Red-tailed Black Cockatoo

SPECIES Red-tailed Black Cockatoo
TAXONOMY Calyptorhynchus banksii graptogyne
STATUS Least Concern (Redlist.org)

Also known as: Banks’ Black Cockatoo; Great-billed cockatoo

The Red-tailed Black Cockatoo was first illustrated in 1770 during the ‘first voyage of discovery led by Captain James Cook on the British Royal Navy vessel HMS Endeavour’ as it was beached on the Australian mainland for repairs after running aground on the Great Barrier Reef. The bird was named in honour of Royal Society Naturalist Joseph Banks, who was instrumental in assembling the team of naturalists for this voyage.

Distribution
Native to mainland Australia, the Red-tailed Black Cockatoo has five recognised subspecies that occur in isolated populations in a variety of habitats. Most subspecies are observed in large populations becoming more prolific in dryer regions. However, the south-eastern Red-tailed Black Cockatoo (Calyptorhynchus banksii graptogyne) has adapted quite specifically and once flourished in a geographic region isolated by impassable terrain in south eastern South Australia and south western Victoria. 

Habitat
Most subspecies can be found in forests and woodland where eucalyptus, casuarinas, acacias, and banksias are found. They can also be seen near cultivated farmland and regional towns. Their distribution is less reliant on a specific food source and populations continue to flourish. 

The south eastern Red-tailed Black Cockatoo (C.b. graptogyne) has fully adapted to exist amongst specific vegetation and became isolated because of this. Their region once held vast areas of the native Desert Stringybark, Brown Stringybark, and Buloke trees. Although a reduction in habitat has occurred, this subspecies continues to rely on this food source as it has done for thousands of years. 

Feeding
Feeding in pairs or in flocks, most Red-tailed Black Cockatoo dine on the seeds of eucalyptus, casuarina, acacias, and banksias. They will also harvest fruit, berries, nectar, flowers, and insects and their larvae. They will forage in the trees or on the ground. With their unusually small yet extremely strong beak, seeds are extracted while still green from their pods; tearing it open whilst they hold it with one claw. With most subspecies, there is a variety of food sources to choose from.

However, the south eastern Red-tailed Black Cockatoo has evolved to being an ecological specialist, feeding almost entirely on the freshest green seeds of the Desert Stringybark, Brown Stringybark, and the Buloke trees. The flowering pattern of these specific trees determines their feeding grounds, and has greatly led to their isolation. As they look for the youngest of seed pods, they will fly further distance from their nests placing the chick at risk. They will exploit these food sources until depleted.

Behaviour
Outside of breeding season, Red-tailed Black Cockatoos are often seen in large flocks (up to as many as 500) and sometimes alongside other cockatoos such as the Yellow-tailed Black Cockatoos, particularly in the northern regions and when food sources are in abundance. They are noisy, gregarious, and mainly arboreal. The northern subspecies will be seen foraging on the ground. The flock will return in the evening to the same location for roosting, often in the same spot for several months and usually alongside a river or stream.

Monogamous by nature, they will leave the flock for mating. They are described as dispersive, meaning that they will leave the area where they are born. Their migration patterns are seasonal and focussed on food sources. 

Appearance
These cockatoos are the largest of the Australian parrots. They weigh up to 920 grams with a length of up to 60 centimetres. They can achieve a top speed of 70 kmh in flight.

The male is predominantly glossy black, with a full crest that protrudes past his grey bill. He lives up to his name with striking red-orange panels across the tail that are more visible from underneath. 

The female is unusual as a bird species as she is more colourful than her male counterpart however her black plumage may appear slightly more dull overall.  Her underbody is barred with pale orange-yellow scalloped black feathers, her breast feathers are tipped in colour, her tail has orange-yellow panels with black bars, and she has yellow spots on the head, neck, and wings. She has an off-white bill. Both sexes have dark brown eyes, legs, and feet.

Juveniles up to age three resemble the adult female.

Reproduction
Adults reach full maturity at about four years of age. Red-tailed Black Cockatoos are monogamous, and if they do lose their partner they may choose not to mate again. They can nest at any time of year, but usually this is more a case when food supplies are abundant.

They look for naturally occurring deep tree hollows in very tall, ancient trees. They line the hollow with fragments of wood chips or dust. They will enter the nest tail first.

The female will lay one single egg (sometimes two), and will incubate it for up to 30 days. The male will bring her food during that time. Once the egg hatches, the female will look after the young hatchling. As he grows, both parents will take responsibility to feed him. Throughout the first ten weeks of life, the chick remains silent. However once the feathers grow and he is getting close to fledging, the noise begins. This process takes around 100 days and can be taxing on the parents to find additional food sources. This period can also be risky as the female may leave the nest in search of food. 

When he is ready, he will take flight with his parents alongside. The juvenile will continue to depend on his parents for another six months. 

Threats
There are threats to the species that affect all regions: most notably is bird smuggling as this is one of the more iconic cockatoo species. Also significant to their survival is habitat loss, as the loss of old growth trees reduces nesting opportunities.

The south eastern Red-tailed Black Cockatoo suffers in addition because it is so specialised in its choice of food. Although populations of the species occur Australia wide in numbers of more than 100,000 --- this specific subspecies has been recorded at less than 1500 in recent years. It is the loss of their habitat consisting of the Desert Stringybark and the Brown Stringybark being reduced by 50%, and the Buloke tree by up to 90%. These tree species continue to be cleared to make way for agricultural activities. Nesting sites (old growth eucalyptus with hollows) within farming paddocks have been cleared to improve pasture. 

When nesting does occur, scarcity of food sources cause the parents to forage further afield which leaves the nest exposed. Populations of adults are reducing, and there is becoming an imbalance in the ratio of male to female. Some scientists are declaring that this subspecies is nearing an extinction level event due to the demise of their habitat.

An effort in providing artificial nesting hollows, the protection of trees, and encouraging natural regeneration and planting for the future are just some of the methods being implemented. Monitoring and support in recovery is now on the agenda of leading organisations. 

Updated on 5 May 2021