Aussie Finch Forum

Hi all.

I have an unexpected fledgling (yesterday) that looks like it could be fawn.

This works for me if Fawn is autosomal recessive but the odds are really against it being sex linked (although always possible)
The father (charcoal) has had seven hen chicks and until this one all were NG to look at.

This last fledgling (one of 3) is an accidental nest with a daughter, while I was away at Xmas.
Stangely too, none of the three are charcoal.

Everything I read says sexlinked.

Could this be wrong? could it be something else?


Thanks

Peter

Fawn is sex-linked recessive.

I presume NG means normal grey.
If the father is split for fawn, then he will throw a percentage of fawn daughters, not sons.
The prportions you read for the offspring of any given pairing are only percent probabilities, not exact and binding fractions of offspring.
He - presuming he is the father - is split.

OK, thanks.

one in eight seemed too far away from the 50:50 probability.

I'll wait till it's older & see what it might turn into.

Regards

Peter

The possible result percentage of throwing a Fawn hen is not 50/50 but only 12.5%.
Therefore, your 1 out of 7 or eight is not that far off the mark. Likewise, 12.5% of
cockbirds will/should be split for Fawn. This is all dependent on there just being one
pair of zeb's in a flight or cabinet. If more than one pair, anyone could be the parent/s.

Ok, so there's more to it than a simple sex linked recessive gene then?

I would have thought with a split Cock & a normal hen

50% cocks & hens normal.
25% fawn hens
25% split cocks.

50% of the hens would be fawn. (25% of all chicks) (as a probability only)

Does the charcoal have an impact?

Sorry to go on.......

Peter

Charcoal is autosomal recessive, so all young will also be split charcoal.
Your breakdown for fawns looks ok to me.

Thank you

Peter out.

Normally you should get 50/50 fawn and other hens as I said earlier. You mentioned getting 7 other hens plus the one fawn hen. This is well below the average but not impossible. Gordy's proportions are correct if you are talking cocks and hens together. As I read from your first post, you mentioned 7 hens then the fawn.
Your male is split fawn assuming he is the father

The father could be any male in the avairy, not necessarily the one who is feeding the hen/chick. Good Zeb cocks will feed any bird that seems to require it. The 50-25-25 ratio is correct for the fawn sex linked mutation. If the cocks previous nests have been heavily female this is up to his previous mate/the mother of the young hen, as birds and moths are the only creatures know where the sex of the young is determined by the female.
LML