the Helgoland Observatory at the IAR as a Brunswick (Braunschweig), was affiliated to scientific assistant. Goethe completed the the Institute in 1967 under Goethe’s direc- building and development of the Institute at tion. This facility was founded by Dr Rudolf its new location in Wilhelmshaven-Rüster- Berndt in 1947 as the Brunswick ornitholog- siel, as well as the development and design of ical protection station of the state-recognised the Institute’s Heinrich Gätke Hall, which Lower Saxony Bird Conservation Agency. was inaugurated in 1972. He retired in 1978 Berndt headed the Brunswick outstation and died on 3rd January 2003. until 1978, when his successor was Dr Institute of Avian Research archives 157. The former Fort Rüstersiel with its moat, the Graft, now the head office of the Institute of Avian Research in Wilhelmshaven.

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studying birds under con- trolled conditions at Wil- helmshaven and, in addition, the main building was extended and the ringing work and centre were restructured. Nicolai also masterminded a complete reorganisation of the scientific personnel. In 1978, Dr Peter H. Becker was appointed to the vacant scientific post. He was instru- mental in an expansion of the ecologically oriented coastal Institute of Avian Research archives 158. The Brunswick Outstation for Population Biology in bird research and the start of Cremlingen-Weddel (in use from 1967 to 2000). long-term trans-regional projects. Permanent staff Wolfgang Winkel, who had been employed as numbers were strengthened when a further a scientific assistant in Wilhelmshaven since scientific post was created and filled by Dr 1970. Winkel continued as head until the Klaus-Michael Exo. Together with the two department’s closure at the end of 2000. He permanent scientific posts established on continued his scientific studies in the Popula- Helgoland and one at Brunswick, this meant tion Ecology Working Group until his retire- that a total of six permanent scientific posts ment in 2006. were filled. New field research methods, such as radio telemetry and the automatic The modern era weighing of individual birds while incubating In 1977, Prof. Dr Jürgen Nicolai succeeded their clutches, were also introduced. Jürgen Goethe as the Institute’s Director. Born on Nicolai retired on 31st October 1990 and 24th October 1925 in Neidenburg, East died on 29th March 2006. Prussia, Nicolai worked at the newly founded Prof. Dr Franz Bairlein has been Institute (1957) Max Planck Institute before moving Director since 1st November 1990. The focus to the IAR at Wilhelmshaven. He oversaw a of his research is bird migration, ranging significant expansion of the facilities for from investigation of the physiological Institute of Avian Avian ResearchInstitute of archives Institute of Avian Research archives 159. Prof. Dr Jürgen Nicolai 160. Prof. Dr Franz Bairlein, Institute Director since (1925–2006). November 1990.

296 British Birds 104 • June 2011 • 290–302 A history of the Helgoland Bird Observatory mechanisms by which migrant birds accrue body fat, to ecological studies of European species in stopover areas along their migration routes and in their winter quarters. The research on bird migration at the Institute has gained new momentum as a result. At the beginning of the 1990s, some modernisation of the main buildings at Wilhelmshaven took place, for example the library was extended and new study

rooms and laboratories Bairlein Franz constructed. In addition, 161. Today’s observatory on Helgoland. Older buildings from 1956 the experimental facilities with duty apartments and observation tower to the left, and the were completely redevel- newer Institute building, inaugurated in 1985, to the right. oped and extended. On 7th December 2009, a cere- mony took place to mark further redevelopment and renovation of the buildings, which will ensure that the Institute remains interna- tionally competitive in the future. The Institute today reports to the Lower Saxony Ministry for Science and Culture and consists of the head office in Institute of Avian Research archives Wilhelms haven and the 162. The Institute main building at Wilhelmshaven in 2004. Helgoland island observatory. In addition to the Director and his from universities and high schools at home deputy, the staff consists of four scientific and abroad are involved. The Institute has employees, of which two have contracts numerous links with other organisations and lasting a maximum of five years, and 19 tech- institutions, at both national and interna- nical assistants. A fluctuating number of tional level, which is so important for additional scientific and technical institute modern science in today’s world. staff is paid for from third-party funds. In The Institute’s scientific work is moni- addition, there are two workers on civilian tored by an advisory body consisting of eight service, up to four volunteers engaged on scientists appointed by the Lower Saxony one-year contracts, and a large number of Ministry for Science and Culture. Since 1993 part-time volunteers who are employed on the Institute has published the biennial Insti- numerous field studies and in the trapping tute of Avian Research Annual Report, which garden on Helgoland. Without the commit- includes details of ongoing studies and the ment of all these staff and volunteers, the Institute’s work in summary form. The continuation of many long-term studies Annual Report is aimed at interested would be impossible. In addition, a fluctu- members of the public and is available at ating number of students at varying levels www.vogelwarte-helgoland.de

British Birds 104 • June 2011 • 290–302 297 Bairlein Markus Varesvuo Markus 163. Much of the current bird migration research on Helgoland is focused on the Northern Wheatear Oenanthe oenanthe – see, for example, the summary by Franz Bairlein in Brit. Birds 101: 68–81. Highlights of recent research 2010). Other key topics are long-term trends Bird migration research in migration phenology and population Since the foundation of the Helgoland Bird changes of migratory species, for which the Observatory on 1st April 1910, bird migra- 50 years of standardised trapping data from tion research has been a central theme of the the island of Helgoland provide an out- scientific work of the IAR. Over that time, its standing source of information (Hüppop & focus has developed significantly, of course. Hüppop 2002–09; Saino et al. 2010). For a long time, migration routes were clari- fied with the help of ringing; today, studies Population biology concentrate on the search for the mecha- The second main research focus of the IAR is nisms of the internal and external factors and population biology. This attempts to explain mechanisms controlling migration, under- the extent to which bird populations are standing migration strategies, and long-term influenced by environmental changes and changes in migration behaviour. We now also which demographic processes have a role to use modern electronic marking methods, play. Populations cannot survive or repro- such as satellite telemetry and geolocation, duce without an adequate food supply. which permit the acquisition of data on long- Recent research has shown that only a few term migration strategies over a short individuals are responsible for the produc- timescale. We combine field and laboratory tion of the majority of offspring for the next studies on stopover behaviour and physi- generation. This raises exciting new questions ology in order to improve understanding of such as the identification of the characteris- the dependence of migration behaviour on tics of those individuals with special quali- internal and external factors. The current ties. target species is the Northern Wheatear Oenanthe oenanthe (Dierschke et al. 2005; Focus on the individual – the survival Schmaljohann & Dierschke 2005; Delingat et strategy of the Common Tern al. 2006, 2008, 2009, 2010; Bairlein 2008; The life-cycle of long-lived vertebrates has Schmaljohann et al. 2010; Maggini & Bairlein attracted more and more research interest

298 British Birds 104 • June 2011 • 290–302 A history of the Helgoland Bird Observatory over the past few years. The IAR undertakes the decades many different themes have been an individual-based, long-term study of a studied, ranging from classic breeding and Common Tern Sterna hirundo colony where behavioural biology, to dietary ecology and hundreds of individuals are marked with PIT associated questions about the protection of (Passive Integrated Transponder) tags. Evolu- nature and the environment, and to the tion begins with the individual, which in the highly contemporary aspects of population course of its long life goes through multiple ecology. The variety and complexity of the changes, whereby learning processes also play relationships between birds and their envir - an important role. The differences between onment are enormous. We focus on the role individuals are considerable and only a few of food supply availability and long-term birds produce sufficient young in their life- changes in population size and behaviour of time to contribute to the next generation. birds of the southern North Sea and the Only if we begin to understand the causes Wadden Sea (Hüppop & Wurm 2000; Bair- and consequences of the differences in lein & Exo 2007; Ezard et al. 2007; van de Pol quality between individuals, and age- et al. 2010; Dänhardt et al. 2011a,b). dependent development, will we be able to explain demographic changes and to design Basic principles of environmental effective species protection measures (Becker protection et al. 2008; Dittmann et al. 2007; Bauch et al. Birds play a prominent role not only in 2010; Limmer & Becker 2010; Rebke et al. nature and environment protection and the 2010; Becker & Zhang 2011; Benito et al. designation of nature reserves, but also in the 2011). evaluation of habitats and associated management measures. Research is vital for the Seabird and coastal bird ecology understanding of these aspects. Through its The biology of sea and coastal birds has research, the IAR provides significant raw always been of particular interest to an insti- data that relate in a variety of ways to applied tute that was founded ‘in the middle of the environmental research. Studies concentrate ocean’ and which, even after its move to Wil- on subjects including ‘Seabirds as bio-indica- helmshaven, lies ‘just behind the dyke’. Over tors’, the ‘Wadden Sea ecological system’ as Markus Varesvuo Markus 164. The IAR undertakes an individual-based, long-term study of a Common Tern Sterna hirundo colony where hundreds of individuals are marked with PIT (Passive Integrated Transponder) tags.

British Birds 104 • June 2011 • 290–302 299 Bairlein well as ‘Bird migration and wind turbines’ J. Comp. Physiol. B 180: 835–845. (Exo & Thyen 2003; Muñoz Cifuentes 2004; Becker, P. H., & Dittmann, T. 2009. Contaminants in bird eggs. Thematic Report No. 5.2. In: Marencic, H., & Thyen & Exo 2005; Hüppop et al. 2006; de Vlas, J. (eds.), Quality Status Report 2009. Wadden Becker & Dittmann 2009). Sea Ecosystem No. 25, Wilhelmshaven. www.waddensea-secretariat.org/ Ringing centre QSR-2009/index.htm —, & Zhang, H. 2011. Renesting of Common Terns In addition to its scientific work, the IAR is Sterna hirundo in the life history perspective. J. Orn. the home of the Helgoland ringing centre. Special Issue: doi: 10.1007/s10336-010-0639-0. The centre was previously responsible for —, Dittmann, T., Ludwigs, J-D., Limmer, B., Ludwig, S., Bauch, C., Braasch, A., & Wendeln, H. 2008. Timing ringing in many parts of Germany but, since of initial arrival at the breeding site predicts age at the foundation of the Federal Republic of first reproduction in a long-lived migratory bird. Germany, its responsibility is restricted to the Proc. Nat. Acad. Sci. 105: 12349–12352. northwest federal states of Lower Saxony, Benito, M. M., González-Solís, J., & Becker, P. H. 2011. Carotenoid supplementation and sex-specific trade- Bremen, Hamburg, Schleswig-Holstein, offs between coloration and condition in Common North-Rhine Westphalia and Hessen. Tern chicks. J. Comp. Physiol. B: doi: 101007/s00360- From the very beginning, bird ringing was 0537-z dependent on the assistance of numerous Dänhardt, A., Fresemann, T., & Becker, P. H. 2011a. To eat or to feed? Prey utilization of Common unpaid volunteers – the ringers. At present Terns Sterna hirundo in the Wadden Sea. J. Orn. the IAR can count on some 260 volunteer doi: 10.1007/s10336-010-0590-0 ringers within its area of responsibility. —, —, & — 2011b. Does small-scale vertical Without the committed co-operation of this distribution of juvenile schooling fish affect prey availability to surface-feeding seabirds in the group, a comprehensive scientific ringing Wadden Sea? J. Sea Res. programme could not be supported. Whereas doi: 10.1016/j.scitotenv.2010.10.043 in the past the aim was to ring as many birds Delingat, J., Bairlein, F., & Hedenström, A. 2008. from a wide variety of species as possible, Obligatory barrier crossing and adaptive fuel management in migratory birds: the case of the today the focus is on programmed scientific Atlantic crossing in Northern Wheatears (Oenanthe bird-marking. oenanthe). Behav. Ecol. Sociobiol. 62: 1069–1078. Since the formation of Helgoland Bird —, Dierschke, V., Schmaljohann, H., & Bairlein, F. 2009. Diurnal patterns of body mass change during Observatory in 1910, almost nine million stopover in a migrating songbird, the Northern birds of a total of 585 species (or identifiable Wheatear Oenanthe oenanthe. J. Avian Biol. 40: subspecies) have been ringed. Of these, some 625–634. 250,000 ring-recoveries from 307 species —, —, —, Mendel, B., & Bairlein, F. 2006. Daily stopovers as optimal migration strategy in a long- have been recorded, distributed virtually distance migrating passerine: the Northern right across the world. All ring-recoveries are Wheatear. Ardea 94: 593–605. registered in an electronic database, coded —, Hobson, K. A., Dierschke, V., Schmaljohann, H., & according to a common European key and Bairlein, F. 2010. Morphometrics and stable isotopes differentiate populations of Northern Wheatears are freely available for analysis. They are also (Oenanthe oenanthe). J. Orn. doi: 10.1007/s10336- held in the database of all European ringing 010-0599-4 centres, which is administered by the Euro- Dierschke, V., Mendel, B., & Schmaljohann, H. 2005. pean Union for Bird Ringing (EURING). Differential timing of spring migration in Northern Wheatears Oenanthe oenanthe: hurried males or weak females? Behav. Ecol. Sociobiol. 57: 470–480. References and further reading Dittmann, T., Ezard, T. H. G., & Becker, P. H. 2007. Bairlein, F. 2008. The mystery of bird migration – still Prospectors’ colony attendance is sex-specific and a lot to be learnt. Brit. Birds 101: 68–81. increases future recruitment chances in a seabird. — & Becker, P. H. (eds.) 2010. 100 Jahre Institut für Behav. Processes 76: 198–205. Vogelforschung ‘Vogelwarte Helgoland’. Aula, Drost, R. 1956. Geschichte der Vogelwarte Helgoland. Wiebelsheim. In: Steiniger, F. (ed.), Natur und Jagd in Niedersachsen; —, & Exo, K-M. 2007. Climate change and migratory Festschrift Hugo Weigold, pp. 12–32. Hannover. waterbirds in the Wadden Sea. In: Reineking, B., & Exo, K-M., & Thyen, S. 2003. Ökologische Entwicklung Südbeck, P. (eds.), Seriously Declining Trends in einer wiederverlandenden Außendeichskleipütte im Migratory Waterbirds: Causes-Concerns-Consequences, westlichen Jadebusen. Vogelkundliche Berichte pp. 43–52. Wadden Sea Ecosystem No. 23. IAR, Niedersachsen 35: 143–150. Wilhelmshaven. Ezard, T. H. G., Becker, P. H., & Coulson, T. 2007. Bauch, C., Kreutzer, S., & Becker, P. H. 2010. Breeding The correlation between age, phenotypic traits and experience affects condition: blood metabolite reproductive success in Common Terns (Sterna levels over the course of incubation in a seabird. hirundo). Ecology 88: 2496–2504.

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Hüppop, K., & Hüppop, O. 2002–09. Atlas zur Lehikoinen, A., Lehikoinen, E., Rainio, K., Romano, M., Vogelberingung auf Helgoland. Teil 1–5. Vogelwarte & Sokolov, L. 2010. Climate warming, ecological 41: 161–180, 42: 285–343, 43: 217–248, 45: mismatch at arrival and population decline in 145–207, 47: 189–249. migratory birds. Proc. Roy. Soc. Lond. B. Hüppop, O., & Hüppop, K. 2003. North Atlantic doi: 10.1098/rspb.2010.1778 Oscillation and timing of spring migration in birds. Schmaljohann, H., & Dierschke, V. 2005. Optimal bird Proc. Roy. Soc. Lond. B 270: 233–240. migration and predation risk: a field experiment — & Wurm, S. 2000. Effects of winter fishery activities with Northern Wheatears Oenanthe oenanthe. J. on resting numbers, food and body condition of Anim. Ecol. 74: 131–138. large gulls Larus argentatus and L. marinus in the —, Becker, P. J. J., Karaardic, H., Liechti, F., Neaf-Daenzer, south-eastern North Sea. Marine Ecol. Prog. Series B., & Grande, C. 2010. Nocturnal exploratory 194: 241–247. flights, departure time, and direction in a migratory Hüppop, O., Dierschke, J., Exo, K-M., Fredrich, E., & songbird. J. Orn. doi: 10.1007/s10336-010-0604-y Hill, R. 2006. Bird migration studies and potential Stresemann, E. 1967. Vor- und Frühgeschichte der collision risk with offshore wind turbines. Vogelforschung auf Helgoland. J. Orn. 108: 377–429. Ibis 148: 90–109. Thyen, S., & Exo, K-M. 2005. Ökofaunistik I – Brut- und Limmer, B., & Becker, P. H. 2010. Improvement of Rastvögel. In: Flemming, B. W., & Bartholomä, A. reproductive performance with age and breeding (eds.), Untersuchungen zur ökologischen experience depends on recruitment age in a long- Entwicklung bei der Wiederverlandung einer lived seabird. Oikos 119: 500–507. Kleipütte im Außendeich bei Petersgroden Maggini, I., & Bairlein, F. 2010. Endogenous rhythms of (Jadebusen). Forschungszentrum Terramare Berichte seasonal migratory body mass changes and 14: 36–45. nocturnal restlessness in different populations of van de Pol, M., Ens, B. J., Heg, D., Brouwer, L., Krol, J., Northern Wheatear Oenanthe oenanthe. Maier, M., Exo, K-M., Oosterbeek, K., Lok, T., Eising, J. Biol. Rhythms 25: 268–276. C. M., & Koffijberg, K. 2010. Do changes in the Muñoz Cifuentes, J. 2004. Seabirds at risk? Effects of frequency, magnitude and timing of extreme environmental chemicals on reproductive success climatic events threaten the population viability of and mass growth of seabirds breeding at the coastal birds? J. Appl. Ecol. 47: 720–730. Wadden Sea in the mid 1990s, pp. 27–51. Wadden Vauk, G. 1977. Geschichte der Vogelwarte Helgoland. Sea Ecosystem No. 18, Wilhelmshaven; Niederelbe-Druck, Otterndorf. www.waddensea-secretariat.org/TMAP/wse18/ — & Moritz, V. 1979. Festschrift zum 25 jährigen wse18.html Bestehen der Inselstation Helgoland. Abhandlungen Rebke, M., Coulson, T., Becker, P. H., & Vaupel, W. 2010. aus dem Gebiet der Vogelkunde 6: 1–327. Reproductive improvement and senescence in a Weigold, I. 1986. Hugo Weigold, sein Weg zum long-lived bird. PNAS 107: 7841–7846. Naturforscher und früher Kämpfer für Naturschutz. Saino, N., Ambrosini, R., Rubolini, D., von Hardenberg, Beitr. Naturkd. Niedersachsen 39: 112–218, 277–389. J., Provenzale, A., Hüppop, K., Hüppop, O.,

Postscript With the exception of the section ‘Highlights of recent research’, this paper was published originally in German in the journal Der Falke, Vol. 75 (2010): 138–141. We thank the publisher and editors of Der Falke for permission to translate the original paper and for providing the illustrations in printable format. The English translation was conducted by David Conlin.

Franz Bairlein, Institute of Avian Research, ‘Vogelwarte Helgoland’, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany; e-mail [email protected]

Helgoland – how to visit BOX 2 A trip to Helgoland is rewarding at every season! However, the best times for watching migrants (and rarities) are between late March and mid May and in September/October, while the breeding seabirds in the cliffs and on the Düne are worth a visit mainly in May and June. May is a good compromise since all seabird species are breeding and many long-distance migrants are still on their way and stop over on the island; and the weather is normally quite settled at that time. Helgoland is a tourist site offering lots of accommodation, ranging from simple bed and breakfast outlets and a youth hostel to four-star hotels (www.helgoland.de). There is a campsite on the Düne. The island can be reached by conventional ferries from several ports (2–3 hours), high-speed catamaran (a little over an hour from Cuxhaven or four hours down the River Elbe from Hamburg) or aircraft (20 minutes). During winter there is only the ferry from Cuxhaven (four times a week, day trips only on Friday) and the flight connections. The annual meeting of the local Ornithological Working Group in October always attracts hundreds of birdwatchers (www.oag-helgoland.de).

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Appendix 1. Helgoland and rarities turn up at any time, the peak periods are Helgoland is well known for its breeding from late April to early June and from late colonies of cliff-nesting seabirds (mainly September to late October. Birdwatchers visit Fulmars Fulmarus glacialis, Northern mainly in October, so vagrancy outside this Gannets Morus bassanus, Kittiwakes Rissa tri- month is probably underrecorded. dactyla and Common Guillemots Uria aalge) Helgoland rarities have mainly an eastern, and for the impressive numbers of migrating southeastern or southern origin. Reverse passerines which occur on the island during migrants from Siberia such as Yellow-browed spring and autumn. However, most bird- P. inornatus and Pallas’s Leaf Warblers P. watchers outside Germany will know proregulus are recorded annually in autumn Helgoland mainly as an island where many and are nowadays scarce migrants with daily rarities occur. Recording rare species has a maximum counts of 24 and 10 birds, respec- long history on Helgoland: it started, as tively. Other regular vagrants from the east described above, with Heinrich Gätke in are Little Buntings E. pusilla, Richard’s A. 1843, was later continued by the Institute of richardi and Olive-backed Pipits A. hodgsoni. Avian Research ‘Vogelwarte Helgoland’ and Typical spring overshoots from the south or most recently especially by the OAG- southeast include Subalpine Warblers Sylvia Helgoland, the local birding club. cantillans, Woodchat Shrikes Lanius senator The Helgoland list stands now at 426 and Short-toed Larks Calandrella brachy- species (German taxonomy, Barthel & Helbig dactyla. During westerly gales, rare seabirds 2005) and contains about 70 ‘firsts’ for such as Sabine’s Gulls Xema sabini, Cory’s Germany. Many rare species for Germany Calonectris diomedea and Balearic Shearwa- have been recorded more or less exclusively ters may turn up, but numbers are small on Helgoland. Even in the last 20 years, 11 compared with those seen in British waters. new species have been added to the German Only a few Nearctic birds have reached the List from Helgoland: Hume’s Warbler Phyllo- island, but a Black-throated Green Warbler scopus humei (1990), Balearic Shearwater Dendroica virens is particularly notable. Puffinus mauretanicus (1992), Siberian A book on the birds of Helgoland (in Rubythroat Luscinia calliope (1995), Blyth’s German with English summaries, Dierschke Pipit Anthus godlewskii (1996), Audouin’s et al. in prep.), including an analysis of the Gull Larus audouinii (1997), Yellow-throated occurrence of rare birds as well as the Vireo Vireo flavifrons (1998), Isabelline common species, will be published in spring Wheatear Oenanthe isabellina (1999), Brown 2011, an annual journal summarises the Shrike Lanius cristatus (2001), Sykes’s observations of the preceding year (e.g. Dier- Warbler Hippolais rama (2003), Pechora Pipit schke et al. 2010) and current observations A. gustavi (2007) and Grey-necked Bunting are provided on the website of the OAG Emberiza buchanani (2009). Most recently, an Helgoland (www.oag-helgoland.de). old skin from the nineteenth century was identified as Cyprus Pied Wheatear O. References cypriaca, the only record far north of the Barthel, P. H., & Helbig, A. J. 2005. Artenliste der Vögel Deutschlands. Limicola 19: 89–111. breeding areas (Förschler et al. 2010). Dierschke, J., Dierschke, V., Schmaljohann, H., & Reasons for the large numbers of rarities Stühmer, F. 2010. Ornithologischer Jahresbericht recorded on Helgoland include its long 2009 für Helgoland. Ornithol. Jber. Helgoland 20: history of bird recording and the large 1–73. —, Dierschke, V., Hüppop, O., Hüppop, K., & Jachmann, number of birdwatchers that visit the island F. In prep. Die Vogelwelt der Insel Helgoland. regularly, but the fundamental reasons are its Förschler, M. I., Randler, C., Dierschke, J., & Bairlein, F. attraction to nocturnal migrants crossing the 2010. Morphometric diagnosability of Cyprus German Bight, the small size of the two Wheatears Oenanthe cypriaca and an unexpected occurrence on Helgoland Island. Bird Study 57: islands and the low (although increasing) 397–401. vegetation cover. Although rare birds can

Jochen Dierschke, Zedeliusstraße 31, 26384 Wilhelmshaven, Germany; e-mail [email protected]

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