Do you feel like you’re waking up like in a fairy tale, by birds singing longer and louder than before? You are not dreaming (or at least not completely). If their trills seem longer and more present than before, it is because our winged companions really prolong their concerts. But behind this Snow White atmosphere lies a much less magical reality: the light pollution that humans generate has completely modified their natural cycles.
According to an article in the online media New Atlas, a team of university researchers from Southern Illinois University and Oklahoma State University (United States) studied 2.6 million beginnings and endings of bird songs as part of a participatory project BirdWeather. This program is based on the installation of bioacoustic recorders set up in the gardens of volunteer citizens. Analysis of these results reveals a striking observation: species located in areas most polluted by artificial light sing on average 50 minutes more per day than those living in natural darkness.
Specifically, birds in these lit landscapes begin singing 18 minutes earlier at dawn and 32 minutes later after dark. In the magazine Sciencethe study authors state: “This prolonged activity can represent a substantial loss of rest, particularly during the breeding season.”
Unknown consequences
However, they qualify their remarks by adding that it is possible that the birds compensate for this apparent lack of sleep by resting more during the day, or by sleeping only half of the brain. They add that conversely, this new distribution of waking time could even favor the search for food and reproduction.
The bird species that are most sensitive to this phenomenon are those that have large eyes, that nest in the open and that occupy large territories. As far as they are concerned, the impact of light is especially evident during the mating season. Michael Franco, science journalist for New Atlasadds that researchers, however, remain cautious. At this time, it is impossible to determine whether altering song cycles is beneficial, harmful, or neutral for overall bird health.
It is estimated that 80% of terrestrial life forms today evolve under artificially lit skies. This global light halo causes the death of insects attracted to the lamps, disorients migratory birds and even diverts young sea turtles from their path to the ocean.
Researchers call for global awareness and the implementation of strict political measures comparable to those taken against climate change. “Restoring the darkness of our nights is a major conservation challenge in the 21st century and requires global cooperation”concludes the team.
