Saturday, 19 March 2011

Greater sooty owl

Tyto tenebricosa

Common name:
greater sooty owl (en); coruja-sombria (pt); effraie ombrée (fr); lechuza tenebroza (es); rußeule (de)

Order Strigiformes
Family Tytonidae

This species is found in the mountain rainforests of New Guinea, in the mountains of south-eastern Australia, and in Flinders Island, off the northern coast of Tasmania.

In the greater sooty owl, males tend to be smaller than females. Females are 44-51 cm long and weigh 750 g, while males are 37-43 cm long and weigh 500-700 g.

In Australia, this species prefers deep, wet gully forests dominated by eucalypts, occurring in drier forest only when hunting. In New Guinea they occur in lowland and mountain rainforest and Araucaria pine forests, emerging into subalpine grassland and alpine boulderfields and ridges at altitudes of up to 4000 m to hunt.

This powerful nocturnal hunter takes some remarkably big prey, mostly arboreal mammals like the sugar glider (Petaurus breviceps) and the ring-tailed possum (Pseudocheirus peregrinus).

The breeding season of the greater sooty owl is variable, but most eggs seem to be laid in January-June. The nest is in a large hollow tree or a cave, where the female remains for several weeks before laying 1-2 dull white eggs. The eggs are incubated by the female for 42. During the whole period the female remains in the nest she is fed by the male who usually brings one large prey item per night. The chicks fledge about 3 months after hatching but continue to be dependent on its parents for another month.

IUCN status - LC (Least concern)
The global population size has not been quantified, but the species is described as probably rare over its very large breeding range. The population is suspected to be in decline owing to ongoing habitat destruction, mostly due to logging and forest clearance for agriculture. Although there is some fragmentation of its former habitat, in some areas the rainforest is rapidly expanding. Overall the species is not considered threatened at present.

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