Towards a conceptual framework for explaining variation in nocturnal departure time of songbird migrants
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Most songbird migrants travel between their breeding areas and wintering grounds by a series of nocturnal flights. The exact nocturnal departure time for these flights varies considerably between individuals even of the same species. Although the basic circannual and circadian rhythms of songbirds, their adaptation to migration, and the factors influencing the birds' day-to-day departure decision are reasonably well studied, we do not understand how birds time their departures within the night. These decisions are crucial, because the nocturnal departure time defines the potential flight duration of the migratory night. The distances covered during the nocturnal migratory flights in the course of migration in turn directly affect the overall speed of migration. To understand the factors influencing the arrival of the birds in the breeding/wintering areas, we need to investigate the mechanisms that control nocturnal departure time. Here, we provide the first conceptual framework for explaining the variation commonly observed in this migratory trait. The basic schedule of nocturnal departure is likely regulated by both the circannual and circadian rhythms of the innate migration program. We postulate that the endogenously controlled schedule of nocturnal departures is modified by intrinsic and extrinsic factors. So far there is only correlative evidence that birds with a high fuel load or a considerable increase in fuel load and significant wind (flow) assistance towards their migratory goal depart early within the night. In contrast, birds migrating with little fuel and under unfavorable wind conditions show high variation in their nocturnal departure time. The latter may contain an unknown proportion of nocturnal movements not directly related to migratory flights. Excluding such movements is crucial to clearly identify the main drivers of the variation in nocturnal departure time. In general we assume that the observed variation in the nocturnal departure time is explained by individually different reactions norms of the innate migration program to both intrinsic and extrinsic factors.
|Research areas and keywords||
Subject classification (UKÄ) – MANDATORY
|Publication status||Published - 2016 Oct 17|
Niklas Larsson, Atticus Pinzon-Rodriguez, Arne Hegemann, Brianne Addison, Charlie Cornwallis, Giuseppe Bianco, INGRID SASSENHAGEN, Jerker Vinterstare, Julian Melgar, Julio Neto, Lasse Jakobsen, Mikael Ekvall, Mihaela Ilieva, Natalia Annenkova, Pallavi Chauhan, Sylvie Tesson, Yannis Vardanis, Catherine Tayleur, Emily Baird, Olle Lind, Jakob Löndahl, Tina Santl-Temkiv, Anders Hedenström, Åke Lindström, Anders Nilsson, Bengt Hansson, Dennis Hasselquist, Erik Svensson, Henrik Smith, Helena Westerdahl, Jan-Åke Nilsson, Johan Bäckman, Katarina Hedlund, Lars Råberg, Maria Ingimarsdottir, Martin Green, Maria Sandell, Martin Stjernman, Nils Kjellén, Ola Olsson, Rachel Muheim, Richard Ottvall, Staffan Bensch, Xiuhong Yang, Sara Snogerup-Linse, Heiner Linke, Mikkel Brydegaard Sorensen, Patrik Lundin, Sune Svanberg, Zuguang Guan, Ann-Sofie Albrekt, Anders Hargeby, Anders Persson, Christer Brönmark, Emma Kritzberg, Karin Rengefors, Lars-Anders Hansson, Olof Berglund, Wilhelm Granéli, Alice Nicolle, Ben Chapman, Christian Skov, Johan Ahlgren, Jakob Brodersen, Jessica von Einem, Kaj Hulthén, Kelly Gutseit, Karen Lebret, Lynn Ranåker, MATTIAS EKVALL, Mercy Lard, MIKAEL JÖNSSON, PER HALLGREN, Peter Ljungberg, Samuel Hylander, Tony Fagerberg, Therese Jephson, Tomas Johansson, Bjorn Canback, Bengt Danielsson, Christoffer Johansson, Emma Ådahl, Florian Muijres, Jörgen Ripa, Melissa Bowlin, Niclas Jonzén, Per Henningsson, Roger Härdling, Andreas Nord, Arzu Gursoy, Asghar Muhammad, Anna Nilsson, Anna Runemark, Barbara Tschirren, Cecilia Nilsson, Håkan Karlsson, Irene Pala, Juliana Dänhardt, Johan Nilsson, Jens Rydell, Jonas Waldenström, Keith Larson, Kristina Karlsson, Kristin Scherman, Mikael Åkesson, Martin Andersson, Maja Tarka, Maren Wellenreuther, Max Lundberg, Miriam Liedvogel, Maj Rundlöf, Martin Wintersparv Stervander, Machteld Verzijden, Olof Hellgren, Raymond Klaassen, Roine Strandberg, Susanne Åkesson, SANDRA SKÖLD CHIRIAC, Sophia Engel, Sissel Sjöberg, Sara Naurin, Thomas Alerstam, Tom J Evans, Torbjörn von Schantz, Ulf Ottosson, Marie Dacke & Helena Osvath
2008/06/01 → 2018/12/31