Peculiar Silver-eye

[Jake]

I have not asked permission to share these images, so here's a link to pics of a very interesting fellow
https://ebird.org/view/checklist/S47305449

[Jim Kirker]

The upper mandible looks about twice the length of the lower, but no wider than normal. The bone grew too long and perhaps is still growing. It must limit what it can feed on, but presumably the feeder provides it with sugar. I wonder what the cause is, genetic or an acquired metabolic effect ?

[Jake]

Definitely something f*** with its keratin production (based on that, I'd vote that this is genetic). Note that its nails are looking wild too; one of the middle ones looks like it may have gotten caught on something and ripped/broken off

[Jim Kirker]

Yes, keratin overgrowth. Fits better with the normal bill width. I agree nails are too long too. It's looking like "Avian Keratin Disorder".
There is an article in the OSNZ September 2016 Newsletter (I found it by googling "avian keratin disorder osnz").