Birdsong at first light has long enchanted both birdwatchers and scientists, but the reasons behind that dawn chorus have remained elusive. A new study finds that it isn’t the cool, still air that drives early‑morning singing so much as social stakes and dinner plans.
Researchers from the Cornell Lab of Ornithology’s K. Lisa Yang Center for Conservation Bioacoustics and Project Dhvani in India deployed passive acoustic monitoring across 43 sites in India’s Western Ghats, a global biodiversity hotspot.
“Passive acoustic monitoring allowed us to collect simultaneous acoustic data for 43 locations, over several months,” says lead author Vijay Ramesh. “We could not have done this study without it because we needed a lot of data to answer our questions.”
By cataloguing vocalizations of 69 species throughout the day, the team discovered that 20 species, among them the Gray‑headed Canary‑Flycatcher and the Greater Racket‑tailed Drongo, sang substantially more at dawn than at dusk. Only the Dark‑fronted Babbler bucked the trend, calling more often in the evening.
To untangle why some birds favor first light, Ramesh and colleagues considered four prevailing theories: whether cooler morning air improves sound transmission, whether dawn singing wards off rivals, and whether early calls set the stage for foraging flocks. They then incorporated existing data on each species’ territoriality and diet to test which factors mattered most.
“We found that highly territorial birds and omnivorous species were much more likely to be active singers during dawn hours,” Ramesh explains.
Territorial calls may serve as a clear “do not trespass” signal when sunlight is still low, while omnivores, often members of mixed‑species foraging flocks, might need to coordinate with flock mates before insects and fruit become plentiful.
Surprisingly, environmental factors such as light levels and sound‑transmission conditions had little effect on dawn singing, challenging long‑standing assumptions.
“Our findings demonstrate that social factors, particularly territoriality and feeding habits, are more important in driving dawn singing behavior than environmental conditions,” Ramesh says.
Understanding these behavioral drivers could improve our ability to monitor ecosystem health via acoustic surveys and may even inform conservation strategies for species whose dawn songs mark critical breeding or foraging behaviors.
The study has been published in Philosophical Transactions of the Royal Society B.
