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Extensive fuelling in great reed warblers following the trans-Sahara crossing in spring
Stockholm University, Faculty of Science, Department of Zoology, Ethology.
Stockholm University, Faculty of Science, Department of Zoology, Ethology.ORCID iD: 0000-0002-9741-4431
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Migratory birds wintering in Africa face the challenge of passing the Sahara desert with little opportunities to forage. During spring migration birds thus arrive in the Mediterranean area after crossing the desert with very low energy reserves. Since early arrival to the breeding grounds often is of importance to maximize reproductive success, finding stopover sites with good refuelling possibilities after the Saharan passage is of utmost importance. Here we report on extensive fuelling in the great reed warbler, Acrocephalus arundinaceus, on the south coast of Crete in spring, the first land that they encounter after crossing the Sahara desert and the Mediterranean Sea in this area. Birds were trapped with mist nets at a river mouth, individually ringed and information about body mass, wing length, muscle score and fat score were recorded. Due to an exceptional high recapture rate at the trapping site (45%), we were able to calculate minimum stopover time and fuel deposition rates in 25 individual great reed warblers during one spring season. The large proportion of trapped great reed warbler compared to other species and the large number of recaptures suggests that great reed warbler actively choose this area for stopover. The relatively long stopover period at the site, the high fuel deposition rate (1 g day-1) and the large body mass increase show that great reed warblers at this site regularly deposit a much larger fuel load than needed for one continued flight stage to the north. It was also shown that birds with lower body mass at first capture had a higher fuel deposition rate than birds with higher body mass. This indicates that individuals are able to adjust their food intake in relation to energy reserves.

National Category
Behavioral Sciences Biology
Research subject
Ethology
Identifiers
URN: urn:nbn:se:su:diva-126970OAI: oai:DiVA.org:su-126970DiVA: diva2:904548
Available from: 2016-02-18 Created: 2016-02-18 Last updated: 2016-02-23Bibliographically approved
In thesis
1. Migratory routes and stopover behaviour in avian migration
Open this publication in new window or tab >>Migratory routes and stopover behaviour in avian migration
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Migratory birds, some small and light weight as matchboxes, engage in seasonal inter-continental journeys in order to take advantage of the long summer days and abundance of food at northern latitudes to breed and raise their young, and then escape the harsh winters by migrating to lower latitudes. This thesis deals with two important aspects of migration, the routes taken during migration and the birds’ behaviour at stopovers. The migratory routes are for many species unknown, whole or in part, and this is especially true for species that migrate nocturnally. At stopovers birds replenish fuel reserves that powers migratory flight, and studying how birds utilise stopovers is important in order to understand how migration is organised. In this thesis I have used modern tracking technology to study both continental wide movements of thrush nightingales (Luscinia luscinia) and common rosefinches (Carpodacus erythrinus) using small light-level geolocators, and smaller scale movements at a single stopover site of garden warblers (Sylvia borin) using miniature radio-transmitters. I have also studied the fuelling behaviour of garden warblers during autumn migration in the field and in the lab, and great reed warblers (Acrocephalus arundinaceus) at a stopover site on Crete during spring migration after the Sahara crossing. The thesis discusses the significance of several aspects of migration shown by the birds that would have been very difficult to detect without the aid of modern tracking technology, such as loop migration, prolonged stops during migration, multiple wintering sites, and nocturnal relocations at stopover sites. Studies carried out at stopover sites also show that garden warblers and great reed warblers can attain large fuel loads even at sites where they have no barrier to cross and this might be a result of good foraging conditions. The thesis also highlights the importance of combining different techniques when studying stopover behaviour to get reliable estimates on stopover durations and fuel deposition rates as well as the importance of choosing sites preferred by birds when planning stopover studies.

Place, publisher, year, edition, pages
Stockholm: Department of Zoology, Stockholm University, 2016. 49 p.
Keyword
Bird migration, migration routes, stopover, geolocator, radio telemetry, tracking, fuel deposition
National Category
Behavioral Sciences Biology
Research subject
Ethology
Identifiers
urn:nbn:se:su:diva-126975 (URN)978-91-7649-333-5 (ISBN)
Public defence
2016-04-08, Vivi Täckholmsalen (Q-salen), NPQ-huset, Svante Arrhenius väg 20, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Manuscript. Paper 5: Manuscript.

Available from: 2016-03-18 Created: 2016-02-18 Last updated: 2016-03-18Bibliographically approved

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