Changes in timing of autumn migration in North European songbird populations

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  • Ardea94-527

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Although studies of changes in the timing of passerine spring migration

are numerous, less is known about timing of their autumn departure.

We present phenological data on 22 species based on mist-netted birds

caught on the Baltic island of Christiansø during autumn migration

between 1976 and 1997. We used least square and quantile regression

to test for changes in departure time of the last individuals and the date

at which 5%, 50% and 95% of the season total remaining to be trapped

(corrected for catch effort). For the entire group of 22 migrants there

was no overall change in median departure (-0.0426 days year-1, P =

0.40). Testing the 12 species for which the entire migration period was

included (thus excluding many long-distance migrants), we found an

overall earlier departure (-0.18 days year-1, P = 0.007). Short-distance

migrants tended to show earlier departure, while long-distance migrants

only showed advanced departure amongst the last individuals to leave.

The magnitude of change in departure time was correlated with migration

distance, longer distance migrants showing the least change.

Overall, timing of autumn migration was more variable between species

than the unidirectional change reported in studies of spring arrival.

OriginalsprogEngelsk
TidsskriftArdea
Vol/bind94
Udgave nummer3
Sider (fra-til)527-536
ISSN0373-2266
StatusUdgivet - 2006

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