Aussie Finch Forum

How do they determine the sex of young?

My males always have a bit of black in the breast bar area when they fledge.

Might not be perfect but it's worked so far.

Also it is fawn from two parents that aren't fawn (if it is fawn, might be someting else but I don't know what)

Peter

I meant how do female birds determine the sex of their young? Q to finchbreeder.

Hi Tiaris, sorry to butt in -

Birds are classified as having a ZW gender determination, as opposed to the mammalian XY. In birds, some insects (and i think i remember the komodo dragon?) the female is ZW and the male is ZZ - so offspring's gender is determined by the female, in ovum.

Justin

jluna wrote:Hi Tiaris, sorry to butt in -

Birds are classified as having a ZW gender determination, as opposed to the mammalian XY. In birds, some insects (and i think i remember the komodo dragon?) the female is ZW and the male is ZZ - so offspring's gender is determined by the female, in ovum.

Justin

Getting offtopic but why in some finches if thats the case does female bring out more or full nest of males if she is the only one in the aviary?? wouldnt you think that she would determine that more hens are needed if she can determine the sex of young??

I don't think he means it is a conscious decision by the female as to which ones are to be what sex, but rather that it is the female's genetic composition which determines the sex of all her offspring. ie. whether she sheds a male or female ovum (egg) ?? I thought the sperm played an equal part in determining sex of progeny.

That's right - the hen bird contributes the W gene, which produces males - obviously not consciously, any more so than a human male can prescribe the gender of his baby, though it is the sperm which does this job. Off-topic again, but I believe in the wild, Cuban finches are known to regulate numbers post-hatching, i.e., killing off males or females according to what is 'needed' to balance the population...

Aggressive male Cubans certainly can clear the deck of young males in captivity too if they are allowed to do so. Fortunately their temperament seems to be a very heritable trait. Young males bred from passive/tolerant fathers are also tolerant in my experience (Also partly determined by environment though ie. stocking rate, aviary size, etc.)

Yes, Charcoals are recessive so all young are splits. I would think it common for Fawn or Marked White hen zebra's
to pop out of nests with normal 'looking' Grey parents sourced from pet shops. Same with Pieds (recessives are worse).
You can breed a line for several years and just have them pop out so nothing would surprise me.

"the hen bird contributes the W gene, which produces males - obviously not consciously, any more so than a human male can prescribe the gender of his baby"
Exactly what I was aluding to. So if you want hens use a hen who produces daughters. And if you want sons marry a man who has brothers.
LML