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A daft novice question about juvenile Migrants (1 Viewer)

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Debbie1905

Well-known member
OK, I'm prepared for some eye-rolling here. Having seen juvenile Red-backed Shrike last year and juvenile Barred Warbler this week, my question is: why do we often see migrants as juveniles but less frequently as adults? What I mean is, are they bred here and the adults have flown off? Or have they got lost in Europe and flown here? Do we just see more of them because they are more tame than adults?
I'm sure it's a stupid question, but I am interested to know.
Thanks.
 
It's not daft at all Debbie. There are lots of ideas as to why there are more juveniles recorded as vagrants, and all of them sound plausible. It's probably / possibly a combination of inexperience, there tending to be more juveniles than adults in the autumn, weather, random dispersal of juveniles, after fledgling on the breeding grounds, into areas that mean it's 'easier' to go east / west than south - or none of the above. No-one is 100% certain. :-C
http://www.freewebs.com/alexlees/new uploads/Lees and Gilroy 2009 Vagrancy.pdf gives a good overview of vagrants in Britain, page 5 deals with those from the east.
 
I just read that article and it was fascinating, and exactly the kind of information I wanted, and explained very clearly. Thank you for the link, and your own comments too.
 
I'm of the opinion that many juv birds set off but only few arrive! Succumb to the water.

Adult birds have done the trip and are more experienced therefore make fewer mistakes - setting off in the right conditions and right direction....

Great reading though.
 
Debbie1905 said:
Could you tell me where might I read about that please?
Click to expand...
Henry Seebohm, The Birds of Siberia 1901, facsimile reprint in 2 volumes, To the Petchora Valley and The Yenesei, 1985 Alan Sutton ISBN 0-87052-188-8

No idea if it's still available, but worth chasing up a second-hand copy - a very good read.
 
Nutcracker said:
Henry Seebohm, The Birds of Siberia 1901, facsimile reprint in 2 volumes, To the Petchora Valley and The Yenesei, 1985 Alan Sutton ISBN 0-87052-188-8

No idea if it's still available, but worth chasing up a second-hand copy - a very good read.
Click to expand...

Agree strongly!! I go back to the 2 volume copies regularly to read about his trips...

cheers
McM
 
Debbie1905 said:
I just read that article and it was fascinating, and exactly the kind of information I wanted, and explained very clearly. Thank you for the link, and your own comments too.
Click to expand...

I might also add that juveniles of many species disperse quite widely from their natal area before setting off on migration, whereas adults often migrate directly and in fewer 'stages' to their wintering grounds; sometimes this juvenile behaviour is repeated on the migration route.

Adding to the complexity are a couple of factors - firstly, for many species, adult males and females migrate at different times, sometimes by different routes, and sometimes to different wintering grounds; secondly, the plumage of adults of many species on outward (autumn in the northern hemisphere) migration differs greatly from breeding plumage and can resemble juvenile plumage, which can add difficulty to the new birder's efforts!

Return (spring in the nh) migration is more straightforward for new birders because breeding plumages are often easier to identify, because usually it's the larger species whose immatures have intermediate plumages.
MJB
 
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