Is this a rare sighting?

[Connie Mier]

Found this albino yellowcrown nightheron today. Has anyone ever seen or heard of this in nightherons?
Connie
[IMG][/IMG]

[John Chardine]

Hi Connie- Very nice to see and a great picture, and yes, albinism is extremely rare. I'm no geneticist but as far as I understand it the condition is caused by a recessive gene. This means that it is not expressed unless an individual has two copies of the gene, one from each parent. If two carriers of the gene produce offspring there is a one-in-four chance that one will be albino. So if the gene is rare in the population to begin with, and then you have to get two genes together in two parents, and even when you do only one-in-four offspring are albino, you can see how rare the trait can be in the population. Wikipedia provides a figure of 1 in 17,000 humans is albino, which seems higher than in other animals. Because the trait is only expressed rarely, natural selection does not get a chance to act on it very often so the gene floats around in the population, occasionally popping up.

[Connie Mier]

John, thank you for the very informative reply. I guess this is likely a once-in-a-lifetime encounter. Awesome.
Connie