Ringers are well aware that unusual bird movements or bird moult can hint at something yet to be discovered. While ringing in his Nottinghamshire garden Adrian Blackburn has caught over 700 Swallows this year, with most of them being juveniles but with some adults also. One of these was wearing a Spanish ring but more interestingly one bird seemed to be both adult and juvenile at first glance.
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| Juvenile Swallow |
Unfortunately this Swallow was unringed (so origin unknown) but the most remarkable thing about this bird is that it was a juvenile that was going through its main moult into adult plumage, and replacing its wing feathers! British Swallows normally do this in Africa so a bird moulting in Nottinghamshire is was very unusual. The 'old' juvenile wing and tail feathers were much browner compared to the new growing feathers and this hints that this bird has been in a sunny location so unlikely to be in Nottinghamshire.
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| Swallow with older brown feathers and new blue feathers |
Could this bird have hatched in Iberia and moved North to the UK instead of South to Africa (similar to reverse migration) or did this bird hatch in the far North and started moult before reaching its wintering grounds? Hopefully this bird will be captured again by a ringer further on in its journey and start to answer some of these questions.
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| Swallow tails with older feathers but replaced blue rump feathers |
Thanks to Adrian Blackburn for letting us know and for the photos.
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Dear fellows
ReplyDeleteHere in Spain several Hirundo rustica, Riparia riparia and Delichon urbica (both juveniles and adults) start their main moult before the migration; then they stop the moult and finish it in Africa...
You can see many examples in our blog (http://grupoaegithalos.blogspot.com.es/search/label/anillamiento%20de%20golondrinas)
So the swallow that you mean might be a Spanish swallow which travelled to the north... who knows?... interesting!
Congratulations for your work!
Also in Italy (our ringing station is in Natural Reserve of Fondo Toce - Lake Maggiore, Piedmont) is not unusual to find Hirundo rustica with suspended moult.
ReplyDeleteNormaly are adults with one or two inner primary feathers new, but sometimes it's possible to find juveniles.
But the swallow in the photos it's a very strange thing with so many feathers new... Interesting!
I add an off-topic note: we are ringing swallows on roost since 2001 and in the last three years we have a drastic decrease in the number of birds (from several ten thousands to few hundreds); we work in a reed that not changed in the last twelve years.
What is the situation in Great Britain?
Thanks and congratulations for your work.