© Marcel Burkhardt
The return of migratory birds
Migratory birds are the heralds of spring. Each species follows a clear schedule when returning from its winter quarters. Common Starling and White Wagtail announce the early days of spring, while Common Swift and Common Nightingale return in late April.
In general, birds that winter in the Mediterranean and therefore have a shorter distance to cover arrive earlier than those returning from far-away tropical Africa.
The weather can delay the migrants’ schedule by a few days, but it will not significantly alter it. Climate change, however, has resulted in certain species arriving several days earlier than they did thirty years ago.
“One swallow does not make a summer.” As the saying implies, not all individuals of a particular species return at once. The first Barn Swallows are usually sighted around 20 March, the main group in the first half of April, and the last individuals not until the end of May. In many species, the males arrive several days before the females in order to secure a good nesting site.
Schedule of return migration
The schedule applies to the Swiss Central Plateau. The migrants arrive slightly earlier in Ticino and the milder areas around Lake Geneva and Basel, and somewhat later in the pre-alpine zone.