Powerful Owl (Ninox strenua), Barking Owl (Ninox connivens), Masked Owl (Tyto novaehollandiae) and Sooty Owl(Tyto tenebricosa).

All four of the NSW threatened forest owls listed above are present throughout the Central Coast and Lake Macquarie regions. These are collectively referred to as the large Forest Owls. These owls are all forest dwellers, but vary in micro-habitat requirements and general ecology. The calls of these large forest owls can be heard throughout the bushland reserves, National Parks and State Forests within the region. The large forest owls are the top level nocturnal predators of the forest and woodland areas. Their continued presence in certain localities is principally dependent on the presence of suitable foraging habitat, prey species and hollow-bearing trees for roost and nest sites.

The Powerful Owl and the Barking Owl are commonly referred to as ‘Hawk owls’ due to their visual similarity to hawks. The Masked and Sooty Owls have the typical heart shaped facial disc, characteristic of the 'Barn Owl' group. The Southern Boobook Owl (Ninox novaeseelandiae) and the Barn Owl (Tyto alba) also occur locally but are not considered to be part of the Large Forest Owl group.

Conservation Status

All four owls are listed as vulnerable species under Schedule 2 of the NSW Threatened Species Conservation Act 1995. 

These species have small population sizes due to low reproduction rates, high juvenile mortality, large home ranges and decreasing areas of habitat.

Description

Hawk Owls (Ninox Owls) - The Powerful Owl is the largest of Australia's owls, measuring up to 60cm. The Barking Owl measures up to 40cm. Both owls display hawk like features and are generally brown. The Powerful Owl’s breast has wavy brown bars or chevrons on a white background. The Barking Owl’s breast is coarsely streaked brown on a white background. Both owls have large yellow eyes and strongly built yellow feet with feathered legs. The males of both these owls are larger than then the females.

Barn Owls (Tyto Owls) - The Masked Owl is the largest of this group with a length of up to 50cm. The Sooty Owl is slightly smaller at 45cm. Both owls display the flat heart shaped facial disc. The Masked Owl’s colouration varies across from almost a pure white breast with dark spotting to a rufous brown with dark spotting. The Sooty Owl is mostly dark brown-grey with sooty eye rings and disc, pale grey breast and fine white spotting above and below.  The Masked Owl has powerful feet which are fully feathered to their toes. The female of both these owls are noticeably larger than the males.

Other Characteristic Features

Special features: All owls have special wing feathers adapted to allow them to fly silently. This allows them to hunt without being detected by prey species with sensitive hearing.

Pellets: Owls regurgitate hair, feathers and bone of their prey in the form of pellets which are usually found below their nesting hollows or roost sites. Expert examination of these pellets can identify what prey species that have been eaten. This may help in the identification of the owl species and other fauna in the local area.

Calls: All four owls have a distinctive call, knowing the call is the easiest way to identify owls.

• The Powerful Owls call is a strong slow “whoo-whoo”.  Visit the NSW Threatened Species website to hear the call.
• The Barking Owl makes a quick dog like “wok wok”, it is also known, at breeding time, to make a loud blood curdling ‘human like’ piercing scream. Visit the NSW Threatened Species website to hear the call.
• The Masked Owl call consists of a low pitch drawn out rasping “cush-cush-sh-sh” or “quair-sh-sh-sh”. Visit the NSW Threatened Species website to hear the call. 
• The Sooty Owl call resembles the sound of a loud descending whistle (or falling bomb) followed by rolling cricket like, chirruping trills. Visit the NSW Threatened Species website the hear the call.

Diet

All four owls are nocturnal hunters, relying on their ability to detect prey species by sound and vision. The following is a list of favoured prey.

• The Powerful Owl preys on larger arboreal mammals, such as the Yellow-bellied Glider and Greater Glider, and larger bird species.
• The Barking Owl is predominantly a bird eater, but frequently feeds on large insects during the pre-breeding season.
• The Sooty Owl is a generalist, mainly preying on arboreal and terrestrial mammals, birds and insects.
• The Masked Owl is a specialist predator of terrestrial mammals and occasionally arboreal mammals, such as Sugar or Squirrel Gliders.

Life History & Reproduction

• These four owls are monogamous, forming life long pair bonds and are generally sedentary, occupying large permanent home ranges. The female incubates the eggs and is fed on the nest by the male.
• The Powerful Owl and Barking Owl breed throughout the winter with a breeding period of 3 to 4 months, usually rearing up to 2 or 3 chicks. Powerful Owls breed in large hollows such as broken off trunks within large eucalypt trees. Barking Owls prefer open trunk hollows usually within live trees.
• The Sooty and Masked Owls breed between January and October. Particular breeding times are related to the availability of food. Both species require large tree hollows in which to lay eggs. The breeding period is usually 3 months. The Sooty Owl raises 2 chicks and the Masked Owl up to 3 or 4 chicks each season.
• Fledgling mortality for all these species of forest owls is high.

Preferred Habitat

Each species utilises various habitat types within their home range.

• The Powerful Owl has a home range that varies with quality of habitat and density of prey, usually about 1000ha (1km²), within tall moist eucalypt forests containing large trees and a dense mid storey and a fern understorey.¹
• The Barking Owl has a home territory around breeding or roosting sites of approximately 300 hectares with a foraging (hunting) range of 1000 hectares (1km²). Preferred habitat is more open forest areas with a mosaic of vegetation with open understorey.¹
• The Sooty Owl has a home range that varies with quality of habitat and density of prey, usually about 300 to 800ha. This species prefers denser vegetation in tall moist eucalypt forests, palm gullies and rainforest areas in coastal regions.¹
• The Masked Owl has a home range of approximately 1000 to 1200 hectares with a core area of about 150ha. The Masked Owl prefers open forest areas with open understorey.²

Daytime Roosting

Sooty and Masked Owls roost throughout the day in tree hollows. The Powerful and Barking Owls roost throughout the day in the thick foliage of mid storey trees, often within gullies.

Where these Species can be Found

The distribution of large forest owls throughout the Gosford, Wyong and Lake Macquarie district is wide spread. These owls are known to occur in local bushland areas and conservation reserves of the National Parks and State Forests. They are likely to inhabit margins of residential areas especially those located near bushland areas.

Gosford: Bouddi National Park, Nardoo Rd, Peats Ridge; Lisarow, Matcham, Kincumber Ridge, MacMasters Beach.

Wyong: Wadalba Wildlife Corridor, Wadalba; Bruce Crescent, Warnervale, Palmdale Valley.

Lake Macquarie: Wallarah National Park, Wallarah; Gradwells Road, Dora Creek; Mt Waring Reserve, Ridge Road, Kilaben Bay.

Where are these Species Habitat Protected?

Gosford: Brisbane Water, Dharug & Bouddi National Parks, Kincumba Mountain Regional Reserve.

Wyong: Wadalba Wildlife Corridor; Olney, Wyong, Watagan and Ourimbah State Forests.

Lake Macquarie: Lake Macquarie State Conservation Area; Awaba & Watagan State Forests; Wallarah National Park.

Threats to Survival

• Habitat clearing and fragmentation.
• Removal of tree hollows.
• Intensive logging.
• Bushfires and/or non-prescribed bushfire regimes.
• Collisions with motor vehicles.
• Secondary poisoning from eating rats poisoned brodifacoum-based rodenticides.

Management Issues

Long term habitat management approaches should be directed towards maintaining connectivity within and between large patches of forest to link areas of suitable habitat and to ensure the protection of prey by maintaining understorey and ground cover habitat within bushland areas.

Recovery Plans have been prepared for these large forest owls by the NSW Department of Environment and Conservation.

• Support protection and management of bushland containing owl species.
• Encourage and plan for tree retention, particularly habitat trees on private land.
• Revegetation of riparian and creekline habitats, for movement and foraging opportunities.
• Retain old growth forest, including the ground cover, such as fallen logs to maintain habitat for prey species.
• Increase community awareness and involvement in owl conservation of the community through local environment network.

Useful Web links:

• Birds Australia Website - www.birdsaustralia.com.au
• Department of Environment and Climate Change www.environment.nsw.gov.au
• The Owl Pages - www.owlpages.com/owls.php?location=Australia
• The Scribbly Gum - http://www.abc.net.au/science/scribblygum/april2005/

Further Reading:

• Fleay, D. (1968) Night Watchmen of Bush and Plain, Jacaranda Press.
• Hollands, D. (1991) Birds of the Night, Reed Books, Sydney.
• Newton, I; Kavanaugh, R; Olsen, J; Taylor, I. (2002) Ecology and Conservation of Owls. CSIRO Publishing, Victoria.
• Pizzey & Knight (2003) The Field Guide to the Birds of Australia 7th edition. Harper Collins Sydney.
• DEC Recovery Plan for Large Forest Owls Powerful Owl (Ninox strenua), Sooty Owl (Tyto tenebricosa), and Masked Owl (Tyto novaehollandiae) October 2006.
• DEC Draft Recovery Plan for the Barking Owl (Ninox connivens) February 2003.

Bibliography:

1. Higgins, P.J. (Ed) 1999. Handbook of Australian, New Zealand and Antarctic Birds, Volume 4: Parrots to Dollarbird. Oxford University Press, Melbourne.
2. Kavanagh & Murray 96, Emu 96, 250 – 257.