Biology and breeding of the Red-tailed Cockatoo. PART II

February 3rd, 2016 | by Julie and Barry Blanch
Biology and breeding of the Red-tailed Cockatoo. PART II

Read also the first part of this article:

Biology and breeding of the Red-tailed Cockatoo. PART I


Northern Samueli

(Calyptorhynchus b. samueli) AKA the inland subspecies

Throughout the central interior of Northern Territory, western Queensland and New South Wales inland areas there are three main large fragmented populations of the Northern Samueli. Most of these areas are scrub or riparian woodland along the major river systems and including tributaries’ of the Darling River. The land is relatively flat with gentle slopes and receives mainly summer rainfalls between 220- 700 mm annually.

Summer temperatures reach 23°C- 36°C with much cooler overnight winter temperatures down to -1°C- 7°C. The Northern are nomadic throughout their range and return to the breeding sites a month before nesting in the same area each year. The nesting sites are usually in the larger hollow eucalypt trees – Brigalow and Eucalyptus Coolibah (Black box) woodlands and scrub growing on the flood plains and along the water courses or in the wet-lands. Breeding begins in March through until June. Young fledge after 87 days and remain with the parents for up to 12 months.



Large broad acre farming grain crops grown all year round provide an easily obtained food source for the birds. They can be known to ruin the crops as they ripen and at times can be regarded as pests. Some farmers resort to illegal shooting and poisoning to preserve their living.


Wheatbelt or Coastal Wheatbelt Samueli

(Calyptorhynchus b. samueli)

The western Wheatbelt Samueli subspecies are found inhabiting vast areas of the coastal areas of Western Australia covering approx. 600klm from north south and 300-400 klm wide distance. The large area ranges from the Port Hedland in the Pilbara region down over the Gascoyne River skirting the eastern area near Geraldton around the western side of Lake Moore to the wheat areas near Northam.

The vegetation ranges from mallee scrub, spinifex heathlands and eucalyptus woodlands. The eucalyptus of the ‘Wheatbelt’ includes Salmon gum Eucalyptus salmonophloia, Wandoo E. wandoo, York gum E. loxophleba subsp.loxophleba and Red Morrel E. longicornis along with casuarinas and coastal banksia.

The areas in the Coastal or Wheatbelt Samueli habitat experiences variations in the climatic conditions from an arid and tropical climate in the north reducing to a moderately arid tropical climate down to the milder tropical in the southern parts of their range. In the Pilbara region summer temperatures between December – May range between 32°C – 45°C with average yearly 270mm rainfall from the irregular heavy tropical thunderstorm downpours. High rainfalls recordings 400mm- 500mm   occur on the mid coastal areas.



Wheatbelt samueli cock (c) Julie and Barry Blanch


The Wheatbelt Samueli have been known to breed either February – March or May – June depending on the area they inhabit and the winter temperatures that range from 0°C inland up to 10°C on the coastal areas. Nests are usually found as high up as possible in hollows of vertical tall trees. Many of the trees chosen for a nesting in are isolated dead large trees in cleared forest areas and used for many years.

The breeding age of the female Wheatbelt can be at 3 yrs. while the young 2 year old male birds have been known to fertilise eggs without mature plumage. Pairs while being monogamous do not mate for life. During the incubation period the hens leave the nest morning and evening time to be fed by the male twice a day. The females only brood the young chicks for a couple of weeks after hatching and leave the nest during the daytime due to the extremely high day temperatures. Both parents feed the young chicks in the nest and continue to feed the young fledglings and juveniles for several months.



(Calyptorhynchus b. graptogyne)

This Red tail is often referred to as the South Eastern Redtail and is listed as being endangered with an approximate population of only approx. 1000 birds remaining in the wild in a small region found in south-eastern Victoria and into a small neighbouring part of South Australia. The Graptogyne are the smallest of the subspecies.

Graptogyne flock with > 100 birds during the autumn and winter but are usually seen in small family parties or alone during the breeding season. Maturity is reached in the birds 3rd year and males have been known to fertilise eggs even though they haven’t obtained their full adult plumage.



Graptogyne female (c) Julie and Barry Blanch


Breeding commences in the wild during September through until early January although they will breed in any season depending on the conditions and availability of other factors such as nesting sites, food sources or extreme seasonal changes. Juvenile birds continue to be fed up to 6 months after fledgling and resemble the adult female. Females are the most brightly marked and coloured of all the subspecies despite having an overall brown-black dull feathers while the males are a glossy black highlighting the vivid red panels in the tail.




author: Julie and Barry Blanch, Australia

Title photo: (c) Lubomir Tomiska


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