scholarly journals Consistent variation in individual migration strategies of brown skuas

2017 ◽  
Vol 578 ◽  
pp. 213-225 ◽  
Author(s):  
J Krietsch ◽  
S Hahn ◽  
M Kopp ◽  
RA Phillips ◽  
HU Peter ◽  
...  
Keyword(s):  
Consistent Variation ◽  
Migration Strategies

scholarly journals The use of nocturnal flights for barrier crossing in a diurnally migrating songbird

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Christie D. Lavallée ◽  
Saeedeh Bani Assadi ◽  
Alicia M. Korpach ◽  
James D. Ray ◽  
Jason D. Fischer ◽  
...  
Keyword(s):  
Energy Savings ◽  
Open Water ◽  
Gps Tracking ◽  
Future Research ◽  
Barrier Crossing ◽  
Migration Patterns ◽  
Migration Strategies ◽  
Diurnal Migrant ◽  
Time And Energy ◽  
High Degree

Abstract Background The migration patterns of land birds can generally be divided into those species that migrate principally during the day and those that migrate during the night. Some species may show individual plasticity in the use of day or night flight, particularly when crossing large, open-water or desert barriers. However, individual plasticity in circadian patterns of migratory flights in diurnally migrating songbirds has never been investigated. Methods We used high precision GPS tracking of a diurnal, migratory swallow, the purple martin (Progne subis), to determine whether individuals were flexible in their spring migration strategies to include some night flight, particularly at barrier crossing. Results Most (91%) of individuals made large (sometimes > 1000 km), open-water crossings of the Caribbean Sea and the Gulf of Mexico that included the use of night flight. 32% of all water crossings were initiated at night, demonstrating that night flight is not only used to complete large crossings but may confer other advantages for diurnal birds. Birds were not more likely to initiate crossings with supportive winds, however crossings were more likely when they reduced travel distances. Our results are consistent with diurnal birds using night flight to help achieve time- and energy-savings through ‘short cuts’ at barrier crossings, at times and locations when foraging opportunities are not available. Conclusions Overall, our results demonstrate the use of nocturnal flight and a high degree of individual plasticity in migration strategies on a circadian scale in a species generally considered to be a diurnal migrant. Nocturnal flights at barrier crossing may provide time and energy savings where foraging opportunities are low in an otherwise diurnal strategy. Future research should target how diel foraging and refueling strategies support nocturnal flights and barrier crossing in this and other diurnal species.

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

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

Correlation in the Ground State of He Atom

1981 ◽  
Vol 36 (3) ◽  
pp. 272-275 ◽  
Author(s):  
Subal Chandra Saha ◽  
Sankar Sengupta
Keyword(s):  
Ground State ◽  
Zero Order ◽  
Consistent Variation ◽  
Hartree Fock ◽  
Perturbation Procedure ◽  
Self Consistent ◽  
He Atom ◽  
Atomic Parameters

It is possible to reproduce the entire results of Pekeris et al. of different atomic parameters for the He atom by introducing (ll) type correlation in a self consistent variation perturbation procedure using the Hartree-Fock (HF) wavefunction as the zero-order wavefunction

Similar dispersal patterns between two closely related birds with contrasting migration strategies

2016 ◽  
Vol 58 (3) ◽  
pp. 421-427 ◽  
Author(s):  
Francesco Ceresa ◽  
Eduardo J. Belda ◽  
Juan S. Monrós
Keyword(s):  
Dispersal Patterns ◽  
Migration Strategies
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