Kookaburra sibling rivalry gets rough
By Susan Milius
Kookaburras may have the most famous laugh in the bird world, but life for their nestlings doesn’t sound particularly funny.
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The chunky Australian kingfishers usually lay three eggs in a nest. The older two hatchlings commonly kill the youngest, reports Sarah Legge of the Australian National University in Canberra. In the September Behavioral Ecology and Sociobiology, she describes two ways that older sibs do in the youngest.
First, Legge observed the two elder siblings attacking the third sibling outright. They hacked at the youngster with a hook on their upper beaks, which Legge calls “a rare example of a morphological specialization for sibling rivalry.” The youngest birds died of such injuries in a third of all the nests she observed. The other big danger for the youngest kookaburra comes from slow starvation. In a fifth of Legge’s nests, the older siblings hogged the food.