Sunday, 7 August 2016

Nesting Glossy Black Cockatoo & Powerful Owl


Powerful Owl male
Two of our more uncommon birds, Glossy Black Cockatoo and Powerful Owl, have successfully raised chicks in the Brisbane area.

Glossy Black Cockatoo - male feeds female at nest tree
A pair of Glossy Black Cockatoos are raising a single chick on a private property on MacLeay Island in southern Moreton Bay. Thanks to Glen Ingram for the tip off about the nest, the location of which is under wraps.

Glossy Black chick at nest hollow
According to Glen, the adults return to the nesting tree - a tall Scribbly Gum Eucalyptus haemastoma - each evening between 15 and 30 minutes before sunset. The male feeds the female regurgitated Allocasuarina orks before the female flies to the nesting hollow to feed the chick, whose head is visible at the entrance by that time. The youngster and the female then disappear into the hollow.

Female Glossy Black with chick
When we were there, the female then emerged and both adults flew to a nearby Allocasuarina littoralis to feed, but Glen says she usually remains in the nest as night falls. Between one and three pairs of Glossy Black Cockatoo nest on McLeay Island each year.

Female Glossy Black with chick
They are believed to be part of a population of between 10 and 20 birds that inhabits nearby North Stradbroke Island. The cockatoos are sometimes seen flying over open water between the islands.

Bush Stone-Curlew
At Glen's home nearby, his resident Bush Stone-Curlews were in their usual fine form in the garden.

Tawny Frogmouth
Over on the mainland, a pair of Powerful Owls have again bred successfully, this time raising two youngsters at the traditional site of J.C. Slaughter Falls Reserve in the Brisbane suburb of Mt Coot-tha. Andrew Stafford joined Glenn and I for a visit to the owls. We found a Tawny Frogmouth perched near the owls' nest tree; how it survives predation by the owls is something of a mystery.

Powerful Owl female
The two adults and two chicks were all perched within easy view in exactly the same spot where I last saw Powerful Owl at this site in the mid-2000s. The size difference between the adults was apparent with the much larger male.

Powerful Owl chick
One chick was also significantly larger than the other, suggesting one of each sex; it is unlikely that the size difference was due to varying ages.

Powerful Owl chick
Powerful Owls have been present and nesting at the Mt Coot-tha site since 1987; I wrote an article about the birds for The Sydney Morning Herald back in 1990. It is quite a feat that they have managed to continue finding sufficient food not only to survive but to raise young regularly, although they do not nest every year. It is likely that they forage well into nearby suburbs in search of Common Ringtail Possums, a dietary staple. As well, flying-foxes have to some extent replaced prey such as Greater Gliders, which they presumably have eliminated locally - as they appear to have done at other sites in the Brisbane area. Yet Sugar Gliders have been on the dietary list at the same spot for more than 20 years ago; perhaps the owls have a wider area of dispersal for feeding than is thought. They have nested in several different trees but all the nesting trees have been within a few hundred metres of each other.

Pink-eared  Ducks
While in Brisbane I called in to Minnippi Parklands, where a pair of Pink-eared Ducks were of interest.

Cotton Pygmy Goose
On matters waterfowl, back on the Sunshine Coast I saw 20 Cotton Pygmy Geese on Wappa Dam. This is the largest concentration of this species that I've encountered on the coast.

Spotted Harrier
Elsewhere on the coast, Spotted Harrier continues to show nicely in the canelands near Bli Bli.

Spotted Harrier



1 comment:

  1. Incredible birds Greg, I have recently noted numerous Glossy Black Cockatoos flying over the house again-something that hasn't occurred since their nearest large food source was cleared. Still out looking for those owls, but with no luck!

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