In my neck of the woods redwings and fieldfares have been much less common over the last couple of years, which I put down to mild winters, hence less need for them to travel south and west.
Somewhere else on the forums, though, I read that many are now wintering in Scandinavia, again, seemingly, because life is less hard for them there.
Which started me wondering.
If there were a succession of years in which migration across the North Sea became rarer, would the remaining birds lose the tradition of heading across the sea?
To put it another way, I'm wondering whether, or perhaps to what extent, these migrations are instinctive or learned.
I wonder if anyone knows whether the migrations occur in family groups.
If the chicks of a particular season migrate with their parents, it would seem to me quite plausible that the migration pattern could just be lost, in a succession of years in which little or no migration occured.
OTOH, if the seasons chicks travel independently of their parents, I'd guess that the migration is much more instinctive than learned.
Then again, perhaps these aren't even sensible questions. Though I do gather tha at least some migration behaviour is learned. No?
David