The Eyes Have It

My ‘Bird Nerd’ column in the latest Australian Geographic Magazine (Issue 159) is all about variations in colouration and patterning in birds caused by the presence or absence of certain pigmants.

The blacks and browns, in particular, are caused by melanin, and the lack of this pigment can cause a partial (piebald) or total loss of an individual’s dark patterning.

The two main terms that describe these anomalies are albinism and leucism, and both conditions can cause very similar results. Both are genetic and inherited. Leucism, though, causes a lack of the pigment cells that produce melanin, while albinism causes the production of actual melanin pigment itself to be reduced or absent.

So how can we distinguish between the two conditions without the assistance of a cellular biologist? Well, the trick to telling them apart is all in the eyes.

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