When Dad's Not a Looker, Mom Compensates

Sept. 27, 2006 — -- It may be true that the early bird gets the worm, but it turns out that it's also true that it doesn't hurt to be the ugly bird either.

New research shows that a female house finch who gets stuck with a dull male can make up for some of his shortcomings by embedding an extra dose of hormones and antioxidants in the yolks of her eggs.

It's one of those miracles of nature that we never knew was there until a few years ago when scientists found that a female can deposit different amounts of nutrients in her eggs to give her offspring a better chance at survival.

No one's yet sure how she manages to do that, but until now scientists believed the female would naturally favor eggs that had been fertilized by a male with gorgeous red plumage, because he got that color by being good at getting food, and thus would be a better provider.

"We found completely the opposite," says Kristen Navara, lead author of a report on research conducted at Auburn University, published in the November/December issue of Physiological and Biochemical Zoology.

Navara is a reproductive physiologist, and she is now a postdoctoral fellow at Ohio State University's College of Medicine and Public Health. Co-authors are Alexander V. Badyaev at the University of Arizona, Tucson, and Mary T. Mendonca and Geoffrey E. Hill of Auburn.

"There is the thought that the best-looking males potentially have the best genes, so theoretically the female would want to invest in the offspring with the best genes," she adds.

Nope.

She says her research shows that a female tries to compensate for having a dull male by doing what she can to enrich her eggs with the things the offsprings will need for growth and development. She calls it "compensatory strategy," which is "an attempt to compensate for the lower quality of a male."

That strategy seems to be working, judging by the population explosion among house finches despite the fact that they live rather hazardous lives. They like to live around people, so there's lots of things to fly into, like cars and windows and cats, and they suffer from a number of diseases, particularly pink eye.