Featured Research

from universities, journals, and other organizations

Looks Matter To Female Barn Swallows

Date:
October 4, 2005
Source:
Cornell University
Summary:
Even after they have paired with a male, the female North American barn swallow still comparison-shops for sexual partners. And forget personality, the females judge males by their looks: the reddish color of the males' breast and belly feathers.

Rebecca Safran, a Cornell postdoctoral researcher in ecology and evolutionary biology, removes a captured barn swallow from a net in Groton, N.Y.
Credit: Photo Kevin Stearns/University Photography

"The bad news formale swallows is the mating game is never over," said lead authorRebecca Safran, who conducted the study while a Cornell postdoctoralresearcher in ecology and evolutionary biology, and in the CornellLaboratory of Ornithology. "It is dynamic and continual. This issomething that most humans can relate to -- think of how much time andmoney we spend on our looks and status long after we have establishedstable relationships."

Barn swallow (Hirundo rusticaerythrogaster) males have a wash of reddish-chestnut color from theirthroats to their bellies, and this color varies among birds from verypale red-brown to a dark rusty-red. Like many songbirds, half of allmale barn swallows typically care for at least one young chick that wasactually fathered by another bird. The researchers used this widespreadphenomenon of cheating to test the factors that may keep a female barnswallow faithful to her mate. Sometimes males even rear an entire nestof illegitimate young.

After all pairs had laid their first setof eggs, Safran removed the eggs so that the females would mate again.Before the females chose their mates for their second nest, Safrancaptured the males and randomly assigned them to one of threetreatments. She either painted their throats, breast and belly featherswith a red marker to enhance their feathers to match the darkest -- andmost attractive -- males in the population, or left them alone orpainted them with a clear marker to ensure that results were not biasedby the coloring process. Then she let the pairs breed again. Sheconducted comparative DNA tests on the offspring from the first andsecond nests.

In the research, all 30 females remained sociallypaired with their original male mate, but they were sexually activewith other males. The males with enhanced color fathered asubstantially larger percentage of offspring in their second nests.Males whose color was unchanged fathered the same number or fewerchicks than they had in their first nests. "The study shows that thefemales are paying close attention to these signals and that theyrespond quickly to changes in their mate's appearance," said Safran.

Thereddish breast and belly feathers indicate a male's quality, such ashis health, status or ability to raise young, Safran speculates.

Theactual cue that female barn swallows use to assess potential matesdiffer according to regional tastes. For example, classic studies haveshown that in the very closely related European barn swallow (H.rustica rustica), males with long tail feathers attract more mates.Although many previous studies have investigated mating patterns inbirds and other animals, this is the first study of its kind tometiculously rule out biases such as age, size and initial variation insignals of male quality, like coloration, and to demonstrate thatmate-selection decisions are continual and dynamic. The results of thestudy have implications for the evolution and upkeep of showyornamental traits -- such as a peacock's tail or a deer's antlers --that are costly for males to maintain but give them an edge over rivalmales. "If females are assessing mates on a day-to-day basis, itexplains why males continue to maintain costly ornaments even when theymight appear to have served their purpose," said co-author IrbyLovette, assistant professor and director of the Cornell Lab ofOrnithology's Evolutionary Biology program.

"Our goal is now tounderstand how certain males keep a better plumage than others," saidKevin McGraw, Cornell Ph.D. '03, one of the co-authors who is now anassistant professor at Arizona State University in Tempe. "Factors likeultraviolet radiation from the sun, soiling and even feather degradingbacteria are known to affect the color of bird feathers once they aregrown, and perhaps the best males are those who spend more timepreening and protecting their plumage."

The paper's otherco-author is Colby Neuman, Cornell B.S. '05. In early September, Safranbegan a new position as a postdoctoral researcher at PrincetonUniversity. Supporters of the study included: the National ScienceFoundation, the American Association of University Women, the AmericanOrnithologists' Union and the Animal Behavior Society.


Story Source:

The above story is based on materials provided by Cornell University. Note: Materials may be edited for content and length.


Cite This Page:

Cornell University. "Looks Matter To Female Barn Swallows." ScienceDaily. ScienceDaily, 4 October 2005. <www.sciencedaily.com/releases/2005/10/051003233317.htm>.
Cornell University. (2005, October 4). Looks Matter To Female Barn Swallows. ScienceDaily. Retrieved September 30, 2014 from www.sciencedaily.com/releases/2005/10/051003233317.htm
Cornell University. "Looks Matter To Female Barn Swallows." ScienceDaily. www.sciencedaily.com/releases/2005/10/051003233317.htm (accessed September 30, 2014).

Share This



More Plants & Animals News

Tuesday, September 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Earth Has Lost Half Its Vertebrate Wildlife Since 1970: WWF

Earth Has Lost Half Its Vertebrate Wildlife Since 1970: WWF

Newsy (Sep. 30, 2014) A new study published by the World Wide Fund for Nature found that more than half of the world's wildlife population has declined since 1970. Video provided by Newsy
Powered by NewsLook.com
Dolphins Might Use Earth's Magnetic Field As A GPS

Dolphins Might Use Earth's Magnetic Field As A GPS

Newsy (Sep. 30, 2014) A study released Monday suggests dolphins might be able to sense the Earth's magnetic field and possibly use it as a means of navigation. Video provided by Newsy
Powered by NewsLook.com
How To Battle Stink Bug Season

How To Battle Stink Bug Season

Newsy (Sep. 30, 2014) Homeowners in 33 states grapple with stink bugs moving indoors at this time of year. Here are a few tips to avoid stink bug infestations. Video provided by Newsy
Powered by NewsLook.com
California University Designs Sustainable Winery

California University Designs Sustainable Winery

Reuters - US Online Video (Sep. 27, 2014) Amid California's worst drought in decades, scientists at UC Davis design a sustainable winery that includes a water recycling system. Vanessa Johnston reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins