The Owl Pages
Google+
Follow Me on Pinterest

Eastern Grass Owl - Tyto longimembris

 
Calls - Tyto longimembris
Female at nest Female at nest accepting food from male © John Young
Chicks begging © John Young

Introduction: The Eastern Grass Owl is a medium-sized owl with no ear-tufts and long legs.

[For help with terms used in the description, see parts of an owl. For general characteristics common to most owl species, see owl physiology.]

Description: The facial disc is white for males or with a fawn-coloured wash with most females. The eyes are blackish-brown and the bill whitish-cream.
Upperparts are dark brown with yellowish-ochre flecks and small whitish spots. The wings are very long with three dark bars on the primaries, and wing-coverts similar to the back. The tail is relatively short, with 3 or 4 dark bars.
Underparts are white to whitish-cream with scattered small dark spots. Legs are feathered whitish to about two-thirds down the tarsus, with the lower third and the toes bare, and coloured yellowish-grey. The claws are blackish-brown.

Size: Length 32-42cm. Wing length 273-360mm. Tail length 114-139mm. Weight 250-582g. Females are larger and heavier than males.

Habits: Nocturnal, but will sometimes fly during the day. This species is adapted for life on the ground, and normally hides in long grass. May breed semi-colonially or groups up to several dozen may hunt in the same area.

Voice: Appears to be more silent than the Barn Owl, the normal call being a hissing scream similar to a Barn Owl. In loudness and harshness it is about midway between a Barn Owl and Masked Owl.

Hunting & Food: Numerous species of rodent have been recorded as prey, long haired Rat and Cane Rat being the most common. Grass Owls, even more than Barn Owls, are specialist hunters of small rodents and rarely take any other prey. Even though they weigh much the same as Barn Owls, their wings are considerably longer, reflecting their method of hunting which is done entirely in flight and never from perches. Hunting is by low, quartering flight followed by a quick plunge into the grass when prey is detected. In typical Grass Owl areas, prey is hidden from sight and located and taken through the combined use of hearing and the very long legs.

Breeding: Grass Owls probably breed at any time of year if conditions are favourable but, in coastal parts of northern Australia, laying usually occurs between March and June. The nest is on the ground in dense tussocks of grass or sedges, particularly bladey grass, usually well away from trees. The nest is a flimsy platform of grasses which soon becomes trampled and obliterated. It is enveloped in grasses and is approached by a series of tunnels, usually at least three, which the Owls make by pushing their way through on foot. One of these is normally the main one and the grass at its entrance becomes flattened from repeated landing and departures. In the nest, 3-8 dull white eggs are laid. they are slightly more pear-shaped than other Tyto Owls and measure 40-44mm x 29-32mm. Incubation is thought to be around 42 days (assumed to be similar to the African Grass Owls). The young have a first down of white and second of warm golden brown. Fledging is at about 2 months. Long before this, the female stops brooding them and they walk away from the nest to hide in the grass, returning at night when the adults bring in food. All young appear to fledge in dark plumage, indistinguishable from adult females.

Habitat: Tall grasslands and swampy country. Dense, well-established tropical grasslands, particularly with bladey grass or sedges and around cane fields. Also desert grasslands at times of plagues of long haired Rats. Although rare, they have colonial tendencies and up to 30 have been recorded in an area of under 100 hectares. They are rarely seen unless flushed and are generally thought to perch only on the ground but there have been sightings of birds perching on topmost spray of young pines.

Distribution: From India to Vietnam, North Malay Peninsula and Southeast China, Taiwan, Philippines, Sulawesi, Flores, Southeast New Guinea and Australia. Also found in New Caledonia and Fiji.

Distribution of Eastern Grass Owl - Tyto longimembris
Distribution of the Eastern Grass Owl Tyto longimembris

Status: Common.

Original Description: Jerdon, Thomas Claverhill. 1839. Madras Journal of Literature and Science, 10, p. 86.

Subspecies: T. l. longimembris, T. l. chinensis, T. l. pithecops, T. l. amauronota, T. l. walleri, T. l. baliem, T. l. papuensis

References:

Boyer and Hume. 1991. "Owls of the World". BookSales Inc
del Hoyo, Elliott & Sargatal. 1999. "Handbook of the Birds of the World: Barn Owls to Hummingbirds". Buteo Books
Duncan, James R. 2003. "Owls of the World: Their Lives, Behavior and Survival". Firefly Books
Hollands, David. 1991. "Birds of the Night". Reed Books
König, Claus & Weick, Friedhelm. 2008. "Owls: A Guide to the Owls of the World (Second Edition)". Yale University Press
König, Weick and Becking. 1999. "Owls: A Guide to the Owls of the World". Yale University Press
Mikkola, Heimo. 2012. "Owls of the World: A Photographic Guide". Bloomsbury
Trounson, Donald and Molly. 1996. "Australian Birds - Simply Classified". New Holland Publishers

Page Information:

Page compiled by . Page last updated 2013-08-21

OwlPages.com Owl Species ID: 010.170.000