Himalayan Monal Adapts Its Calls to Noisier Environments

The Himalayan monal, the state bird of Uttarakhand, is demonstrating a remarkable adaptation to the increasing human-generated noise in parts of the Himalayas. Researchers at Hemvati Nandan Bahuguna Garhwal University have discovered that these birds are adjusting their vocalizations, calling at higher frequencies and with slightly longer durations in areas impacted by traffic, tourists, and pilgrims. This behavioral shift allows the monal to remain in its habitat and cope with a louder soundscape, rather than being displaced.

A study by Rajeev Lochan, Dinesh Kumar Sharma, and Anand Kumar, published in Behavioural Processes in August 2025, meticulously compared monal calls from two distinct settings: the relatively quiet Madmaheshwar Valley and the busier Chopta Valley within the Kedarnath Musk Deer Sanctuary. Between April 2023 and June 2024, researchers utilized directional microphones and passive acoustic monitoring devices, including AudioMoth recorders, to capture 719 monal calls. Their analysis revealed that monals in the noisier Chopta Valley produced calls with higher peak frequencies and slightly longer durations. Specifically, the median peak frequency in the quieter habitat was around 171 Hz lower than in the noisier one, with the pattern being strongest at the upper end of the birds' vocal range.

This adaptation is understood through the ecological concept of acoustic masking, where background noise overlaps with an animal's communication signal, making it harder to detect. Human-generated noise from roads, vehicles, and machinery often occupies frequencies vital for wildlife communication. The monal appears to be shifting its calls towards higher frequencies to mitigate this masking effect and ensure its calls travel more effectively through its habitat. A slightly longer call duration could also serve to maintain communication when background noise interferes with the signal, enabling the bird to communicate, find mates, and defend its territory despite the altered soundscape.

While the study highlights the monal's capacity for behavioral flexibility, scientists note that the long-term costs of this adjustment are not yet known, nor does it establish that these changes reduce mating success or guarantee indefinite compensation for increasing noise. However, this immediate response demonstrates the species' ingenuity in adapting its voice to persistent environmental changes. The monal's native range extends from Afghanistan and Pakistan through the Himalayas in Nepal, India, southern Tibet, and Bhutan, thriving in alpine and subalpine areas between 2,400 and 4,500 meters. This ongoing research by Lochan, Sharma, and Kumar also explores the species' future habitat suitability under climate scenarios, indicating potential habitat losses towards the end of the century, emphasizing the broader environmental pressures.

Why it matters: This adaptation demonstrates the resilience of wildlife in responding to human-induced noise pollution.

Editor's note: The draft provides a comprehensive and accurate summary of the research study, its methodology, and the implications for the species.