Sri Lankan bird waves
Posted by BESG on 3 January 08, Thursday
Contributed by - see article -
On 14th December 2007, Eben and Uromi Goodale (left) were at the Department of Biological Sciences, National University of Singapore to deliver a seminar on “Mixed-species bird flocks: Linking communication, community ecology and conservation.”
Eben is an ornithologist working on behaviour and community ecology, currently a postdoctoral fellow attached to the University of Colombo and the University of Papua New Guinea. Uromi, a plant ecophysiologist working on reforestation, is currently working on her PhD.
Eben has been chasing birds in Sri Lanka’s Sinharaja rainforest for years, studying flocking. In what we call bird waves, two or more species move in the same direction in search of food.
Birds generally gather in flocks during resting, feeding, roosting and moving during migration… and in bird waves. In the lowland forests of Sinharaja, mixed flocks of large bird waves are made up of an average of 12 species and up to 40 individuals or more. These are mainly babblers, a few drongos and maybe also, monarch and bulbul.
The babblers make up the nucleus of the waves. These are gregarious forest birds, and in the process of gleaning for insects, force other insects into the open. This in turn provides foraging advantages to the few drongos that are present. The drongos provide an anti-predation role in their alarm calls when threats appear, usually alarm calls of other species, especially raptors.
According to Sri Lankan birder and nature guide Amila Salgado, during October to April, migrants such as Asian Paradise-flycatcher (Terpsiphone paradisi) and Chestnut-winged Cuckoo (Clamator coromandus) also join in, increasing the species composition of the flock. Orange-billed Babbler (Turdoides rufescens) and Sri Lanka Crested Drongo (aka. Greater Racket-tailed Drongo Dicrurus paradisus), are jointly regarded as ‘nuclear species’. The former, highly gregarious and almost constantly babbling, help birds and birders to locate the flock.
Input by Eben and Uromi Goodale and Amila Salgado; image of the Goodales by YC.
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Categories: Feeding strategy, Travel, Personality
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