CREATURE FEATURE

by Kerri-Lee Harris

When I heard the plaintive calls of Glossy Black-Cockatoos this morning, I had no inkling of the treat that was in store.

We are fortunate to live in a forest regularly visited by these remarkable cockatoos. They are certainly not an everyday sighting for us, but we do see them a couple of times a month on average, throughout the year.

But today there were nine! Unprecedented! We typically see pairs or groups of three. Last week we had a group of six visit - and thought that extraordinary. But nine!! I think  'gob-smacked' best describes our reaction.

As usual, they were feeding in tall Allocasuarina littoralis trees in an area we call 'the gully'. This is the patch of forest they favour. We rarely see Glossies feeding on the higher parts of the property, even though 'Black Sheoak' (A.littoralis) grows throughout. The gully is a shallow depression with a relatively undisturbed middle storey dominated by Allocasuarina littoralis and Banksia serrata. 

This video that Paul made highlights how much time and effort the birds devote to each fruit. It takes 2-3 minutes to completely empty the 'cone' of its many tiny seeds. And the Glossies are very thorough. We've collected the trash from beneath the tree and tried in vain to find any remaining seeds. 

Mother of two (?)

We witnessed something else quite extraordinary today – what looked to be an adult female Glossy feeding two very demanding teenagers. According to all that I've read, Glossies typically lay just one egg. Either this was a very accommodating aunt, or she and her partner had an unusually productive season in 2017. 

The benefit of photos! At the time, I really couldn't be sure what was going on. The birds were flapping, and calling, and actually seemed to be fighting - or at least squabbling. But a closer look at this series of shots reveals quite a different story. 

The adult is behind (facing the camera), while the two juveniles are in the foreground. In a flurry of wings, tails and beaks, she first feeds the one on the left, then the one on the right. It was all over quite quickly, and the birds went back to the slow process of chewing cones.

It is normal for juveniles to remain partly dependent upon their parents until the following breeding season. This mother was certainly feeding the young ones – but she also seemed to be driving them away. Perhaps she'll nest again soon (?)

Update: several readers have commented that this might be an adult male, rather than a female. Apparently the small amount of yellow on the face does not mean this is a female - males can have a bit of yellow feathering too. Other readers noted that the young ones seem full grown. They certainly have very little tail barring left. However, their behaviour and overall smaller size does strongly suggest, to me, that they're teenagers. Whatever was actually going on here might remain a mystery ... and perhaps that just makes the event all-the-more intriguing! Thank you to everyone for your feedback and comments.

Siesta

The birds were very active early, calling and flapping about as they clambered through the sheoak canopy. A few hours on and they were simply resting, perched more securely on eucalypt branches, chatting quietly or preening. 

Yellow feathers and whale tails

Seeing so many birds together reminded me how individual the colouring is on females. Some have extensive yellow patches, while others have almost none. The 'mother of two', for example, seemed to have just a couple of yellow feathers. She could almost be mistaken for a male. 

And that made me wonder if ecologists could use this as a key to individual identity. Like they do the under tail markings of humpback whales. Just a thought ...

Further reading

Glossy Black-Cockatoo, NSW Scientific Committee (2008): a brief overview of Glossy biology and conservation status 

The Black-Cockatoo Project Facebook page of Daniella Teixeira, including descriptions of her research into the calls of Glossy Black-Cockatoos

For more stories from the forest, visit Life in a Southern Forest

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