Press Release 06-130
Bird Moms Manipulate Birth Order to Protect Sons

Hormonal changes affect egg laying and development

A mated pair of house finches (Carpodacus mexicanus) and the mites that infest their nests. Credit and Larger Version

September 19, 2006

According to a new study by scientists at the University of Arizona, female house finches are able to change their hormonal makeup to ensure male birds hatch later, grow faster and spend less time in the nest than their sisters. The strategy is nature's way of protecting vulnerable male hatchlings that appear to be more sensitive to nest-marauding mites than their female siblings are.

Once breeding female finches are exposed to mites, their bodies make hormonal changes that affect the order of egg laying and accelerate development of their sons while they're still in the egg. The scientists say that helps make sure male chicks are exposed to mites for a shorter period and allows both the sons and daughters to survive long enough to leave the nest.

And not to worry, the researchers say, the male chicks that grow up during mite season end up just as big as ones from the mite-free time of the year.

The work, which is scheduled to be published in the early online edition of the Proceedings of the National Academy of Sciences the week of Sept. 18, was funded by the David and Lucile Packard Foundation, the National Science Foundation and the Silliman Memorial Research Awards.

To read the University of Arizona news release go to http://uanews.org/cgi-bin/WebObjects/UANews.woa/7/wa/SRStoryDetails?ArticleID=13101.

-NSF-

Media Contacts
Mari N. Jensen, University of Arizona (520) 626-9635 mnjensen@email.arizona.edu
Leslie Fink, National Science Foundation (703) 292-5395 lfink@nsf.gov

Principal Investigators
Alexander Badyaev, University of Arizona (520) 626-8830 abadyaev@email.arizona.edu

Related Websites
Alexander Badyaev Web site: http://www.u.arizona.edu/~abadyaev/

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering, with an annual budget of $6.06 billion. NSF funds reach all 50 states through grants to over 1,900 universities and institutions. Each year, NSF receives about 45,000 competitive requests for funding, and makes over 11,500 new funding awards. NSF also awards over $400 million in professional and service contracts yearly.

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