MJB
Well-known member
This is indeed the oldest and most common conception of 'reverse migration' but I have always doubted the wisdom of the term 'genetic abnormality'. Far from being abnormal is it not essentially normal for a small percentage of a breeding bird population to behave in a different manner to the masses, thus exploring new (potential wintering/breeding) territory? Is this not what the dynamics of bird populations are all about? Genetically different perhaps, but not abnormal.
I think your succinct assessment is a basis for Ian Newton's scepticism about genetic abnormalities being a significant cause of misorientation. I'm grateful to Tideliner for taking the time to demonstrate that there isn't a reasoned consensus on the use of the term 'reverse migration'; it's just that Peter Berthold describes many variations of migration strategy and how each varies, but he does so with careful thought as to 'definitions of terms'. In general, I'm more convinced by meticulous coverage across a broad canvas than by individual studies. However, there are always exceptions!
MJB