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Timing of nocturnal passerine migration in Arctic light conditions

Nilsson, Cecilia LU ; Bäckman, Johan LU ; Karlsson, Håkan LU and Alerstam, Thomas LU (2015) In Polar Biology 38(9). p.1453-1459
Abstract
The nocturnal migration of many passerines

starts after sunset and reaches peak intensity during the dark

hours of the night. Birds destined for high Arctic breeding

grounds encounter a special situation, as they will experience

continuous daylight when reaching the high latitudes during

the final part of spring migration. How does this affect the

pattern of nocturnal migration? We consider three alternative

hypotheses; that the period of nocturnal flight activity

may become compressed, remain unchanged or become

disorganized under Arctic light conditions. We tracked migrating

birds by radar north of the Arctic Circle (at Abisko,

68210N,... (More)
The nocturnal migration of many passerines

starts after sunset and reaches peak intensity during the dark

hours of the night. Birds destined for high Arctic breeding

grounds encounter a special situation, as they will experience

continuous daylight when reaching the high latitudes during

the final part of spring migration. How does this affect the

pattern of nocturnal migration? We consider three alternative

hypotheses; that the period of nocturnal flight activity

may become compressed, remain unchanged or become

disorganized under Arctic light conditions. We tracked migrating

birds by radar north of the Arctic Circle (at Abisko,

68210N, 18490E, in Swedish Lapland) and show that the

pattern during the night, with a migration peak around

midnight, persisted even in continuous daylight when the sun

remained above the horizon throughout the 24 h of the day.

The flight intensity peak under continuous daylight in spring

(midnight sun) was very similar to the corresponding peak in

autumn, when the migration took place under twilight conditions.

The duration of the flight period under continuous

daylight in spring lasted 8–10 h and did not seem to be

compressed. We hypothesize that the flight period under

midnight sun conditions may in fact be more protracted than

during short nights, because of release from twilight cues that

tend to synchronize initiation and termination of migratory

flights. These cues will thus capture and confine the flight

period. The results of this provisional study suggest interesting

dynamics in timing of nocturnal migratory flights

under seasonally and latitudinally changing day length

conditions, which will need detailed documentation by future

studies of migration intensity at high-latitude sites. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Polar Biology
volume
38
issue
9
pages
1453 - 1459
publisher
Springer
external identifiers
  • wos:000359188800012
  • scopus:84938742696
ISSN
1432-2056
DOI
10.1007/s00300-015-1708-x
project
CAnMove
language
English
LU publication?
yes
id
964b1c50-271c-4f2f-bdaf-b71aaeba7abb (old id 7758236)
date added to LUP
2015-08-13 09:42:17
date last changed
2017-08-06 03:24:08
@article{964b1c50-271c-4f2f-bdaf-b71aaeba7abb,
  abstract     = {The nocturnal migration of many passerines<br/><br>
starts after sunset and reaches peak intensity during the dark<br/><br>
hours of the night. Birds destined for high Arctic breeding<br/><br>
grounds encounter a special situation, as they will experience<br/><br>
continuous daylight when reaching the high latitudes during<br/><br>
the final part of spring migration. How does this affect the<br/><br>
pattern of nocturnal migration? We consider three alternative<br/><br>
hypotheses; that the period of nocturnal flight activity<br/><br>
may become compressed, remain unchanged or become<br/><br>
disorganized under Arctic light conditions. We tracked migrating<br/><br>
birds by radar north of the Arctic Circle (at Abisko,<br/><br>
68210N, 18490E, in Swedish Lapland) and show that the<br/><br>
pattern during the night, with a migration peak around<br/><br>
midnight, persisted even in continuous daylight when the sun<br/><br>
remained above the horizon throughout the 24 h of the day.<br/><br>
The flight intensity peak under continuous daylight in spring<br/><br>
(midnight sun) was very similar to the corresponding peak in<br/><br>
autumn, when the migration took place under twilight conditions.<br/><br>
The duration of the flight period under continuous<br/><br>
daylight in spring lasted 8–10 h and did not seem to be<br/><br>
compressed. We hypothesize that the flight period under<br/><br>
midnight sun conditions may in fact be more protracted than<br/><br>
during short nights, because of release from twilight cues that<br/><br>
tend to synchronize initiation and termination of migratory<br/><br>
flights. These cues will thus capture and confine the flight<br/><br>
period. The results of this provisional study suggest interesting<br/><br>
dynamics in timing of nocturnal migratory flights<br/><br>
under seasonally and latitudinally changing day length<br/><br>
conditions, which will need detailed documentation by future<br/><br>
studies of migration intensity at high-latitude sites.},
  author       = {Nilsson, Cecilia and Bäckman, Johan and Karlsson, Håkan and Alerstam, Thomas},
  issn         = {1432-2056},
  language     = {eng},
  number       = {9},
  pages        = {1453--1459},
  publisher    = {Springer},
  series       = {Polar Biology},
  title        = {Timing of nocturnal passerine migration in Arctic light conditions},
  url          = {http://dx.doi.org/10.1007/s00300-015-1708-x},
  volume       = {38},
  year         = {2015},
}