Snow in the Mountains

I had no sooner posted last week’s piece about David and Elizabeth Lack in the Pyrenees when there were barn swallows everywhere in the Biros Valley. Until then I had seen no sign of the sort of visible migrations described by the Lacks, possibly because mid-September is a bit too early for that. For the …

Grandeur and Novelty

How do small land birds migrate past high mountain ranges? This is not a question that has often been asked in the Americas because most of the big mountain ranges run north-south. But in Europe, where the Alps and the Pyrenees would seem to be a formidable barrier to migration (see map below), this issue …