As the first light spills over the emerald canopy of India’s Western Ghats, the forest erupts in song. Birds trill, warble, and whistle in a delightful chorus that has fascinated biologists and birders alike for generations.
This daily ritual — the dawn chorus — is one of nature’s most familiar yet least understood performances.
Why do so many birds sing so vigorously at dawn, only to quiet down as the sun rises?
A new study offers a compelling explanation that shifts the focus from the atmosphere to the animals themselves. Researchers found that birds sing more in the early morning not just because the air is still and sound travels farther, as long assumed — but because they’re defending territory or coordinating food hunts.
“Our findings demonstrate that social factors, particularly territoriality and feeding habits, are more important in driving dawn singing behavior than environmental conditions,” said lead author Vijay Ramesh, a postdoctoral researcher at the Cornell Lab of Ornithology’s K. Lisa Yang Center for Conservation Bioacoustics.
Listening to the Forest
The study centered on the Western Ghats, a rugged mountain range stretching along India’s western coast. A UNESCO World Heritage Site, it’s one of the most biodiverse places on Earth — and a birdwatcher’s paradise.
Over several months, Ramesh and his colleagues from Project Dhvani deployed microphones across 43 forest locations to record the songs of 69 bird species. The method — known as passive acoustic monitoring — captures sounds across the day, allowing researchers to analyze when and how birds vocalize.
“Passive acoustic monitoring allowed us to collect simultaneous acoustic data for 43 locations, over several months,” said Ramesh. “We could not have done this study without it because we needed a lot of data to answer our questions.”
The result was an immense audio archive of the forest’s daily rhythms. Out of the 69 species studied, 20 sang significantly more at dawn. These included the large-billed leaf warbler and the greater racket-tailed drongo, both known for their striking calls. Only one species — the dark-fronted babbler — preferred dusk to dawn.
So, why do birds sing more at dawn? One idea is that early morning air carries sound better, particularly high-pitched songs. Another is that light levels are too low to forage, so singing fills the idle time. A third holds that dawn singing helps birds secure mates or assert territory.
The researchers tested all these ideas.
They combined the acoustic recordings with information from existing literature — looking at each bird species’ diet, territoriality, and other ecological traits. They expected to see some influence from the environment. But what stood out instead were social behaviors.
“We found that highly territorial birds and omnivorous species were much more likely to be active singers during dawn hours,” Ramesh said.
In other words, birds that stake out and defend turf sing more in the morning — presumably to announce themselves to rivals. And species with diverse diets, including fruit and insects, also sing more. These birds often join mixed-species flocks, where early morning communication may help coordinate foraging or alert others to danger.
Environmental factors like temperature, light, and sound transmission turned out to be surprisingly minor.
A New Framework for Understanding Birdsong
This doesn’t mean that physics plays no role in bird behavior. After all, a quiet morning may still help a bird’s song carry farther. But the new findings suggest these effects are not the main drivers of dawn choruses.
The study’s conclusion is clear: birds sing early because they have something to say at that time, not just because it’s easier to be heard.
Still, many mysteries remain. The team notes that more research — particularly direct visual observations — will be needed to fully understand the social interactions that drive dawn vocalizations. Ramesh suspects, for instance, that omnivores may rely more on group behavior, which demands more communication.
That idea could reshape how scientists view birdsong itself. Understanding how and why birds sing can help conservationists monitor fragile ecosystems. Passive acoustic monitoring, the technology used in this study, is becoming a powerful tool for detecting species presence, especially in remote areas.
It’s also timely. The Western Ghats face increasing pressure from deforestation and climate change. Knowing when and why birds sing could offer new ways to track their behavior, detect stress, and identify changes in population dynamics.
In a world where many birds are going silent, listening to their songs more carefully could help us save them.
The findings were reported in the journal Philosophical Transactions of the Royal Society B.
