Eastern Grass Owl - Tyto longimembris
Formerly considered to be conspecific with Tyto capensis
Calls - Tyto longimembris
[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: Upperparts are dark brown with pale spots, with buff bars in
the wings, which can appear bluish-grey in flight. The underparts are creamy white to pale
buff with some brown spots. The facial disc is white and may have pale buff marking. There
is a brown mark in front of each small brown eye, with the edge of disc dark brown on top
but buff on sides and bottom. The legs very long compared with other Tyto species (about
fifteen per cent longer), with feathering on the lower parts reduced to a few bristles.
The feet are greyish and the Bill is light brown. The legs are carried horizontally in
level flight but part lowered during take-off, landing and aerial manoeuvres. They can be
distinguished from all other Tyto Owls by their long legs with protruding feet in flight,
long wings, and terrestrial habits. The female is larger than the male.
Size: Length females 35-38cm (14"-15"), males 32-36cm
Wing Span up to 116cm (45.5"). Weight up to 450g
Habits: Nocturnal, but will sometimes fly during the day. This species is adapted for life on the ground, and normally hides in long grass. My 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 (1.6-1.7") by 29-32mm (1.1-1.25"). 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: The Grass Owl Has been recorded in coastal areas from
around the Manning River in northern New South Wales northwards through Queensland and to
Arnhem land but most records are from north-east Queensland. A second population, usually
widely scattered, occurs through the arid inland areas of Queensland and the Northern
Territory. Usually very rare but may become locally and temporarily common during
irruptions of Long-haired Rats inland or Cane Rats in coastal regions. Recorded as vagrant
in all mainland States, usually after successful breeding season inland followed by
population crash in prey species. Grass Owls are also found in the Philippines, Sulawesi,
lesser Sundas, possibly Fiji, Tatwan, southern China, parts of South-East Asia and India.
They also occur discontinuously in New Guinea.
Distribution of the Eastern Grass Owl Tyto longimembris
Original Description: Jerdon, Thomas Claverhill. 1839. Madras Journal of Literature and Science, 10, p. 86.
T. l. longimembris,
T. l. chinensis,
T. l. pithecops,
T. l. amauronota,
T. l. walleri,
T. l. baliem,
T. l. papuensis
Page compiled by Deane P. Lewis. Page last updated 2012-08-13
OwlPages.com Owl Species ID: 010.170.000