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Just realize that the barring gene dilutes skin colour; this is the reason it is so difficult to get dark skinned cuckoos. A double dose of barring would be much harder for dark skin than a single dose. This is one of the reasons that the girls' combs are darker; the other is that testosterone makes combs redder.
Just realize that the barring gene dilutes skin colour; this is the reason it is so difficult to get dark skinned cuckoos. A double dose of barring would be much harder for dark skin than a single dose. This is one of the reasons that the girls' combs are darker; the other is that testosterone makes combs redder.