Common tern colony Banter See

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Common tern colony on Lake Banter in Wilhelmshaven
Aerial view of the common tern colony
Marked common terns sit on a resting place equipped with an antenna and scales.
Soaked bug in an artificial egg.

The common tern colony Banter See is located on Banter See in Wilhelmshaven .

For the common tern colony there is a long-term research project of the institute for bird research "Vogelwarte Helgoland" on the biology of the common tern ( Sterna hirundo ), a small, long-lived sea bird species. Common terns have been breeding on the north side of Lake Banter since 1984 and have been closely observed and studied ever since.

Location

The site consists of six artificial concrete islands, each surrounded by a concrete wall, which were formerly part of the submarine harbor in Lake Banter. The breeding site is designated as a natural monument of the city of Wilhelmshaven. Originally the colony was breeding in the north port, but had to be relocated due to renovations. This was achieved by luring the birds with sound mockups .

colony

From the initial 90 breeding pairs the colony grew to 530 breeding pairs in 2005, but shrank due to reduced breeding success, lower young bird survival rates and delayed first breeding to 430 pairs in 2011, due to poor feeding conditions. The breeding success is very variable and strongly dependent on the nutritional situation in the Wadden Sea , where the common terns search for young fish of herring , sprat and smelt . The predation rate is low due to protective measures against rats and other terrestrial predators. A few years ago, however, there were heavy losses from owls. The colony is also protected from flooding.

Methods

Since 1980 all chicks have been ringed to determine the breeding success. Since 1992, more than 5,000 young birds and also some adult birds have been marked with transponders . Each season, the transponder-marked animals are automatically detected with an antenna system without having to be caught. This happens at seats on the walls (non-breeders and breeding birds) as well as at the nests (breeding birds). There are also scales built into many of the seats on which the birds can be weighed automatically. With this system, arrival dates, body weights, pair partners and breeding success of hundreds of birds can be documented year after year. In this way, the life stories of the common terns, which are true to their location, can be traced and important information for the population ecology of long-lived birds can be obtained.

Many traits change with the age of the common tern, and they get better and better as they age. So they postpone the arrival and laying dates and increase the breeding success up to the age of about 15 years before they show senescence in old age . The common terns, which reach a very old age, have the highest life breeding success.

To investigate the physiology of the animals, blood samples are also taken without catching the adult birds. The blood collection without trapping prevents the stress in the animals, the blood levels for. B. could change through increased stress hormones . This is achieved through the use of Mexican predatory bugs ( Dipetalogaster maxima ) , which are hungry and placed in a hollow artificial egg and placed in the nest of the breeding bird. The bug can suck blood from the breeding bird through holes in the egg shell, which is then used to investigate hormones , other blood parameters and genetics .

Web links

Commons : Common Tern Colony Banter See  - Collection of images, videos and audio files

Individual evidence

  1. ↑ PH Becker: Common terns (Sterna hirundo) in Wilhelmshaven . Oldenburger Jahrbuch 96, Isensee Verlag, Oldenburg 1996
  2. ↑ KL Szostek, PH Becker: Terns in trouble: demographic Consequences of low breeding success and recruitment on a common tern population in the German Wadden Sea. Journal of Ornithology 153: 313-326, 2012
  3. ^ A. Dänhardt, P. Becker: Herring and Sprat Abundance Indices Predict Chick Growth and Reproductive Performance of Common Terns Breeding in the Wadden Sea . Ecosystems 14: 791-803, 2011
  4. ↑ PH Becker, H. Wendeln: A New Application for Transponders in Population Ecology of the Common Tern. The Condor 99: 534-538, 1997
  5. ^ PH Becker, THG Ezard, J.-D. Ludwigs, H. Sauer-Gürth, M. Wink: Population sex ratio shift from fledging to recruitment: consequences for demography in a philopatric seabird. Oikos 117: 60-68, 2008
  6. ^ THG Ezard, PH Becker and T. Coulson: Correlations between age, phenotype, and individual contribution to population growth in common terns . Ecology 88: 2496-2504, 2007
  7. ^ PH Becker, T. Dittmann, J.-D. Ludwigs, B. Limmer, SC Ludwig, C. Bauch, A. Braasch, H. Wendeln: Timing of initial arrival at the breeding site predicts age at first reproduction in a long-lived migratory bird . PNAS 105: 12349-12352, 2008
  8. ↑ M. Rebke, T. Coulson, PH Becker, JW Vaupel: Reproductive improvement and senescence in a long-lived bird . PNAS: 1-6, 2010
  9. ↑ C. Bauch, S. Kreutzer, P. Becker: Breeding experience affects condition: blood metabolite levels over the course of incubation in a seabird. Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology 180: 835-845, 2010
  10. ^ J. Riechert, O. Chastel, PH Becker: Why do experienced birds reproduce better? Possible endocrine mechanisms in a long-lived seabird, the common tern . General and Comparative Endocrinology 178: 391-399, 2012

Coordinates: 53 ° 30 ′ 39.6 "  N , 8 ° 6 ′ 18.8"  E