Diet of the Yellow-tailed Black-Cockatoo

Yellow-tailed Black-Cockatoos have a diverse diet. They feed mainly on the seeds of native plants particularly in the Proteaceae family (Banksia, Hakea), while larvae of wood-boring insects (in Acacia, Casuarina) can make up a significant portion of the diet; making the Yellow-tailed Black Cockatoo unique amongst parrot species in south-eastern Australia as they can be thought of as an omnivorous cockatoo.

Proteaceae (Banksia, Hakea)

Lambertia formosa (Mountain Devil)

Wood-boring Larvae

Introduced Pines

Buds, flowers, sap and galls have all been reported as being consumed by this species.

Nectar and/or flowers are commonly eaten.

Male YTBC with banksia

These plant species occur in the habitats that YTBC will be frequenting to feed on their staples of Banksia and Hakea etc, i.e. in coastal heath and banksia woodland. It may be opportunistic that they then include flowers/nectar while feeding on seeds and larvae in the area.

Yellow-tailed Black-Cockatoos consume the rich nectar of Lambertia formosa by either squeezing the base of the flower, or tipping the flower up into the beak with their head back, in what could only be described as a drinking action.

YTBC feeding on Lambertia formosa nectar by tipping the flower upside down to pour the nectar out

They seek out the seeds from pine cones of the introduced Pinus radiata. An observation and lab study in the late 1980s confirmed the species extracted fungi and slime mould from under the bark of dead trees (1). These exceptionally intelligent birds know exactly where, when and how to find the food they want, and there is still a lot to learn about them.

YTBC digging into wood

Juvenile Yellow-tailed Black Cockatoos in their first year (dependent on parents) will alternate between staying still and begging – often for long periods of time – and experimenting with self feeding such as with Banksia to (often clumsily) try and extract seed. Often the Banksia infructescence (in the case of B.integrifolia) will not be removed from the tree; rather the bird will attempt to extract seeds without holding it, or pull seeds out if there are open follicles.

Juvenile YTBC with Banksia

Banksia

YTBC has a long, slender bill unlike that of any other black-cockatoos, besides the Baudin’s which is significantly longer but for different reasons. The evolution of the YTBC beak is clearly heavily adapted to their common behaviour of digging deep into hard wood to pull out grubs/larvae deep within branches and trunks of species like Acacia and Casuarina.

Female extracting larvae

But perhaps above all else, it is the Banksia that is the most important plant genus to Yellow-tailed Black-Cockatoos. The distribution range of the genus in eastern Australia is correspondent to that of the birds’ distribution range. Human occupation of the coast has resulted in extensive, widespread and continual clearing and degradation of Banksia and other YTBC habitat.

YTBC are adept at locating standalone individual Banksia trees planted in suburban gardens, to which they will often return annually.

Most Banksia species in the south east provide a year-round food source for Yellow-tailed Black-Cockatoos, as their seed-containing follicles mostly remain closed for long periods of time, until fire or death of part of all of the plant stimulates the opening of the follicles and release of the seeds.

YTBC flying with banksia

An exception to this is Banksia integrifolia (coast banksia) which does not hold on to its seed. When the seed is mature the follicles soon open for seed release, with no seed being held on this plant at the end of each season. This usually occurs in the late spring into early to mid-summer. Yellow-tailed Black-Cockatoos have an obvious instinctive pattern of behaviour to descend on coastal areas in flocks during this time specifically to access the seeds of B.integrifolia, although they will also consume some other foods while in the area (e.g. larvae).

However, B.integrifolia is clearly their primary and specific purpose for moving to specific locations along the coast for this short window of time every year. Some pairs will have dependent young at this time, who can often be seen experimenting with how to eat Banksia seeds. Some years I have noted some arriving earlier in the season and consuming the flowers of B.integrifolia.

YTBC eating Banksia integrifolia flower

YTBC flying with Banksia integrifolia flower

Once the concentration of B.integrifolia seed pods have diminished to the point where there’s not enough to sustain the flock or warrant their effort, the number of birds reduces and flocks eventually move on.

This is a widespread species in eastern Australia occuring in many different habitat types from the mountains to the coastal fringe and importantly, they are capable of travelling vast distances. Little to nothing is known about their nesting and movement habits in NSW. Regardless of where they are, the Yellow-tailed Black Cockatoo seeks out specific types of inverterbrates in the form of wood-boring larvae. At times it’s possible that these larvae are not just a supplement to the diet, but could be a dominant part of the diet. This species has a beak shape that has evolved to carry out to this very task in a methodical and expert manner.(2)


References
1. Fungal feeding by Yellow-tailed Black-Cockatoo
2. Cockatoos, Matt Cameron CSIRO Publishing 2007

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