Although it is still winter according to the calendar, birds can already sense the arrival of spring. While the first species are making their way back from their southern wintering grounds, others are already singing to claim their territories or have even begun to breed.
At dusk, a familiar sound we associate with spring and summer has been audible these past few days: blackbirds are singing! This is a delight, though it may also raise some questions. To address these straight away: blackbirds are among the first heralds of spring. It is perfectly normal for them to be singing as early as February.
But the blackbird is not the only bird sensing the change of season: owls such as the eagle owl and the Tengmalm’s owl are calling to mark their territories, peregrine falcons are performing courtship flights, and rooks are busily gathering twigs for their nests. Even earlier is the bearded vulture: it has been sitting on its nest and incubating since January, or even December!
Spring does not always announce itself so conspicuously. The return of migratory birds is barely visible at the moment, because it takes place at night. Thanks to a radar installed on the visitor centre of the Vogelwarte, all movements of migrating birds over the station are recorded. The number of birds passing through has increased sharply over the past week or so. The radar also provides information about the direction of flight — pointing north-east, which is a clear sign that the bird migration has begun. This early in the year, it is primarily birds returning from their wintering grounds in the Mediterranean region that are on their way back.
Schedule for the return of migratory birds
Migratory birds are harbingers of spring, and the various species follow a clear schedule. Common starling and white wagtail herald the early spring, common swift and nightingale return in the final days of April.
In general, species that wintered in the Mediterranean region and therefore have a shorter route to cover arrive earlier than those returning from the distant tropical regions of Africa.
The weather can shift the schedule of migratory birds by a few days, but cannot fundamentally change it. However, climate change means that various species now arrive a few days earlier than they did thirty years ago.
«One swallow does not make a summer«. The proverb suggests that even within a species, not all individuals return home at the same time. The first barn swallows are usually spotted around 20 March, the main wave in the first half of April, and the last ones 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.
