Gouldian Finches occur in two morphs. Red heads or Black heads. Red-headed females prefer red-headed males – and black prefer blacks. In the small populations it is not always possible for the finches to chose their own type. When they cross the results are not good. However, a “hybrid” female will always have less viability than “hybrid” male. The stress of mating the “wrong”kind makes the Gouldian Finch able to regulate the outcome producing more male “hybrid” offspring which has better viability. Read Grrl Scientist fascinating account how the females do this.
