Long billed Corella

To: "Michelle Plant" <>
Subject: Long billed Corella
From: Beth Mantle <>
Date: Fri, 25 Apr 2008 10:01:19 +1000
Hi Michelle,

I can't say definitively why there is increased prevalence at this time of year, but I suspect it is related to the large numbers of juvenile parrots that begin seeking (are forced into?) independence around this time. Many of the cockatoos that come in to the wildlife hospital are young birds, and it is almost certain that the disease is transmitted by the parents to young parrots while they are in the nest.

It is possible that, as the birds mature, the disease progresses as well such that recently fledged birds are in the most acute stages of the disease. The PBFD virus causes immune deficiency (amongst other things), rendering the young parrots susceptible to all sorts of other diseases as well. I think that contact with flocks of conspecifics would permit further transmission of the virus before the diseased birds become too ill to fly or feed.

I have been told (and I have been unable to substantiate this) that the virus is always present in many individuals (both adults and juveniles), but if the bird becomes stressed then the virus becomes problematic. I guess in some ways this is like a few other viruses that affect humans (herpes and HIV). I don't know what the stress triggers would be, but I imagine leaving the nest, finding food and water, and interacting with flocks of conspecifics may qualify.

It appears that Dr Gary Cross from the University of Sydney was researching the disease over 15 years ago, and according to a website ( ) a vaccine was developed. This vaccine was used to innoculate populations of OBP's (see , and apparently those birds are still resistant to the virus (which is good news). I have no idea if any further research is being conducted, but I think the increased prevalence (and fatality) in juvenile parrots would make an interesting PhD project for someone.

As I said in my first email, I'm not an expert by any stretch of the imagination. My background is zoological (frogs, in fact) so I'd be very interested to hear from anyone else out there on Birding Aus who may know more about PBFD.

Beth Mantle

H: 02 6287 7860
M: 0407 174 427

On 25/04/2008, at 9:14 AM, Michelle Plant wrote:


Any indication/suggestions of why there is increased prevalence?


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