RE: Leucistic/Albino New Holland Honeyeaters in Geelong

Hi All,

Today, down at the Barwon River in Geelong,
Victoria, there were TWO Luecistic ( i think the word is) New Holland Honeyeaters
in a group of about 10 or so.

They were feeding quite happily with
the other NNHE's, and i only saw one bird get a bit nasty with one of the
birds. 

I found it odd that there was not one,
but two birds with this rarity. Would it be possible that these birds are
twins? If not twins, you'd think that these birds would be somehow related???
 Or could this just be a case of the dietary intake of the flock,
with two birds producing leucistic offspring?

If anyone has any theories or info on
what causes this characteristic in birds, i'd love to hear  about
it. 

I've posted a couple of pics here:

http://www.deakin.edu.au/~pfuller/albino.html
  
I think the two pics posted here are
of the same bird...i may update the sight with pix of the other bird if
i manage to work out the difference between them.

Cheers, 

Peter