Beastly accurate
Spring time, bird song time: Gradually, the migratory birds are returning from their sunny winter quarters to their breeding grounds and join in the chorus of their singing brothers who spend the winter in this country. But if you pay close attention, you can almost set your watch by the beetle.
For passionate bird lovers - as the author of this article can claim - there is hardly anything nicer than being woken up by the morning chirping, whistling and trilling of blackbirds, thrushes, finches and starlings. Die-hard ornithologists even get up at night to be in the surrounding woods and meadows before the morning concert begins, so as not to miss any of the organists, trumpeters or flutists.
On the other hand, one must also admit that there are also human owls who would prefer to ban blackbirds from appearing in the early hours and would like to oblige the birds to comply with the statutory noise immission values. But seemingly punctually to the minute, more and more new singers start with their musical contribution, until finally it sounds euphonious and full-bodied from every corner and end - a phenomenon that is called the bird clock.
But what exactly is this bird clock? And how does it work? In principle, it indicates the chronological sequence in which various bird species native to Germany begin their morning song. This is controlled by the time of sunrise, which of course moves forward in the course of spring, and thus by the development of daylight. This is why the birds also increasingly start their day earlier in the course of the quarter. However, the time between the first whistle and the actual appearance of the sun remains largely the same.
The redstart, the first indicator of the bird clock, always greets the day ninety minutes before our stellar ball of embers appears on the horizon - if mid-May is the relevant period, this increasingly rare migratory bird would be heard at four in the morning. It is followed ten minutes later by the robin with its babbling warble and after another five minutes by the blackbird, whose powerfully sounding and melodic singing has probably driven some out of bed earlier than planned.
At 4:20 am they are joined by the wren, whose incredibly loud organ is inversely proportional to his small body. It is followed by a ten-minute break before the cuckoo, whose name reflects the sound it makes, comes on at half past four. Next, at 4.40 a.m., the great tit starts the day with its chatter and at 4.50 a.m. the chiffchaff, which is also named after its reputation as "zipzipzip-do-you-want-to-go-with-me?" – on the vocalizations. Finally, at around 5.20 a.m., the well-known and popular house sparrow wakes up, before the sun rises at half past five. Only ten minutes after this drastic event does the starling finally call out from the cherry tree or from the wire and thus participate in the sanchronometric alarm clock.
Of course, the timing does not serve to annoy or make people happy, but of course has biological reasons: by singing one after the other, the birds avoid polyphonic overlays, and so the individual sings not immediately drowned out. This makes it easier for the species to define their territory and courtship, as it makes it easier to locate the males. The acoustics are also best in the morning, since atmospheric disturbances such as winds are weak at best. As they heat up, they intensify over the course of the day and can thus significantly influence the transmission of bird calls - one of the reasons for the decrease in song activity during the day, which only picks up again towards the evening. It is also important to recognize predators, which are based on vocalizations: Consequently, birds start singing when the light intensity is sufficient for them to spot predators in good time, but this is not yet intense enough to pursue the urge to eat themselves.
Because the time of sunrise differs from south to north, birds begin singing at different times from region to region. Even in the tropical rain forests, the morning light directs the concerts - so even there, those who don't wake up in the morning can't escape the lively fowl.
