| 1. |
- Bonaldi, Carlotta, et al.
(author)
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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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In: Journal of Avian Biology. - 0908-8857.
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Journal article (peer-reviewed)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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| 2. |
- Debayle, Edouard J.M., et al.
(author)
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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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In: Wader Study. - : International Wader Study Group. - 2058-8410. ; 124:3, s. 186-196
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Journal article (peer-reviewed)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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| 3. |
- Lindström, Åke, et al.
(author)
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Extreme altitude changes between night and day during marathon flights of great snipes
- 2021
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In: Current Biology. - : Elsevier BV. - 0960-9822 .- 1879-0445. ; 31:15, s. 3433-3439
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Journal article (peer-reviewed)abstract
- Summary Several factors affect the flight altitude of migratory birds, such as topography, ambient temperature, wind conditions, air humidity, predation avoidance, landmark orientation, and avoiding over-heating from direct sunlight.1, 2, 3, 4, 5, 6 Recent tracking of migratory birds over long distances has shown that migrants change flight altitude more commonly and dramatically than previously thought.4, 5, 6, 7, 8 The reasons behind these altitude changes are not well understood. In their seasonal migrations between Sweden and sub-Saharan Africa, great snipes Gallinago media make non-stop flights of 4,000–7,000 km, lasting 60–90 h.9,10 Activity and air pressure data from multisensor dataloggers showed that great snipes repeatedly changed altitudes around dawn and dusk, between average cruising heights about 2,000 m (above sea level) at night and around 4,000 m during daytime. Frequency and autocorrelation analyses corroborated a conspicuous diel cycle in flight altitude. Most birds regularly flew at 6,000 m and one bird reached 8,700 m, possibly the highest altitude ever recorded for an identified migrating bird. The diel altitude changes took place independently of climate zone, topography, and habitat overflown. Ambient temperature, wind condition, and humidity have no important diel variation at the high altitudes chosen by great snipes. Instead, improved view for orientation by landmarks, predator avoidance, and not least, seeking cold altitudes at day to counteract heating from direct sunlight are the most plausible explanations for the diel altitude cycle. Together with similar recent findings for a small songbird,6 the great snipes’ altitudinal performance sheds new light on the complexity and challenges of migratory flights.
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| 4. |
- Lindström, Åke, et al.
(author)
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The migration of the great snipe Gallinago media : intriguing variations on a grand theme
- 2016
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In: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 47:3, s. 321-334
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Journal article (peer-reviewed)abstract
- The migration of the great snipe Gallinago media was previously poorly known. Three tracks in 2010 suggested a remarkable migratory behaviour including long and fast overland non-stop flights. Here we present the migration pattern of Swedish male great snipes, based on 19 individuals tracked by light-level geolocators in four different years. About half of the birds made stopover(s) in northern Europe in early autumn. They left the breeding area 15 d earlier than those which flew directly to sub-Sahara, suggesting two distinct autumn migration strategies. The autumn trans-Sahara flights were on average 5500 km long, lasted 64 h, and were flown at ground speeds of 25 m s(-1) (90 km h(-1)). The arrival in the Sahel zone of west Africa coincided with the wet season there, and the birds stayed for on average three weeks. The birds arrived at their wintering grounds around the lower stretches of the Congo River in late September and stayed for seven months. In spring the great snipes made trans-Sahara flights of similar length and speed as in autumn, but the remaining migration through eastern Europe was notably slow. All birds returned to the breeding grounds within one week around mid-May. The annual cycle was characterized by relaxed temporal synchronization between individuals during the autumn-winter period, with maximum variation at the arrival in the wintering area. Synchronization increased in spring, with minimum time variation at arrival in the breeding area. This suggests that arrival date in the breeding area is under strong stabilizing selection, while there is room for more flexibility in autumn and arrival to the wintering area. The details of the fast non-stop flights remain to be elucidated, but the identification of the main stopover and wintering areas is important for future conservation work on this red-listed bird species.
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| 5. |
- Machín, Paula, et al.
(author)
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The role of ecological and environmental conditions on the nesting success of waders in sub-Arctic Sweden
- 2019
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In: Polar Biology. - : Springer Science and Business Media LLC. - 0722-4060 .- 1432-2056. ; 42:8, s. 1571-1579
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Journal article (peer-reviewed)abstract
- Waders that breed in the sub-Arctic are one of the groups most threatened by climate change. At the same time, wader breeding success also can vary as a function of fluctuations in the numbers of predators and rodents (an alternative prey for the predators). How climate change could influence these foodweb interactions remains poorly studied. In this study, we analysed the effects of ecological (e.g. vole/lemming and predator abundance) and environmental factors (e.g. snow cover) on the breeding success of waders in sub-Arctic Lapland. We monitored more than 500 wader nests during six breeding seasons, which spanned a full rodent cycle and one year of exceptionally late snow melt. Nest predation rate, and thus wader breeding success, did not vary as a function of predator or rodent abundance. However, predation rate was exceptionally high in the year with a late snow melt. More variability in climate is expected for the future, where more precipitation and cold spring temperatures resulting in late snow melt will be more frequent, influencing the rodent and predator numbers, and therefore wader breeding success in the sub-Arctic. Snow would limit the number of open areas for nesting and hence predators would then be able to find these nests more easily. Additionally, predators might concentrate their efforts on alternative prey if snow has reduced their capacity to find other food sources. And, ultimately, changes in the rodent fluctuations could affect the final outcome of predators.
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| 6. |
- Monti, Flavio, et al.
(author)
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Migration distance affects stopover use but not travel speed : contrasting patterns between long- and short-distance migrating ospreys
- 2018
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In: Journal of Avian Biology. - : Wiley. - 0908-8857. ; 49:10
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Journal article (peer-reviewed)abstract
- The development of migratory behaviour is a continuous process which is not only determined by genes, but also moulded by individual differences based on life-history variations occurring at each ontogenetic stage. Assessing consistency and plasticity in migratory traits between long distance (LDM) and short distance migratory (SDM) populations within the same species that may express dissimilarities in the leeway of annual schedules is essential to understand the evolution and ontogeny of migratory strategies. We studied the migration strategies in autumn regarding flight speed and the use of stopovers (number and duration of stop-overs across the whole journey) at the intra-specific level, by tracking with GPS loggers the intercontinental migration of 43 adult and juvenile ospreys Pandion haliaetus from both LDM and SDM populations. LDM ospreys travelled distances five times larger than SDM ospreys, but their total migration speed was 2.4 times slower. While daily distance travelled did not differ between populations, the reduced total migration speed by LDMs was due to higher stopover use compared to SDM birds. SDM birds used more direct routes, crossing open sea at higher flight speeds, even though both populations largely benefitted from wind assistance across their journey. Across populations, adult birds travelled longer distances per day and displayed less sinuous migratory paths than juveniles, suggesting that migratory capabilities improve with age and experience of the bird. Overall, the time constraint related to total migration distance was not the main driver of the total migration speed, and other factors such as physiological needs to rest and refuel at stopover sites may play an important role. Our study underlines the importance of investigating variability in migration strategies in partially migratory species, for a better understanding of avian migratory ecology.
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| 7. |
- Strandberg, Roine, et al.
(author)
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Movements of immature European Honey Buzzards Pernis apivorus in tropical Africa
- 2012
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In: Ardea. - : Netherlands Ornithologists' Union. - 0373-2266. ; 100:2, s. 157-162
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Journal article (peer-reviewed)abstract
- Strandberg R., Hake M., Klaassen R.H.G. & Alerstam T. 2012. Movements of immature European Honey Buzzards Pernis apivorus in tropical Africa. Ardea 100: 157-162. Immature European Honey Buzzards Pernis apivorus are believed to remain in tropical Africa during the first years of their lives. We studied their movements during this period with the aid of satellite telemetry. After crossing the Sahara Desert on autumn migration, all six tracked young buzzards stopped at relatively northerly latitudes, between 9.9-13.6 degrees N. Of the five individuals that continued transmitting, four made south-directed movements, mainly in November, to areas located further south or east within latitudes 1.7-9.8 degrees N. Three young buzzards were tracked for more than three months in tropical Africa, and these individuals continued to perform extensive movements within the tropics throughout the tracking period. They travelled between 2,430 and 3,990 km (minimum distances) during 13 to 14 months, in which they visited several sites. In contrast, adult birds migrate directly to their wintering sites where they remain stationary within restricted territories. The mobile life of young Honey Buzzards during the period prior to their first northbound migration may be associated with responses to seasonal weather changes in the tropics and prospecting behaviour. These movements may also reflect intraspecific competition which might be catalyzed by forest degradation and fragmentation.
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| 8. |
- Thorup, Kasper, et al.
(author)
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Resource tracking within and across continents in long-distance bird migrants
- 2017
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In: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 3:1
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Journal article (peer-reviewed)abstract
- Migratory birds track seasonal resources across and between continents. We propose a general strategy of tracking the broad seasonal abundance of resources throughout the annual cycle in the longest-distance migrating land birds as an alternative to tracking a certain climatic niche or shorter-term resource surplus occurring, for example, during spring foliation. Whether and how this is possible for complex annual spatiotemporal schedules is not known. New tracking technology enables unprecedented spatial and temporal mapping of long-distance movement of birds. We show that three Palearctic-African species track vegetation greenness throughout their annual cycle, adjusting the timing and direction of migratory movements with seasonal changes in resource availability over Europe and Africa. Common cuckoos maximize the vegetation greenness, whereas red-backed shrikes and thrush nightingales track seasonal surplus in greenness. Our results demonstrate that the longest-distance migrants move between consecutive staging areas even within the wintering region in Africa to match seasonal variation in regional climate. End-of-century climate projections indicate that optimizing greenness would be possible but that vegetation surplus might be more difficult to track in the future.
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| 9. |
- Vardanis, Yannis, et al.
(author)
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Consistency in long-distance bird migration: Contrasting patterns in time and space for two raptors
- 2016
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In: Animal Behaviour. - : Elsevier BV. - 0003-3472. ; 113, s. 177-187
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Journal article (peer-reviewed)abstract
- As the evolutionary responses to environmental change depend on selection acting on individual differences,disentangling within- and between-individual variation becomes imperative. In animalmigration research, multiyear tracks are thus needed to estimate the individual consistency of phenotypictraits. Avian telemetry studies have recently provided the first evidence of individuality acrossspace and time in animal migration. Here, we compare repeatability patterns of routes and timing betweentwo migratory birds, the marsh harrier, Circus aeruginosus, and the osprey, Pandion haliaetus, asrecorded by satellite tracking. We found interspecific contrasts with low repeatability in timing andduration and a high repeatability in routes for ospreys, but the reverse pattern for marsh harriers. Thiswas mainly caused by (1) larger between-individual variation in routes for ospreys (broad-frontmigration) than for marsh harriers (corridor migration) and a higher degree of repeated use of the samestopover sites among ospreys, and (2) higher within-individual consistency of timing and durationamong marsh harriers, while individual ospreys were more flexible. Our findings suggest that individualityin space and time is not a shared trait complex among migrants, but may show adaptivevariation depending on the species' life history and ecology.
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| 10. |
- Williams, Heather M., et al.
(author)
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Common Cuckoo home ranges are larger in the breeding season than in the non-breeding season and in regions of sparse forest cover
- 2016
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In: Journal of Ornithology. - : Springer Science and Business Media LLC. - 2193-7192 .- 2193-7206. ; 157:2, s. 461-469
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Journal article (peer-reviewed)abstract
- Knowledge of species’ habitat requirements can be gained from studying individual variation in home range size, under the assumption that larger home ranges reflect increased resource needs or decreased habitat quality. We used satellite telemetry to delineate home ranges of South Scandinavian Common Cuckoos (Cuculus canorus) throughout their annual cycle. Annual stage (breeding or non-breeding period) and percentage of forest cover were good predictors of home range size. Average breeding season home ranges were ten times as large as those of non-breeding home ranges, suggesting strong temporal variation in the birds’ resource needs, and perhaps lower habitat quality in the breeding range compared to the African part of their annual range. Furthermore, although the Cuckoos rarely chose a home range with complete forest cover, we found a significant negative relationship between forest cover and home range area. This suggests that heterogeneous landscapes which include some dense forest cover constitute important habitat for Cuckoos, and that the continuing trend of forest loss in tropical Africa could reduce habitat quality for the Cuckoo in the non-breeding season.
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