The eclectus parrot (Eclectus roratus) has already been considered an anomaly in the animal kingdom. Males and females in this species look so different that for a very long time researchers believed that they actually were two different kinds of parrots. Now, it has been discovered that the eclectus possess a much more interesting trait. They have the ability to choose the sex of their offspring.
ANU professor Rob Heinsohn has been studying this species for most of the past decade, and by studying that really means climbing thirty meters up in the air and perching on a wooden platform. He discussed one particular bird well known for possessing this trait. “There was a famous parrot in Chester Zoo that produced 30 sons before switching to produce 20-something daughters. Nobody knew why, but it told us that these parrots have some way of controlling the sex of their offspring.”
Heinsohn discovered that the tree hollows that are used for nesting are not very common, and when a female picks out a tree for breeding she will not leave the entire time she is nesting for a fear of losing her spot. This will require her to depend on the male for food.
This is where it starts to get interesting and completely gruesome. Heinsohn and colleagues discovered that the female would usually lay two eggs. They also discovered that both eggs were normally viable; however, when they would return to the nests they would only find one chick.
Heinsohn then said, “Then we worked out that the missing chick was always a male. In an act of sex-specific infanticide, the females were tossing the males overboard. We saw beak-shaped peck marks on the backs of their head or neck when we found their little corpses.”
They determined this was the result of the female trying to speed up the nesting process because females leave the nest much sooner than males. This way they would still have one chick survive, but could get out of their sub-standard nesting situations that resulted from floods.
The parrots are now the only other animal that exists that kills their offspring on the basis of gender. Heinsohn also said that they may have found conclusions to why this occurs in nature, but they are still not sure why it happens in captivity.