Friday, 23 August 2013

Passerines 6: Sumatran Laughingthrush

Sumatran Laughingthrush
Widespread throughout Asia are a group of medium sized to large passerines, the laughingthrushes, Garrulax spp., with at least 50 species. Despite their name, they are not considered especially close to the true thrushes, Turdus spp., instead being placed currently in a separate family Leiothricidae, generally considered close to the various species of babblers in the Timaliidae.

However they are classified, laughingthrushes are noisy, active and sociable birds with a loud song. They tend to move around in small flocks outside the breeding season, separating into pairs to nest. As one might expect from their large size (25cm beak to tail length) they can tackle large food items, feeding on fruit, insects, and in the wild probably small lizards or even hatchling snakes, as well as raiding other birds nests for eggs and nestlings. Consequently, in captivity if they are in a mixed exhibit they do best with birds at least their own size such as pigeons or starlings, as smaller finch-sized birds may become a meal.

The natural habitat for most species is fairly dense undergrowth, where they spend a lot of time foraging on the ground. They are not especially good flyers, and do not seem to migrate long distances, although montane species make vertical movements down into the valleys during the winter. The various species range from montane forest, through sub tropical scrub, down into true rainforest, and several species will happily live and nest near villages.

Laughingthrushes build a fairly typical cup-shaped nest of plant material, lined with feathers. The clutch is usually 4 or 5 eggs, and the young take around 21 days to fledge, although this varies between species.
White-Crested Laughingthrush

As one might expect with such a large group of birds, some, especially those with restricted ranges, are threatened by deforestation. At Bristol we have one of these, the Sumatran laughingthrush G.bicolor. Formerly classed as a subspecies of the White-Crested Laughingthrush, G.leucolophus, it is now placed as a separate species and classed by the IUCN as Vulnerable, possibly Endangered. Part of the problem is that it has been heavily trapped for the local cage bird trade as well as suffering deforestation. At Bristol we have bred them successfully, but at present we do not have a breeding female and are trying to source one to pair with our several males.

Although laughingthrushes are Asian, the international trade in cage birds can result in some turning up in unexpected areas. One of the strangest places they might be found is the Isle of Man in the irish sea, where after escaping in 1995 a few Red-Winged Laughingthrushes G.formosus managed to breed in the wild, and may still possibly be found there. In view of the tiny source population and restricted range, the chances of these surviving or prospering long term seem slim, and they are very unlikely to cross over to either Ireland or the British mainland, but if any birders are visiting the island it my be worth checking to see if they are still around.
Red-Winged Laughingthrush

(images from wikipedia)

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