Siblicide In Nature: Study Of Galapagos Seabird Finds Death Can Ensure Specie...( six days apart siblicide occurs about ...)

The question for Anderson, who first began examining siblicide in 1984 among the boobies that nest on Isla Espanola, the Galapagos most southeastern island, was why. Why engage in a behavior that would seemingly condemn the species to extinction? Why lay two eggs if the goal was only one child?

"Siblicide demands an explanation because its close relatives killing each other," Anderson said. "Getting back to Darwin, the question is how could you maximize long-term reproductive success this way?"

He found part of the answer in the boobies poor hatching rates. Masked boobies only hatch about 60 percent of their eggs, even under perfect conditions unlike other species, which hatch about 90 percent of their eggs. An "insurance egg" hypothesis that a second egg greatly increased the chances of reproductive success turned out to be on target. By laying two eggs, boobies decreased their risk of total reproductive failure to about 16 percent.

But what about the violence and the collaboration between parent and child to eliminate the second-born chick? From 1992 to 1995, Anderson and the Wake Forest graduate students taking part in his National Science Foundation study compared masked boobies to a related species, the blue-footed booby. Blue-footed boobies only engage in siblicidal behavior durin
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Contact: Wayne Thompson
thompsow@wfu.edu
910-759-5237
Wake Forest University
6-Dec-1996