In April 2009 Richard Shears, a journalist with the Daily Mail (UK) published photographs of a blue house sparrow (Passer domesticus) which visited his garden in Sydney, Australia.
In July 2009 a reader of Where Light Meets Dark made contact - quite unaware of the blue sparrow - to enquire about blue little corellas (Cacatua sanguinea) photographed by his friend on the Central Coast, just north of Sydney.
Whilst investigating these two incidents, information came to light about a third species of bird seen with blue plumage - the Australian White Ibis (Threskiornis molucca)
Finally, in June 2010 another reader sent through photos of another blue sparrow - this time from Canada.
All things considered, it seems as if the colouration has been caused by a blue dye.
|2010||Sparrow||Photos||Canada||1 bird photographed|
|2009||House Sparrow||Photos||Sydney, NSW||1 bird photographed; possible sighting of 2nd bird|
|2008, 2009||Little Corellas||Photos||Central Coast, NSW||Numerous birds photographed on numerous occassions; also 1 brown bird|
|2008||Australian White Ibis||Photos||Sydney||Three sightings between June and November 2008. Photographed twice. Probably 1 bird, with blue feathers being replaced by white ones during moult|
In the pages above you'll read of various theories, including genetic mutations, cross-breeding, diet and dye.
Wildlife Management Officer Geoff Ross, with the Parks & Wildlife Group - Department of Environment and Climate Change (PWG/DECC) has this to say about the blue ibis in particular:
"We monitored this bird for a while around Sydney (it hasn't been seen for some time now). In the past we've seen others with dye on the feathers. There are sites in or around Sydney , where somehow these birds come into contact with a dye. Most have been waterbirds, Pelican, Ibis etc. I think the dyes are water soluble because they seem to fade after rain. Usually when the dyed birds show up there's a lot of discussion to find out if anyone is using dye tags, in this case no one knew of any dye tagging programs. Ibis particularly are commonly found at waste centres, tips and other refuse areas and are often exposed to a variety of human refuse. The colouration does not appear to affect their condition, they seem to be able to feed and carry on as usual." (personal communication, 14/7/09)
One more point to note is that although the ibis was commonly seen in large aggregations of ibis, none of the other birds was blue. This tends to favour the theory that the colouration is due to immersion in a dye, rather than ingestion. Likewise the blue sparrow was seen in a normally coloured flock. Although the blue corellas appeared in a flock, the colouration varied significantly from bird to bird and in the case of the last blue corella on that page, appears to have been splattered on the bird.
Regarding the brown corella on the same page, Ross says "I have seen Corella, and Sulphur-crested cockatoos in Sydney suffering from a disease called Psittacine circoviral Disease or "Psittacine Beak & Feather". The brown discolouration on the feathers appears to be a very early symptom of the disease."