When I was in Sydney last week I photographed a Little Corella Cacatua sanguinea (a common species endemic to Eastern, North-western and Northern Australia) in Centennial Park. I first saw the bird from behind and was surprised how approachable it was: it wasn’t until it flew up to a tree and turned around that I realised that its beak was hugely deformed.

I’d never seen a bird with such a massively overgrown beak before and thought I ought to do a little research to see what might have caused it. The mighty Google came up trumps - of course - and referred me to something called Psittacine Beak and Feather Disease (PBFD), a viral disease affecting all Old World and New World Parrots. The virus attacks the feather follicles causing progressive feather malformation and necrosis. In later stages of the disease the feathers develop constrictions in feather shafts, cease development early until eventually all feather growth stops. The virus, though, has a reverse effect on the beak and claws: the virus causes massive overgrowth, malformation and necrotic tissue development. “Cracking and peeling of outer layers makes it possible for fungi and yeast infections to take place and complicate matters even more. The necrosis of inner layers of the beak may cause it to break, at which point the bird will be unable to feed.” (Wikipedia)

The disease also has a general immunosuppresive effect on the bird, clearing the way for secondary systemic viral and bacterial infections to develop which are usually the cause of death. Infected birds can become weak and lethargic - hence, I would think, the approachability of this individual - and there is currently no specific treatment for infected birds.

According to Wikipedia: “…cases of PBFD have now been reported on all continents in at least 42 psittacine species, and this is likely to increase. At least 38 of 50 Australian native species are affected by PBFD, both captive and in the wild. In 2004, PBFD has been listed as a key threatening process by the Australian Commonwealth Government for the survival of five endangered species, including one of the few remaining species of migratory parrots, the Orange-bellied Parrot Neophema chrysogaster, of which only an estimated 60 mating pairs remain (as of 2006).”

Serious stuff eh…