Research output: Contribution to journal › Article › peer-review
Compensation for wind drift in the nocturnally migrating Song Thrushes in relation to altitude and wind. / Sinelschikova, Alexandra; Vorotkov, Michael; Bulyuk , Victor; Bolshakov, Casimir V.
In: Behavioural Processes, Vol. 177, 104154, 08.2020.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Compensation for wind drift in the nocturnally migrating Song Thrushes in relation to altitude and wind
AU - Sinelschikova, Alexandra
AU - Vorotkov, Michael
AU - Bulyuk , Victor
AU - Bolshakov, Casimir V.
N1 - Publisher Copyright: © 2020 Elsevier B.V.
PY - 2020/8
Y1 - 2020/8
N2 - Compensation for wind drift in relation to the side-wind velocity and altitude was investigated in Song Thrushes during autumn migration. The birds were recorded at night flying above the prominent leading line of a marine spit which coincided with the general direction of their migration. Among the large size passerine species, Song Thrushes were identified by a combination of five flight characteristics typical only of this species during particular periods of autumn. The thrushes showed different reactions to the crosswinds: complete and partial compensation for the displacement and drift. Under normal visibility, the completeness of compensation depended both on the velocity of the side-wind and altitude. The degree of compensation achieved was reduced with an increase of altitude, regardless of the wind. Under the same wind conditions, the angle of drift (the angle between the track direction and the leading line) increased with altitude, but the number of birds that compensated for drift decreased. On average, at heights below 300 m agl, the thrushes were capable of compensating completely for moderate winds; between 300 and 600 m agl compensation was partial; but above 600 m the birds drifted completely. Birds of the same species flying above the same terrain may demonstrate different reactions to the same crosswind depending on altitude. Meanwhile, flight tracks gradually deviated from the leading line with an increase in altitude, the headings of the birds got closer to the general migratory direction. It is more likely that the birds control displacement using the visual flow regulation principle by the angular velocity of the landmarks below them running aside in relation to their flight direction, which is inversely proportional to the altitude. Low flying thrushes promptly reacted to the shifting of the leading line of the spit with an average angular velocity of more than 0.8°/s perpendicular to the direction of flight and compensated completely for drift. Shifting of the leading line with an angular velocity of less than 0.4°/s, the high flying birds did not seem to notice or did not try to compensate for displacement deliberately.
AB - Compensation for wind drift in relation to the side-wind velocity and altitude was investigated in Song Thrushes during autumn migration. The birds were recorded at night flying above the prominent leading line of a marine spit which coincided with the general direction of their migration. Among the large size passerine species, Song Thrushes were identified by a combination of five flight characteristics typical only of this species during particular periods of autumn. The thrushes showed different reactions to the crosswinds: complete and partial compensation for the displacement and drift. Under normal visibility, the completeness of compensation depended both on the velocity of the side-wind and altitude. The degree of compensation achieved was reduced with an increase of altitude, regardless of the wind. Under the same wind conditions, the angle of drift (the angle between the track direction and the leading line) increased with altitude, but the number of birds that compensated for drift decreased. On average, at heights below 300 m agl, the thrushes were capable of compensating completely for moderate winds; between 300 and 600 m agl compensation was partial; but above 600 m the birds drifted completely. Birds of the same species flying above the same terrain may demonstrate different reactions to the same crosswind depending on altitude. Meanwhile, flight tracks gradually deviated from the leading line with an increase in altitude, the headings of the birds got closer to the general migratory direction. It is more likely that the birds control displacement using the visual flow regulation principle by the angular velocity of the landmarks below them running aside in relation to their flight direction, which is inversely proportional to the altitude. Low flying thrushes promptly reacted to the shifting of the leading line of the spit with an average angular velocity of more than 0.8°/s perpendicular to the direction of flight and compensated completely for drift. Shifting of the leading line with an angular velocity of less than 0.4°/s, the high flying birds did not seem to notice or did not try to compensate for displacement deliberately.
KW - drift/compensation
KW - leading line
KW - Wind
KW - altitude
KW - nocturnal migration
KW - thrushes
KW - Nocturnal migration
KW - Thrushes
KW - Leading line
KW - Altitude
KW - HEAD-DIRECTION SIGNAL
KW - RADAR
KW - BIRD MIGRATION
KW - AIRSPEED
KW - FLIGHT
KW - ORIENTATION
KW - ECOLOGY
KW - SELECTIVITY
UR - https://www.sciencedirect.com/science/article/abs/pii/S037663571930556X
UR - http://www.scopus.com/inward/record.url?scp=85085731838&partnerID=8YFLogxK
U2 - https://doi.org/10.1016/j.beproc.2020.104154
DO - https://doi.org/10.1016/j.beproc.2020.104154
M3 - Article
VL - 177
JO - Behavioural Processes
JF - Behavioural Processes
SN - 0376-6357
M1 - 104154
ER -
ID: 52850746