Increased human activity is affecting the Himalayan monal, a pheasant native to Himalayan mountain forests, according to two studies by Indian researchers. The studies found that infrastructure development and tourism are reducing the bird's habitat and increasing noise, which is altering its communication.
One study found that monals are being forced to move higher into the mountains as their natural alpine meadow habitats above the tree line become crowded. The other study indicates that the monal is changing its vocal pitch to be heard over human noise in busy valleys.
Researchers recorded over 700 monal calls and found that birds in noisy environments consistently produced calls with significantly higher peak frequencies compared to those in quieter habitats. The study also noted that monals in noisy areas produced shorter call durations, possibly to cut through low-frequency human noise from traffic and tourists. These changes are considered behavioural flexibility rather than permanent evolutionary shifts.
Dr. Rajeev Lochan, lead researcher for both studies, stated that the monal's narrow habitat range makes it a key indicator of ecosystem health in the north-western Himalayas. The research suggests that if the monal is facing issues, other species might also be affected by ecological disturbances.