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Blue Little Corellas
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Note: Images copyright Lauchie Dunn. Used with permission.


Update - 14 July 2009

A conclusion regarding the cause of this blue colouration has been posted on the blue birds index page.

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Corellas - an Australian parrot

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Corellas are large Australian parrots. There are three species in Australia including the Little corella (Cacatua sanguinea), Long-billed corella (C. tenuirostris) and Western corella (C. pastinator).

Other similarly sized parrots in Australia include the sulphur-crested cockatoo (C. galerita) and galah (Eolophus roseicapilla) - both of which are found in Sydney along with the Little Corella.


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Blue corellas?

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In July 2009 a reader contacted me to ask whether I might know anything about unusually coloured corellas on the Central coast. A work colleague had taken several photos of several birds and had come to him because he was a keen birdwatcher. He was stumped and so forwarded the images to me for consideration.

Although a bird-watcher had previously published photos of a pink, grey and white galah-corella hybrid, I had not heard anything about unusual blue birds.


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Ask an expert!

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I obtained permission to forward the photos to a colleague who is an expert in bird rescue and care. He is usually on top of any interesting stories such as unusual blue birds, and true to form, he alerted me to the blue house sparrow which was photographed in April this year.

The person contributing the photos had already contacted Birds Australia who couldn't provide any insights.

However, according to the contributor, the population of little corellas on the Central Coast grew from a small number about 20 years ago. He assumed it was an escaped aviary flock. The population has grown and spread throughout the region.

Only recently has he also started to see long-billed correlas in the mix.


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First seen in 2008

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Although these images were taken recently, Lauchie Dunn first saw blue corellas in the area in 2008. He believes that the ones in these photos are different than the ones he has seen previously and suspects they may be breeding.

Of course, the fact that a blue sparrow has also been seen - just 2 months ago - may detract from the theory that genetics are the sole cause for this unusual blue colouration.

The story is still unfolding on a daily basis as more questions get asked back and forth between the WLMD reader, myself and bird experts.

No doubt this new revelation that the phenomenon has been reported in 2 unrelated species just 2 months apart will stir up some lively debate!


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Some theories

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In the related article on a blue house sparrow I summarised a number of theories on how this blue colouration has come about.

I will reproduce these here, together with a call for submissions of sightings, photos and feathers, but if you've read it before you go, there was also one unusual brown corella in the flock. See below!

What are the options?

In various forums including thylacoleo.com, Cryptomundo, the Daily Mail and my earlier announcement at WLMD, several suggestions have been put forward.

Genetic mutation

Genetic mutation is unlikely to be the explanation in my opinion - but for reasons that could not be known in April 2009. Two months later I was contacted by a WLMD reader with information about blue little corellas (Cacatua sanguinea) photographed north of Sydney.

To have two distinct species both exhibit exactly the same genetic mutation for blue colouration - a change which has never before been documented in the avian world - just 2 months apart would go against an incredible sway of odds.

Possible ... but unlikely.

Cross-breeding with a budgerigar

One suggestion was that the sparrow had cross-bred with a budgerigar (colloquially "budgie") - a small native Australian parrot which has become one of the world's most popular household pets. Blue budgie morphs do certainly exist, but in my opinion a cross-breed between a finch (the house sparrow) and a parrot (the budgie) is also incredibly unlikely.

Dye

Another suggestion is that the bird bathed in some liquid which contained a blue dye of some form. This seems a very reasonable prospect, but with news coming 2 months later of similarly blue corellas at a location several tens of kilometres away some questions need to be asked of this theory:

  • Did the sparrow and corella flock at one point travel to the exact same location to be dyed, despite being photographed tens of miles apart?
  • If not, then what could be found so commonl in the environment that two completely different bird species (of very different sizes) were both exposed to it?
  • If the cause is a dye which is commonly found between Sydney and the Central Coast, then are there other blue birds out there waiting to be photographed?

(If Richard Shears is reading this, I would love for you to make contact and provide an indication of the location of the sparrow sighting so it can be compared with the location of the corellas).

Diet

Feeding carrots to yellow canaries turns them blue. The quality of the shrimp that flamingoes eat affects the intensity of their pink colouration.

Could the blue sparrow - and the corellas - be ingesting something which is producing a blue pigment in their feathers?

If so, this would certainly be noteworthy given the fact that prior to this, there is no known bird species in the world which actually produces a blue pigment in its feathers.

In my opinion, this option seems the most feasible because an item perceived as a food source by a sparrow can easily be perceived as a food source by a corella - despite them belonging to different families.

So the questions are:

  • What could they be eating?
  • How is it entering the environment?
  • Have there been significant environmental changes between Sydney and the Central Coast that has exposed some food source causing this pigmentation?

Mineral exposure

One suggestion is that some metals, sulfer and some salts are commonly associated with the colour blue. Could these birds have been exposed to such a source?

Algae

It is well known that polar bears and sloths can turn green when algae inhabits the hollows in the hair of their fur - but could there be a blue algae which affects feathers?

This also seems unlikely, as by nature algae is a plant having clorophyl - which is a green pigment, not blue.


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A brown corella too!

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It would have been very easy to dismiss this brown bird as simply being stained by mud or dirt. The WLMD correspondent also thought to dismiss it as such, but wrote again today to say that he has seen this bird in the same flock on a number of occasions and he feels the colouration is also a mutation along with the blue.

So where does that leave us with the overall picture of what's going on? Does the blue fade to brown with age? Does the dye theory now hold best?

Would love to hear your thoughts!

Conclusion

At this stage my opinion is that the colouration is diet related. As a few others have commented - we need to get a feather under the microscope!

The hunt is on, and the challenge is out - serious contenders only please...

If you live in New South Wales, between Wollongong and Newcastle, can you keep your eyes open for unusually blue birds of any species?

Please send all reports to me.

If you can take photographs - all the better. If you manage to obtain a blue feather, then please store it in a clean plastic snap-lock bag, and if possible, don't touch the feather. (Use the plastic bag to pick it up).

With your help we may yet make some fascinating discoveries about blue pigmentation in birds!


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