The Malabar Whistling-thrush has high-pitched human-like whistles that carry over the low-frequency ...

The Malabar Whistling-thrush has high-pitched human-like whistles that carry over the low-frequency noise of streams and waterfalls in India’s forests. UV-reflecting feathers may also be used as signaling devices. 

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The Malabar Whistling-thrush likes to nest in dense stands of teak, jamun, cashew and other trees on rocky ledges along India’s protected pristine streams. This habitat in places like the Pachmarhi Biosphere Reserve is also favored by the Honey Buzzard, Black Eagle, Malabar Pied Hornbill, Paradise Flycatcher and many other stunning bird species.

The evolution of some birds’ songs appears to be heavily influenced by ambient acoustics. For example, the Screaming Piha has compensated to life in dense, noisy forests by increasing the volume of its songs into the deafening range. Urban populations of some birds produce higher pitched songs, possibly to carry over low-pitched traffic noise.

The role of ambient acoustics makes the Malabar Whistling-thrush one of several important species in the study of evolution of bird song. Another species, the Rufous-faced Warbler, produces even higher pitched songs in the ultrasonic range beyond the audible range of humans. This Warbler also nests along noisy streams farther east in Asia. 

The Malabar Whistling-thrush may have other communication tricks up its feathers. It is a beautiful black-colored bird with a band of royal-blue feathers on its forehead, back and belly that flash brilliant violet (to humans) in sunlight. 

Whistling-thrushes and some parrots have UV-reflective microstructures in their feathers that may be involved in signals that are invisible to humans. Might the Malabar Whistling-thrush use UV signaling in courtship or in routine communications to circumvent ambient noise?

The male Budgerigar is one of many parrot species that has fluorescent plumage adjacent to UV-reflective plumage. This pattern leads to a high color contrast in the eye of beholding females. Some evolutionary biologists theorize that courtship signals based on UV contrast and signaling are important to at least some birds. 

Peter Mullen, a biologist at the Alexander Koenig Zoological Research Museum in Bonn, Germany, discovered that dark-blue feathers of Whistling-thrushes (and other birds) also reflect UV light.

“Bird of many more groups may see UV light than have been studied to date,” Koenig wrote in a 2008 paper in Ibis. “Although we do not know if UV phenomena play a role in visual signaling, they might be more suggestive of a signaling role than the UV reflections which only add to the overall brightness of a bird’s plumage.”

(Photo: Adam Riley)

I believe that the more that people know about the Malabar Whistling-thrush, and the more time they spend watching, enjoying and photographing it the better for the species, all birds, all wildlife and the human race.