scholarly journals Alternate non-stop migration strategies of pied flycatchers to cross the Sahara desert

Biology Letters â—½  
2016 â—½  
Vol 12 (4) â—½  
pp. 20151060 â—½  
Author(s):  
Janne Ouwehand â—½  
Christiaan Both
Keyword(s):  
Frequent Occurrence â—½  
Autumn Migration â—½  
Sahara Desert â—½  
Migration Strategy â—½  
Intermittent Flight â—½  
Migration Strategies

Each year more than two billion songbirds cross the Sahara, but how they perform this formidable task is largely unknown. Using geolocation tracks from 27 pied flycatchers, a nocturnally migrating passerine, we show that most birds made diurnal flights in both autumn and spring. These diurnal flights were estimated to be part of non-stop flights of mostly 40–60 h. In spring, birds flew across the Sahara, while autumn migration probably circumpassed part of the desert, through a long oversea flight. Our data contradict claims that passerines cross the Sahara by intermittent flight and daytime resting. The frequent occurrence of long non-stop flights to cross the desert shows migrants' physiological abilities and poses the question why this would not be the general migration strategy to cross the Sahara.

scholarly journals Seasonal differences in migration strategies of Red Kites (Milvus milvus) wintering in Spain

2021 â—½  
Author(s):  
Jorge García-Macía â—½  
Javier Vidal-Mateo â—½  
Javier De La Puente â—½  
Ana Bermejo â—½  
Rainer Raab â—½  
...  
Keyword(s):  
Spring Migration â—½  
Great Variability â—½  
Autumn Migration â—½  
Seasonal Differences â—½  
North Eastern â—½  
Wintering Areas â—½  
Satellite Transmitters â—½  
Migration Strategies â—½  
Migratory Movements â—½  
Milvus Milvus

AbstractRed Kite shows a great variability in its migration strategies: most individuals in north-eastern Europe are migrants, but there is also a growing number of sedentary individuals. Here, we tagged 49 Red Kites wintering in Spain with GPS/satellite transmitters between 2013 and 2020 to study the autumn and spring migration between the breeding or summering areas in Central Europe and the wintering quarters in Spain. In first place, differences between immatures and adults were found for spring migration. Adults began the spring migration towards the northeast in February–March while the immature individuals began to migrate significantly later and showing a wider date range (February-June). Adults also takes significantly less days to arrive at their destinations (12 ± 5 days) and cover more distance per day (134.2 ± 37.1 km/day) than immatures (19 ± 11 days and 98.9 ± 21.2 km/day). In second place, we also found differences between spring and autumn migration (excluding immatures). Spring migrations were clearly faster and with less stopovers days than autumn migrations. Autumn migration began between mid-October and late November and two different behaviours were observed: most birds made a quick migration direct to the wintering areas with only some days of stopovers, but others prolonged the migration with long stops along the route. These results highlight a great variation in the migratory movements of Red Kite, not only according to age but also between individuals and seasons.

scholarly journals Autumn migration strategy of juvenile great reed warblers Acrocephalus arundinaceus on the eastern European flyway: a spatiotemporal pattern of accumulation and utilisation of energy stores

2020 â—½  
Vol 87 (1) â—½  
pp. 537-551
Author(s):  
K. Stępniewska â—½  
A. Ożarowska â—½  
P. Busse â—½  
R. Bobrek â—½  
P. Zehtindjiev â—½  
...  
Keyword(s):  
Autumn Migration â—½  
Spatiotemporal Pattern â—½  
Eastern European â—½  
Acrocephalus Arundinaceus â—½  
Migration Strategy â—½  
Energy Stores

scholarly journals Evolution of moult-migration is directly linked to aridity of the breeding grounds in North American passerines

Biology Letters â—½  
2020 â—½  
Vol 16 (6) â—½  
pp. 20200155
Author(s):  
Claudie Pageau â—½  
Christopher M. Tonra â—½  
Mateen Shaikh â—½  
Nancy J. Flood â—½  
Matthew W. Reudink
Keyword(s):  
North American â—½  
Vegetation Index â—½  
Normalized Difference Vegetation Index â—½  
Autumn Migration â—½  
Western North America â—½  
Migration Distance â—½  
Migration Strategy â—½  
Breeding Grounds â—½  
Breeding Migration â—½  
Moult Migration

To avoid energy allocation conflicts, birds generally separate breeding, migration and moult during the annual cycle. North American passerines typically moult on the breeding grounds prior to autumn migration. However, some have evolved a moult-migration strategy in which they delay moult until stopping over during autumn migration. Rohwer et al . (2005) proposed the ‘push–pull hypothesis' as an explanation for the evolution of this moult strategy, but it has not been empirically tested. Poor conditions on the breeding grounds at the end of the summer would push birds to depart prior to moult, while productive stopover locations would pull them. We tested for a relationship between moult-migration and breeding grounds aridity as measured by the normalized difference vegetation index. Our results strongly support the ‘push' aspect of the push–pull hypothesis and indicate that arid breeding grounds, primarily in western North America, would drive species to evolve stopover moult-migration, although this relationship may depend upon migration distance.

Autumn Migration Strategies of Reed and Sedge Warblers

Ornis Scandinavica â—½  
10.2307/3675898 â—½  
1981 â—½  
Vol 12 (1) â—½  
pp. 1 â—½  
Author(s):  
C. J. Bibby â—½  
R. E. Green
Keyword(s):  
Autumn Migration â—½  
Migration Strategies

scholarly journals Autumn Migration Of The Thrush Nightingale (Luscinia Luscinia) In Northern Hungary

Ring â—½  
2012 â—½  
Vol 34 (1) â—½  
pp. 23-36 â—½  
Author(s):  
Dávid Kováts
Keyword(s):  
Arrival Time â—½  
Wing Length â—½  
Age Groups â—½  
Autumn Migration â—½  
Stopover Site â—½  
Migration Strategies â—½  
Median Date â—½  
The Mean â—½  
Fat Score â—½  
Thrush Nightingale

Abstract Kováts D. 2012. Autumn migration of the Thrush Nightingale (Luscinia luscinia) in northernHungary. Ring 34: 23-36. The autumn migration of the Thrush Nightingale was studied in Szalonna in northern Hungary in 1989-2010. Birds were mist-netted, ringed, aged, measured, weighed and fat scored. In total, 193 Thrush Nightingales were ringed during 22 years. Relations between arrival time and biometrical measurements were determined. Within the study period (6 August - 26 September) the migration curve was bimodal showing maximum on 22 August and 27 August. Immature birds arrived significantly earlier with lower body mass and shorter wing length and had more pointed wings in the first half of their passage. The distribution of fat score classes did not differ significantly between the early and late periods of the most intensive migration, although the mean of the deposited fat was the lowest during the peak of migration. Fat reserve distribution was bimodal in autumn suggesting that Thrush Nightingales probably start their journey from different breeding ranges (populations) or follow still undiscovered migration strategies of sex/age groups. The low proportion of recaptures proved that the area was not used as a stopover site or premigratory fattening area. Within 22 years of study, the median date of autumn migration of Thrush Nightingales shifted 7.9 days earlier, probably due to current climate change.

scholarly journals Songbird migration across the Sahara: the non-stop hypothesis rejected!

2006 â—½  
Vol 274 (1610) â—½  
pp. 735-739 â—½  
Author(s):  
Heiko Schmaljohann â—½  
Felix Liechti â—½  
Bruno Bruderer
Keyword(s):  
Energy Loss â—½  
High Temperatures â—½  
Bird Migration â—½  
Autumn Migration â—½  
Night Time â—½  
Western Sahara â—½  
The World â—½  
Intermittent Flight â—½  
Western Palaearctic â—½  
Songbird Migration

Billions of songbirds breeding in the Western Palaearctic cross the largest desert of the world, the Sahara, twice a year. While crossing Europe, the vast majority use an intermittent flight strategy, i.e. fly at night and rest or feed during the day. However, it was long assumed that they overcome the Sahara in a 40 h non-stop flight. In this study, we observed bird migration with radar in the plain sand desert of the Western Sahara (Mauritania) during autumn and spring migration and revealed a clear prevalence of intermittent migration. Massive departures of songbirds just after sunset independent of site and season suggests strongly that songbirds spent the day in the plain desert. Thus, most songbirds cross the Sahara predominately by the intermittent flight strategy. Autumn migration took place mainly at low altitudes with high temperatures, its density decreased abruptly before sunrise, followed by very little daytime migration. Migration was highly restricted to night-time and matched perfectly the intermittent flight strategy. However, in spring, when migratory flights occurred at much higher altitudes than in autumn, in cool air, about 17% of the songbird migration occurred during the day. This suggests that flying in high temperatures and turbulent air, as is the case in autumn, may lead to an increase in water and/or energy loss and may prevent songbirds from prolonged flights into the day.

scholarly journals Genetic determination of migration strategies in large soaring birds: evidence from hybrid eagles

2018 â—½  
Vol 285 (1884) â—½  
pp. 20180855 â—½  
Author(s):  
Ülo Väli â—½  
Paweł Mirski â—½  
Urmas Sellis â—½  
Mindaugas Dagys â—½  
Grzegorz Maciorowski
Keyword(s):  
Bird Species â—½  
Migration Strategy â—½  
Genetic Determination â—½  
Timing Of Migration â—½  
Habitat Suitability Modelling â—½  
Migration Strategies â—½  
Soaring Birds â—½  
Genetically Determined â—½  
Migratory Movements

The relative contributions of genetic and social factors in shaping the living world are a crucial question in ecology. The annual migration of birds to their wintering grounds and back provides significant knowledge in this field of research. Migratory movements are predominantly genetically determined in passerine birds, while in large soaring birds, it is presumed that social (cultural) factors play the largest role. In this study, we show that genetic factors in soaring birds are more important than previously assumed. We used global positioning system (GPS)-telemetry to compare the autumn journeys and wintering ranges of two closely related large raptorial bird species, the greater spotted eagle Clanga clanga and the lesser spotted eagle Clanga pomarina , and hybrids between them. The timing of migration in hybrids was similar to that of one parental species, but the wintering distributions and home range sizes were similar to those of the other. Tracking data were supported by habitat suitability modelling, based on GPS fixes and ring recoveries. These results suggest a strong genetic influence on migration strategy via a trait-dependent dominance effect, although we cannot rule out the contribution of social interactions.

Clustering-Based Cloud Migration Strategies

2018 â—½  
Vol 22 (3) â—½  
pp. 295-305
Author(s):  
Mubeen Aslam â—½  
â—½  
Lukman bin AB Rahim â—½  
Junzo Watada â—½  
Manzoor Hashmani
Keyword(s):  
Selection Process â—½  
Cloud Service â—½  
Suitable Model â—½  
Migration Strategy â—½  
Platform As A Service â—½  
Cloud Migration â—½  
Migration Strategies â—½  
Logic Approach â—½  
Realization Factors â—½  
Legacy Applications

The k-means algorithm of the partitioning clustering method is used to analyze cloud migration strategies in this study. The extent of assistance required to be provided to organizations while working on migration strategies was investigated for each cloud service model and concrete clusters were formed. This investigation is intended to aid cloud consumers in selecting their required cloud migration strategy. It is not easy for businessmen to select the most appropriate cloud migration strategy, and therefore, we proposed a suitable model to solve this problem. This model comprises a web of migration strategies, which provides an unambiguous visualization of the selected migration strategy. The cloud migration strategy targets the technical aspects linked with cloud facilities and measures the critical realization factors for cloud acceptance. Based on similar features, a correlation among the migration strategies is suggested, and three main clusters are formed accordingly. This helps to link the cloud migration strategies across the cloud service models (software as a service, platform as a service, and infrastructure as a service). This correlation was justified using the digital logic approach. This study is useful for the academia and industry as the proposed migration strategy selection process aids cloud consumers in efficiently selecting a cloud migration strategy for their legacy applications.

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