That is so strange.
If you find the answer from another site, please let us know here. And thanks for looking after the hummers all these years. :)

Piebald is it's own kind of mutation. Albinism is the inability to produce melanin at all. Usually the albino gene is near completely recessive, in that one normal gene paired with one albino gene looks normal. In some few cases, that one albino gene atrongly impacts the ability to produce melanin, so the normal, melanin producing gene is unable to mask the effect. This results in an organism that shows diluted melanistic color, melanin present but reduced from normal. The thing is, it's evenly distributed, not blotched. Blotched white/normal is called piebald.

An interesting looking bird. Good capture!