Ithaca, NY— A new study published in Philosophical Transactions of the Royal Society B reveals that both territorial behavior and diet play key roles in determining why certain bird species sing more frequently at dawn.
Tracking Bird Songs in India’s Biodiversity Hotspot
Researchers from the Cornell Lab of Ornithology’s K. Lisa Yang Center for Conservation Bioacoustics, in collaboration with Project Dhvani in India, examined 69 bird species from the Western Ghats—one of the planet’s major biodiversity hotspots—to explore the factors influencing how often birds sing throughout the day.
The researchers used microphones across the forest for passive acoustic monitoring to automatically capture bird sounds. This approach records continuous audio that scientists later analyze to identify which bird species were vocalizing. Passive acoustic monitoring enabled us to simultaneously collect acoustic data from 43 different sites over several months. Lead author Vijay Ramesh of K. said the data volume needed would have been impossible to obtain otherwise. Lisa Yang Center for Conservation Bioacoustics.
Why Birds Sing More in the Early Morning
Their analysis revealed that 20 bird species were significantly more vocal at dawn than at dusk. These early-morning singers included the Gray-headed Canary-Flycatcher, Greater Racket-tailed Drongo, and Large-billed Leaf Warbler. In contrast, only one species—the Dark-fronted Babbler—was found to vocalize more frequently in the evening.
Ramesh and his team explored four potential explanations for why many of the bird species they studied sang more frequently at dawn than at dusk. Existing hypotheses suggest dawn choruses are shaped by microclimatic factors like low wind and cooler temperatures, which help high-pitched songs carry farther and clearer. Other explanations propose birds sing at dawn to defend territory or prepare for feeding as light and insect activity rise. The researchers tested these ideas by combining their recordings with previous data on species’ territorial behavior and diet.
“We discovered that birds with strong territorial behavior and those with omnivorous diets were significantly more likely to sing during dawn hours,” Ramesh explained. The authors propose that early-morning singing helps territorial species assert and defend their space. Omnivorous species—those that consume both fruit and insects—also tended to sing more at dawn. Ramesh suggests this might be because omnivores often join mixed-species foraging groups, where vocal signals are key for coordinating feeding and alerting others to predators. However, he noted that further research involving direct visual observations is needed to verify this hypothesis.
Social Factors, Not Environment, Drive Dawn Singing
The researchers found that other environmental variables they analyzed—such as light intensity and how well sound travels—had little effect on the timing of bird songs, calling into question earlier hypotheses about why birds are more vocal at dawn.
“Our results show that social factors, especially territorial behavior and feeding strategies, play a greater role in shaping dawn singing patterns than environmental conditions,” Ramesh explained.
Read the original article on: The Cornell Lab
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