http://sciencenow.sciencemag.org/cgi/co ... 2009/320/2
In case you guys can't read it here's basically what it says:
-a study was initially done on the gender outcomes of offspring when the parents were the same head colour (red:red and black:black) and when they were opposite head colours (red: black and black:red).
-they found that same coloured pairs produced approximately equal amounts of male and female offspring and opposite coloured pairs produced ~82% males.
-to find out if this was due to genetics or if the female was choosing the outcome (apparently when pairs are mismatched less female offspring survive to adulthood anyway so producing more males would be beneficial) they coloured some of the red-head males black and the black-head males red.
-the outcome was still an equal sex ratio for same head coloured birds (even if the male wasn't really the colour he appeared) and an overabundance of male offspring at 72% when the males were the opposite colour of the female (again even when he wasn't the colour he appeared).
-this is clear evidence that the hens are capable of CHOOSING the genders of their young! What is still left to answer is HOW they are able to do this.
The only thing I didn't like about this article was the picture of the red and black heads next to each other stating "When these two finches mate, they'll produce an overabundance of sons" - both the birds in the picture are males.
The actual journal article is only available if you have a subscription - which luckily my school does - so if anyone wants to read the actual article PM me and I'll send you a copy on Monday.
EDIT: link hopefully fixed
