There are very few Lady Gouldian finches left in the wild. This species that once numbered in the millions is now down to approximately 2500. The reduced number of finches means that there are fewer choices for mates and in Lady Gouldian finches, choice of mate is very important. When LG finches pair up with a mate who has the same head color, 50% of the offspring will be female and 50% will be male. However if finches who have different head colors pair up and produce offspring, 80% of the offspring will be male and the remaining offspring will be female. In addition, fewer (percentage wise) of the female offspring will survive to maturity so in effect, the pairing of mis-matched heads will result in almost all male offspring.
A diminishing population of birds means that there are fewer choices of mates and a greater probability that couples will end up with male and female having different head colors. Unless something is done to reverse this trend, the wild population of LG finches may eventually end up being all males.
By the way, the experiments that were conducted to study the effects of head color used magic markers to color bird head feathers. This enabled the researchers to use the same individual birds while varying head colors in an attempt to find out why the numbers of LG finches are plummeting.
We have a beautiful flock of Lady Gouldian finches at Pandemonium. We hope to have a web cam up and running soon so that you can see them in real time.