Friday, March 08, 2013

Owls (Phylum Chordata: Order Strigiformes) of Singapore

Owls (phylum Chordata, subphylum Vertebrata, superclass Tetrapoda, class Aves, order Strigiformes) are birds of prey which mostly hunt at night. Depending on the species, they may prey on small mammals, birds, reptiles, insects, crustaceans or fish, which they kill with their powerful talons and sharp, hook-like beaks.

Buffy Fish Owl (Bubo ketupu, previously named Ketupa ketupu)
Owls typically have a flat face with large forward-facing eyes and ear holes, allowing them to respectively see in low light and hear their prey clearly. They have a very flexible neck, and can turn their heads almost 180 degrees to look behind their backs (see the one featured above), giving them a good view of the surrounding to look out for prey or danger. However, being birds of prey with farsightedness, they cannot see things near them, and have to use their talons to feel for things that are near, such as their caught prey.

Despite their often big sizes, owls can fly very slowly and quietly - the surface of their flight feathers is covered with a velvety structure that absorbs the flapping sound made by the wings. They are also usually dull-coloured, allowing them to blend in nicely with the surrounding vegetation.

Most owls swallow their prey whole, and the indigestible parts such as the bones and fur will be regurgitated in the form of pellets.

Spotted Wood Owl (Strix seloputo)
While owls are mostly solitary, they can sometimes be seen in small family groups when the juveniles are still too inexperienced to hunt on their own. Interestingly, a group of owls is called a parliament.

Here are the owls that I have photographed in Singapore:

Sunda Scops Owl (Otus lempiji)
The Sunda Scops Owl (Otus lempiji, sometimes regarded as a subspecies of Otus bakkamoena) is perhaps the commonest owl in Singapore. It is the smallest resident owl in Singapore, getting to about 23cm in length. It can be differentiated from the migrant scops owl by its brown eyes and orangy brown feathers. It can be found in both inland and coastal forests, parks and mature gardens. It hunts for insects and small reptiles at night, and nest in tree holes.

Oriental Scops Owl (Otus sunia)
The Oriental Scops Owl (Otus sunia) is a rare migrant in Singapore. It can be differentiated from the previous species by its yellow eyes, greyish or sometimes brownish feathers, and the white, patchy markings on its wings. It is also smaller, growing to about 19cm in length. It has been sighted in Singapore in both primary and secondary forests, forest edges, and wooded rural areas.

Brown Hawk Owl (Ninox scutulata)
The Brown Hawk Owl (Ninox scutulata) is another rather common resident owl, though there are migrants too. It gets to about 30cm in length, and can be seen in the forest and wooded areas in parks and rural habitats. It is usually active just after dusk, and feeds mainly on insects.

Barn Owl (Tyto alba)
The Barn Owl (Tyto alba) is sometimes encountered roosting in buildings and other man-made structures in Singapore, though they can also be found in parks and forests sometimes. This owl can get to about 34cm long, and has a distinctive heart-shaped face. It usually feeds on small mammals such as rats and mice, and sometimes small birds as well. It nests in tree cavities or in buildings.

Spotted Wood Owl (Strix seloputo)
The Spotted Wood Owl (Strix seloputo) is sometimes encountered in forests (especially at the edges) and parks with mature trees. It can get to about 48cm in length, and can be recognised by the dark horizontal lines on a white background on its belly. The wings are marked with numerous white spots. It nests in tree holes, and roosts in the day on trees.

Buffy Fish Owl (Bubo ketupu, previously named Ketupa ketupu)
The Buffy Fish Owl (Bubo ketupu, previously named Ketupa ketupu) can be found in wooded areas near water bodies, such as mangrove forests or the forests near the reservoirs. It can get to about 50cm in length. It has long ear tufts, yellow eyes, and there is a distinctive pale patch above the beak. The belly is covered in pale orangy-brown feathers. It gets active at dusk, feeding mostly on fish, frogs, and crustaceans, though it sometimes also feed on small mammals and birds. It nests in tree holes, and roosts in the day on trees.



References
  • Briffett, C. 1986. A guide to the common birds of Singapore. Singapore Science Centre. 160 pp.
  • Robson, C. 2010. New Holland field guide to the birds of South-East Asia. London: New Holland Publishers. 304 pp.
  • Singapore Birds. Retrieved Mar 8, 2013, http://singaporebirds.blogspot.sg.
  • Strange, M. 2000. Photographic guide to the birds of Southeast Asia. Singapore: Periplus. 398 pp.
  • World Owl Trust. Retrieved Mar 8, 2013, from http://www.owls.org.

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