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The Honolulu Advertiser
Updated at 3:30 a.m., Wednesday, May 28, 2008

Albatross females share chick-rearing duties

Advertiser Staff

A UH-Manoa doctoral candidate and her colleagues have found that the Laysan albatross employs a strategy called reciprocity, where unrelated females pair together and take turns raising offspring.

Zoology doctoral candidate Lindsay Young found that on Oahu, 31 percent of nests are female-female pairs. Female pairs raise fewer chicks than male-female pairs. Since albatross can only raise one chick each year, females stay together for multiple years for each to reproduce. This unusual strategy may explain why Laysan Albatross are successfully re-colonizing islands.

The findings by Young and her co-authors have been published in the Royal Society journal Biology Letters in a paper titled, "Successful same-sex pairing in Laysan albatross."

Unrelated same-sex individuals pairing together and cooperating to raise offspring over many years is a rare occurrence in the animal kingdom, according to a UH news release. Cooperative breeding, in which animals help raise offspring that are not their own, is often attributed to kin selection when individuals are related, or altruism when individuals are unrelated, according to the release

The study documents long-term pairing of unrelated female Laysan albatross (Phoebastria immutabilis) and shows how cooperation may have arisen as a result of a skewed sex ratio in this species. Thirty-one percent of Laysan albatross pairs on Oahu were female-female, and the overall sex ratio was 59 percent females as a result of female-biased immigration.