Movement ecology of aerial insectivorous birds : Individual-based studies on swifts and nightjars
Many birds are predisposed to annually undertake movements over large temporal and spatial scales. They have an efficient flight machinery, demonstrate impressive capacities in storing and burning fuel, and they exhibit necessary orientation and navigational skills. Avian migrants are still limited...
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| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
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Lund University, Faculty of Science, Department of Biology
2018
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| Online Access: | https://lup.lub.lu.se/record/49d94dc4-a649-4e23-978d-d94106fceb97 https://portal.research.lu.se/files/51505512/Gabriel_N_inkl_omslag_ppen.pdf |
| Summary: | Many birds are predisposed to annually undertake movements over large temporal and spatial scales. They have an efficient flight machinery, demonstrate impressive capacities in storing and burning fuel, and they exhibit necessary orientation and navigational skills. Avian migrants are still limited in the amount of time and energy they can allocate towards their movements and need to balance migration-related costs against expenditures associated with reproduction and maintenance. Different specialisations towards a migratory life will likely evolve depending on the ecology of the bird. My work aimed to investigate the ecology of large-scale movements of three species of aerial insectivorous birds by using miniaturised technology to record individual birds´ position and activity during the non-breeding season. The common swift Apus apus and the pallid swift A. pallidus, are two highly aerial species that through their morphological and behavioural modifications are predisposed to a life in the air. Both species were documented to be air-borne throughout the non-breeding season which in the common swift results in a continuous flight for about ten months. Spending this time ranging over the African continent where large-scale weather systems generate an asynchronous seasonal landscape the swifts could potentially continuously track spatiotemporal variations in resources. However, the birds prioritised longer periods of residency briefly interrupted by shorter movement phases indicating that resource patchiness and local knowledge may be important determinants of the swifts´ movement patterns.The crepuscular and nocturnal European nightjar Caprimulgus europaeus showed in contrast to the swifts a very limited activity pattern. It is a visual hunter that mainly forages during dusk and dawn, although on moonlit nights this temporal constraint is reduced. Throughout the non-breeding season I found a clear periodic pattern in both migratory flights and foraging activities suggesting that the European nightjar may ... |
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