Whether you’re an ‘early bird’ or a ‘night owl’, you’re probably familiar with a certain melody heard around the world: the chorus of birdsong at dawn and dusk. Most noticeable in the springtime, males of many songbird species participate in a twice-daily round of singing synchronized to start before the sun rises and again before it sets. Despite being such an easily recognizable natural occurrence and classic signifier of the new day, the question persists: why does this chorus happen? Many hypotheses have been put forth over the years, but a definitive answer has proved elusive due in part to the utter variety of birds’ daily patterns and vocalizations. 

Now, researchers at the Max Planck Institute for Biological Intelligence have come up with a simple, universal explanation for why male birds chorus at dawn and dusk. They propose that a chorus is inevitable if most males leave the roost earlier in the morning and return later in the evening than their female counterparts, and provided that separation from their mate prompts males to sing. To test this, the researchers studied mated pairs of blue tits, a common species of bird that has been previously shown to meet both conditions. They recorded the vocalizations of males during the dawn, day, and dusk, while simultaneously monitoring when their female mates were absent using RFID technology, which relies on small radio-frequency enabled tags to track individual animals. They found that across all times of the day, males sang more when females were absent. They also found a wealth of anecdotal data suggesting their hypothesis holds true in other bird species, and could even explain variation in birdsong intensity, presence, and absence across different seasons, warranting further experimental studies in the future.

One of the cardinal (pun intended) motivations of scientific research is to understand why the beautiful things we observe in the natural world around us happen. Thanks to this useful general explanation for birdsong, we’ve come closer to doing just that, making this a scientific result that’s nice to hear in more ways than one. 

This study was led by Lotte Schlicht, a postdoctoral researcher at the Max Planck Institute for Biological Intelligence. 

Managing Correspondent: Maati McKinney

Press Article: Absence of female partners can explain the dawn chorus of birds (Nature News & Views)

Original Journal Article: A dawn and dusk chorus will emerge if males sing in the absence of their mate (Proceedings of the Royal Society B)

Image Credit: Pixabay/neelam279

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