Wild Asia - Endemic Enigma: Searching Out Peninsular Malaysia's Whistling Thrushes

Follow DAVE BAKEWELL and his team on a conservation effort to uncover the truth and dispel the myths surrounding our whistling thrushes.

The hauntingly beautiful notes of a flute rise and lilt through the chambers of a large cave in the soft pre-dawn light, to be answered, magically, by an equally beautiful cadence from an unseen bird somewhere deep in the recesses of the cave.

The flute player comes often to offer his gift of music in the caves of the Kek Look Tong temple in Ipoh, Perak, and his accompanist is a Blue Whistling-Thrush. The thrush flies down from its favourite perch high among the stalactites to the cave floor to look for crumbs left out for it by the temple workers. It is large for a thrush--almost pigeon-sized--with deep violet-blue plumage and a powerful hooked yellow and black beak. The tail spreads and snaps shut in a constant rhythmic motion reminiscent of a lady opening and closing a Chinese fan.

The thrush takes off to fly up to the cave roof once more, but suddenly it's caught in mid-flight, entangled in an unseen net. Gentle and skilled hands endure the powerful blows of that fearsome bill as the bird is quickly removed from the net and meticulously weighed and measured, before being fitted with two coloured plastic bands, one on each leg, and released.

The hands that extracted, measured and released the thrush now bear fresh and bloody wounds as a result of the bird's indignation at being subjected to such humiliation. They belong to Lim Kim Chye , Taiping based bird-ringer and Wild Asia Associate, who seems surprisingly cheerful despite the pain!

Kim Chye is part of a specialist team researching Peninsular Malaysia's whistling thrushes. The project focuses on two species of whistling thrushes which are resident in Peninsular Malaysia; the Blue Whistling-Thrush and the endemic Malaysian Whistling-Thrush.

Until recently, it was thought that the two species had an allopatric distribution--that is, they never occur alongside each other--being separated by altitude above sea level. The Malaysian Whistling-Thrush is known to be a bird of montane forests from around 750 to 1,750 metres above sea level, while the Blue Whistling-Thrush was thought to occur only in the lowlands. On the basis that a healthy montane population of whistling thrushes at Cameron Highlands was assumed to be Malaysian, the conservation status of the species is currently listed as "of least concern".

However, a number of factors make whistling thrushes difficult to identify to species level. They prefer habitats such as caves and dark forested ravines where light conditions are poor, and they are most active at dawn and dusk, further diminishing the chances of seeing them well. Malaysian and Blue Whistling-Thrushes have extremely similar plumage and are mainly differentiated by the former being about 15% smaller than the latter. Estimating the size of a bird in the field, unless both species are seen side by side, is extremely challenging, and it is difficult to establish certain identity of a whistling thrush observed in the field, even with good photographic evidence.

These factors, and concerns that perhaps our endemic Malaysian Whistling-Thrush was scarcer than reports suggested, led to the initiation of this project. The team have been studying whistling thrushes at four targeted study sites; two in the lowlands (Ipoh and Perlis State Park) and two in the mountains of the main Titiwangsa range (Cameron Highlands and Fraser's Hill).

During each site visit, which normally lasts four days, the team, assisted by willing volunteer helpers, sets up mist nets to attempt to catch the birds. In addition, birds are observed, photographed in the field, and their calls and songs are recorded. Trapped birds are each fitted with a unique combination of coloured leg bands, which enables them to be identified easily in the field. It is hoped that tagging of individual birds will enable the team to learn more about the territory size, movements and social interactions of the thrushes.

Results to date have confirmed the team's suspicions that the Malaysian Whistling-Thrush is far scarcer than was previously assumed. All the birds observed and caught in the Cameron Highlands have proved to be Blue Whistling-Thrushes, thus exploding the myth that the two species are separated by elevation. A Blue Whistling-thrush has also been observed at Jeriau Waterfall, Fraser's Hill, which is internationally known as one of the best places to see Malaysian. To date, the team has not recorded or caught a single Malaysian Whistling-Thrush. The clear implication of these findings is that an upgrading of the conservation status of the species is needed.

Historical records suggest that the Malaysian Whistling-Thrush was formerly more widespread than it appears to be currently, begging the question of what has triggered the decline, if indeed one has occurred. Possible culprits include rising temperatures at hill stations, resulting in an increased competition from 'lowland' species which are now moving in; and continuing development of hill stations, which has included the opening up of forested ravines, canalizing of streams and an increase in water pollution. While the Blue Whistling-Thrush seems to be fairly resistant to these changes, the Malaysian may be less so.

What is certain is that the ecological requirements of one of our most elusive endemic birds remain unclear, and need to be further investigated as a matter of urgency. Understanding of the precise needs of the Malaysian Whistling-Thrush is a necessary prerequisite for effective conservation measures which will hopefully ensure that this rare thrush remains part of Malaysia's unique natural heritage.

Kim Chye is part of a team conducting a project entitled A Preliminary Assessment of the Field Identification, Status and Population of Regionally Endemic Whistling Thrush Taxa in Peninsular Malaysia, funded by the Tan Kean Cheong Bird Conservation Memorial Fund, which is administered by the Malaysian Nature Society, Perak Branch. The other core members of the team are Dr Shahrul Anuar bin Mohd Sah of the School of Biological Sciences at Universiti Sains Malaysia, and Dave Bakewell, environmental consultant and WA Associate. The project began in April 2009 and will run into 2010.