None of my Araucanas had what I'd call a distinct "laughing crow". However, my personal theory is that this trait comes from the tufts gene. This gene not only causes tufts, but can result in other defects in the head and neck. Sometimes birds even have holes in their throats. It's not hard to imagine that these throat defects can also result in abnormal crows. It may be that the original Indians selected for these abnormal "laughing crows" for whatever cultural or religious reasons. But now they aren't selected for, so have died out, or are very rare.
That's why there is additional mortality associated with one copy (heterozygous) of the tufts gene. Two copies of the gene is lethal to the developing chick embryo and they die in shell.
Rosalyn
That's why there is additional mortality associated with one copy (heterozygous) of the tufts gene. Two copies of the gene is lethal to the developing chick embryo and they die in shell.
Rosalyn