Himalayan Monal Adapts Call Frequencies to Combat Human-Generated Noise

The Himalayan monal, Uttarakhand's state bird, is demonstrating a remarkable adaptation to increasing human activity in its habitat by altering its vocalizations. Researchers at Hemvati Nandan Bahuguna Garhwal University have found that monals in noisier parts of the Himalayas, affected by traffic, tourists, and pilgrims, are calling at higher peak frequencies and for slightly longer durations. This finding, published in Behavioural Processes in August 2025 by Rajeev Lochan, Dinesh Kumar Sharma, and Anand Kumar, suggests the birds are actively trying to be heard above the amplified soundscape.

The study involved recording 719 monal calls between April 2023 and June 2024 across two distinct valleys within the Kedarnath Musk Deer Sanctuary: the relatively quiet Madmaheshwar Valley, which lacks roads and experiences minimal human presence, and the busier Chopta Valley, frequented by vehicles, trekkers, and birdwatchers. Researchers utilized directional microphones and AudioMoth recorders, focusing on morning and evening periods when monals are most vocal. The data revealed that monals in the noisier Chopta Valley consistently produced calls with higher peak frequencies, particularly at the upper end of their vocal range, with a median difference of approximately 171 Hz compared to the quieter habitat. A slight increase in call duration was also observed under noisier conditions.

This vocal shift is interpreted as a response to acoustic masking, a phenomenon where background noise overlaps with an animal's communication signal, making it difficult to detect. Human-generated noise, often occupying frequencies essential for wildlife communication, compels the monal to adjust its calls to higher frequencies, potentially as a mechanism to reduce this masking effect and maintain effective communication for mating and territorial defense. While the monal, which ranges from Afghanistan to Bhutan across high-altitude forests and alpine landscapes (2,400 to 4,500 metres), has not relocated, its vocal adaptation highlights the pervasive impact of human activity on wildlife.

However, the long-term costs of this adaptation remain unknown. The study does not establish whether these altered calls impact mating success or population dynamics, nor does it confirm the birds' indefinite capacity to compensate for escalating noise levels. Furthermore, a separate 2025 study by the same researchers in Scientific Reports projected potential habitat losses for the monal under various climate scenarios, with over 14% of suitable habitat becoming unsuitable by 2041–2070 under one scenario. Despite being classified as Least Concern on the IUCN Red List globally, local habitat changes due to climate change, land-use shifts, infrastructure, and tourism pose ongoing challenges, emphasizing the need for further research into the broader implications for the monal and other Himalayan bird species.

Why it matters: It shows how wildlife creatively adapts to human impact, but also highlights the need to understand the limits of such resilience.

Editor's note: Detailed, faithful adaptation of the wildlife study on Himalayan monals, covering methodology, results, and context.