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- Alerstam, Thomas, et al.
(författare)
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Convergent patterns of long-distance nocturnal migration in noctuid moths and passerine birds.
- 2011
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Ingår i: Royal Society of London. Proceedings B. Biological Sciences. - : The Royal Society. - 1471-2954. ; 278, s. 3074-3080
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Tidskriftsartikel (refereegranskat)abstract
- Vast numbers of insects and passerines achieve long-distance migrations between summer and winter locations by undertaking high-altitude nocturnal flights. Insects such as noctuid moths fly relatively slowly in relation to the surrounding air, with airspeeds approximately one-third of that of passerines. Thus, it has been widely assumed that windborne insect migrants will have comparatively little control over their migration speed and direction compared with migrant birds. We used radar to carry out the first comparative analyses of the flight behaviour and migratory strategies of insects and birds under nearly equivalent natural conditions. Contrary to expectations, noctuid moths attained almost identical ground speeds and travel directions compared with passerines, despite their very different flight powers and sensory capacities. Moths achieved fast travel speeds in seasonally appropriate migration directions by exploiting favourably directed winds and selecting flight altitudes that coincided with the fastest air streams. By contrast, passerines were less selective of wind conditions, relying on self-powered flight in their seasonally preferred direction, often with little or no tailwind assistance. Our results demonstrate that noctuid moths and passerines show contrasting risk-prone and risk-averse migratory strategies in relation to wind. Comparative studies of the flight behaviours of distantly related taxa are critically important for understanding the evolution of animal migration strategies.
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| 2. |
- Bonaldi, Carlotta, et al.
(författare)
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Recurrence, fidelity and proximity to previously visited sites throughout the annual cycle in a trans-Saharan migrant, the common cuckoo
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Ingår i: Journal of Avian Biology. - 0908-8857.
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Tidskriftsartikel (refereegranskat)abstract
- Most migratory birds return every year to the same breeding sites and some species show a similarly high fidelity to wintering grounds as well. Fidelity to stopover sites during migration has been much less studied and is usually found to be lower. Here, we investigate site fidelity and distance to previously visited sites throughout the annual cycle in the common cuckoo, a nocturnal trans-Saharan migrant, based on satellite-tracking data from repeated annual migrations of thirteen adult males. All birds (100%) returned to the same breeding grounds, with a median shortest distance of only 1 km from the locations in previous year. This was in strong contrast to a much lower and much less precise site fidelity at non-breeding sites during the annual cycle: In only 18% of the possible cases in all non-breeding regions combined, did the cuckoos return to within 50 km of a previously visited non-breeding site, with no significant differences among the main staging regions (Europe in autumn, Sahel in autumn, wintering in Central Africa, West Africa in spring, Europe in spring). The shortest distance to a previously visited non-breeding site differed among the staging regions with median shortest distances for the longest stopovers of 131 km [2;1223] (median [min;max]) in Europe, 207 km [1;2222] in Sahel in autumn and 110 km [0;628] in Central Africa. The distance to a previously visited staging site decreased with the time spent at the stopover in a previous year. Understanding the drivers of recurrence and site selection in migratory birds are important for guiding conservation efforts in this group but further studies are needed to establish whether the patterns observed in cuckoos are general among terrestrial migrants with continuous distribution of habitat.
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| 3. |
- Chapman, Jason W., et al.
(författare)
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Animal Orientation Strategies for Movement in Flows
- 2011
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Ingår i: Current Biology. - : Elsevier BV. - 1879-0445 .- 0960-9822. ; 21:20, s. 861-870
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Forskningsöversikt (refereegranskat)abstract
- For organisms that fly or swim, movement results from the combined effects of the moving medium - air or water - and the organism's own locomotion. For larger organisms, propulsion contributes significantly to progress but the flow usually still provides significant opposition or assistance, or produces lateral displacement ('drift'). Animals show a range of responses to flows, depending on the direction of the flow relative to their preferred direction, the speed of the flow relative to their own self-propelled speed, the incidence of flows in different directions and the proportion of the journey remaining. We here present a classification of responses based on the direction of the resulting movement relative to flow and preferred direction, which is applicable to a range of taxa and environments. The responses adopted in particular circumstances are related to the organisms' locomotory and sensory capacities and the environmental cues available. Advances in biologging technologies and particle tracking models are now providing a wealth of data, which often demonstrate a striking level of convergence in the strategies that very different animals living in very different environments employ when moving in a flow.
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| 4. |
- Debayle, Edouard J.M., et al.
(författare)
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Great Snipes in sub-Saharan Africa : Seasonal patterns of abundance, moult and body mass in relation to age and sex
- 2017
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Ingår i: Wader Study. - : International Wader Study Group. - 2058-8410. ; 124:3, s. 186-196
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Tidskriftsartikel (refereegranskat)abstract
- Great Snipes Gallinago media spend about eight months per year in sub-Saharan Africa, but most aspects of their non-breeding ecology are poorly known. We analysed the seasonal pattern of appearance, flight feather moult (primaries and secondaries), and body mass in relation to age and sex, based on 3,247 birds collected by hunters in 1990–2000 in Benin, Gabon, Cameroon and the Democratic Republic of Congo. Adult males arrived in Africa from mid-August with a suspended flight feather moult. Adult females on average arrived somewhat later, and were about one month behind in the progress of flight feather moult. The adults of both sexes resumed moult immediately upon arrival. Flight feather moult was generally completed by the end of November in males, and end of December in females. Juvenile Great Snipes arrived later than adults and did not moult their flight feathers. The temporal pattern of occurrence at the different study sites suggests a general relocation of snipes from West Africa to Central Africa in October-December. Body masses did not differ between age groups and were generally low from August to February (155–170 g in males and 165–185 g in females). Males apparently departed northwards from late March to late April, and the females about two weeks later. Prior to departure, body mass increased on average with about 50 g (in both sexes), suggesting a departure fuel load of 31–33% above lean body mass. In periods of high and stable mass increase, fuel was deposited at rates of about 0.8–1.3 g/d (or 0.5–0.8% of lean body mass/d). The heaviest males and females had a total body mass of 242 and 250 g, respectively. This kind of traditional natural history data forms an important complement to the new type of data emerging from modern tracking techniques.
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| 5. |
- Dominoni, Davide M., et al.
(författare)
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Methods in field chronobiology
- 2017
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Ingår i: Philosophical Transactions of the Royal Society B: Biological Sciences. - : The Royal Society. - 1471-2970 .- 0962-8436. ; 372:1734
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Forskningsöversikt (refereegranskat)abstract
- Chronobiological research has seen a continuous development of novel approaches and techniques to measure rhythmicity at different levels of biological organization from locomotor activity (e.g. migratory restlessness) to physiology (e.g. temperature and hormone rhythms, and relatively recently also in genes, proteins and metabolites). However, the methodological advancements in this field have been mostly and sometimes exclusively used only in indoor laboratory settings. In parallel, there has been an unprecedented and rapid improvement in our ability to track animals and their behaviour in the wild. However, while the spatial analysis of tracking data is widespread, its temporal aspect is largely unexplored. Here, we review the tools that are available or have potential to record rhythms in thewild animals with emphasis on currently overlooked approaches and monitoring systems. We then demonstrate, in three question-driven case studies, how the integration of traditional and newer approaches can help answer novel chronobiological questions in free-living animals. Finally, we highlight unresolved issues in field chronobiology that may benefit from technological development in the future. As most of the studies in the field are descriptive, the future challenge lies in applying the diverse technologies to experimental set-ups in the wild.
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| 9. |
- Hedenström, Anders, et al.
(författare)
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Migration of the Little Ringed Plover Charadrius dubius breeding in South Sweden tracked by geolocators
- 2013
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Ingår i: Bird Study. - : Informa UK Limited. - 0006-3657 .- 1944-6705. ; 60:4, s. 466-474
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Tidskriftsartikel (refereegranskat)abstract
- Capsule Little Ringed Plovers breeding in South Sweden migrate towards the southeast in the autumn, via the Middle East, to winter in Saharan and sub-Saharan locations or in India, while the spring migration is more directly towards the north.Aims To study the migration routes and wintering area of Little Ringed Plovers (Charadrius dubius) breeding in South Sweden, and to investigate the migration strategy and speed for this little studied shorebird.Methods We use light-level geolocators to track the year-round movements of Little Ringed Plovers breeding in South Sweden.Results Autumn migration proceeded towards the southeast, in three birds via lengthy stopovers in the Middle East, followed by movements towards the west and southwest to final winter destinations in Africa, while one male made a long stopover in northwestern Iran before migrating to India. The birds wintering in Africa probably stayed at freshwater locations in the Sahara or just south or north of the Sahara. Spring migration was more directly back to the breeding area. Overall migration speeds were similar during autumn and spring migration at about 189 and 209km/day, respectively. The migration was carried out mainly as many short flights between stopovers. In particular, autumn migration was longer than the direct distance between breeding and wintering sites.Conclusions This study shows that the geolocator method can successfully be used with relatively small (40g) shorebirds. We found that a local population of Little Ringed Plover may have widely differing wintering sites (low connectivity), from sub-Saharan Africa to the Indian subcontinent. The migration strategy of the Little Ringed Plover, with multiple short flights, deviates from that of many other long-distance migrating shorebirds that, instead, make one or a few long flights.
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| 10. |
- Klaassen, Raymond, et al.
(författare)
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Flexibility in daily travel routines causes regional variation in bird migration speed
- 2008
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Ingår i: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 1432-0762 .- 0340-5443. ; 62:9, s. 1427-1432
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Tidskriftsartikel (refereegranskat)abstract
- We used novel Global Positioning System-based satellite telemetry to reconstruct daily time budgets on travelling days of a long-distance migrant, the Osprey Pandion haliaetus, to reveal how landscape affects migratory performance. We compared daily travel routines between the Ospreys' passage of Europe and the Sahara. In Europe, where feeding habitat is abundant, Ospreys fed both before-after flights and during interruptions, thus, combining migration with foraging. This resulted in a 2.7-h shorter daily flight period in Europe than in the Sahara. A calculated energy budget indicated that a 'fly-and-forage migration strategy' is favourable in Europe because associated benefits (energy intake) more than outweigh costs (reduced flight time). The much shorter flight time in Europe was the main explanation why Ospreys covered on average 78 km less distance on a travelling day in Europe than in the Sahara. In addition, there were regional differences in hourly flight speeds that are most probably the result of variation in thermal soaring conditions. We conclude that landscape properties have a profound effect on migration through regional variation in daily routines.
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