Australasian Science: Australia's authority on science since 1938

Parrot Infanticide Favours the Female Chicks

By Stephen Luntz

Eclectus parrots are one of only three species known to engage in sex-selective infanticide.

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Aspects of the remarkable sex-selection behaviour of maternal Eclectus parrots have been explained in Current Biology, but tantalising mysteries remain.

The parrot, which is native to Cape York and Papua New Guinea, will sometimes kill its offspring. “It’s interesting in itself because infanticide is weird – why do you have babies and then kill them?” asks lead author Prof Robert Heinsohn of the Australian National University.

While it is not unknown for animals to kill their young, Eclectus parrots are, with humans and antechinuses, the only species known to engage in sex-selective infanticide.

It took Prof Heinsohn and his team 10 years to produce a sufficient data set to be confident that they understood the birds’ logic.

Female parrots always lay two eggs in a season and are solely responsible for guarding the nest and caring for the young. However, they rely on males to provide them with food.

Heinsohn observed that infanticide only occurs when one baby is male and one female. In nearly 20% of such cases the mother will kill the male. Whether she does depends on the quality of her nest.

The parrot nests in hollows, but Heinsohn says: “Some are really good for nesting in, some are poor. The poor ones have a habit of flooding in heavy rain, drowning the chicks or eggs inside.”

A mother with a bad nest will sometimes...

The full text of this article can be purchased from Informit.