Western Ghati are an Indian mountain range that is considered a “hot point” For world biodiversity: in addition to hosting 30% of all animal and vegetable species of the continent, it acts as a refuge for at least 325 species in the process of extinction.
Precisely because of his biological wealth a team from the Cornell Lab of Ornithology has chosen the Ghati to study in depth a fascinating and still unexplained phenomenon: why do some birds sing more often at dawn than in the rest of the day? The study was published on Philosophical Transactions of the Royal Society B.
At dawn I will sing. To find out why the Ghati birds behave as in the well -known English saying “The Early Bird Gets the Worm” (the bird that wakes up before eats the worm), the team has placed a series of microphones in 43 different locations in the tropical forest which stands in the Indian mountains. During a study lasting months, the team collected the vocalizations of 69 different species of birdsdiscovering that most prefer the dawn to sing.
Not everyone must be said: there are 20 species in particular that sing almost exclusively at the first light of the dayothers that distribute the songs more uniformly throughout the day (but always preferring the dawn), and a single species, Dumetia Atricepswhich instead prefers sunset. In general, however, the study of the data collected confirms that the dawn is the “hottest” period for singing birds.
Why is dawn better? Why do many birds, at least on the Ghati, prefer dawn? There are at least four different theories that could explain it. The first suggests that it is a matter of microclimate: In the morning, the presence of wind and the air temperature allow the songs to spread better. Another possibility is that singing at dawn help a defend their territory from the early hours of the day and report their presence. There are those who claim that birds cantine so much in the morning to then be able to spend the rest of the day looking for foodand finally there is the idea that birds do it because too insectsthat is, their prey, are more active at dawn.
A mix of factors. According to the authors of the study, the answer is a combination of these theories. The most territorial birds, for example, almost always sing at dawn, to report their presence from early morning and keep the invaders from the territory away.
Omesome birds also prefer dawn: according to the authors this happens because theirs communications are essential to report the presence of food to each otherand in the morning the forest is relatively quieter. To find out more, a series of active observations must be started, to be combined with the acoustic data recorded by the microphones; For now, however, it seems clear that the preference for dawn is dictated first of all by “social” reasons.
