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“The public needs to be better informedabout psychological reactions to cata-strophic events and the potential risk ofavoiding certain risks,” Gigerenzer says.

Psychologist David G. Myers of HopeCollege in Holland, Mich., made much thesame point in December 2001, when hepredicted that a terrorism-inspired boostin automobile use would lead to about 800additional car-related deaths in 2002.Monthly data on 2002 road fatalities havenot yet been released.

Excess car deaths attributable to 9/11had already begun to accumulate by thetime Myers made his prediction, Gigeren-zer finds. Airline data confirm large dropsin passenger miles for the last quarter of2001. Monthly miles driven rose nearly 3 percent in October, November, andDecember, much greater increases than inany months earlier that year. Moreover, inthe last 3 months of 2001, the largest traf-fic increases occurred on rural interstatehighways, indicating that long-distancetravel surged.

Gigerenzer also consulted federal dataon fatal car crashes. The average number ofdeaths in each month of the year remainedconsistent from January 1996 through Sep-tember 2001. Fatalities then substantiallyrose in the final 3 months of 2001.

Gigerenzer may have tapped into anextreme example of people’s tendency torely on emotional reactions to situationswhen estimating risk, remarks psycholo-gist Paul Slovic of Decision Research, anonprofit research corporation in Eugene,Ore. This mental shortcut often works well,but it causes people to overestimate the like-lihood that especially frightening eventswill recur, Slovic proposes.

“It is perfectly normal to fear purpose-ful violence from those who hate us,”Myers says, “but smart thinkers will alsowant to check their intuitive fears againstthe facts.” —B. BOWER

Cheap Taste?Bowerbirds go forbargain decor

When male spotted bowerbirds collectsticks and other doodads to wow females,these natural interior decorators don’tsearch for the rare showpiece, according toa new study.

Biologists have wondered whether male

bowerbirds try to show off rare or costlytreasures, says Joah R. Madden of theUniversity of Cambridge in England.However, in recent tests of male prefer-ence in ornaments and their availability,no fancy tastes showed up, he and AndrewBalmford of University of Sheffield inEngland report in an upcoming Behav-ioral Ecology and Sociobiology. Itemsmost appealing to females in earlier testsalso turned out to be commonplace.

Among bowerbirds, which are native tothe South Pacific, males stake out and dec-orate courting spots, and females shopamong the local displays. In the spottedbowerbird (Chlamydera maculata) of Aus-tralia, males build two parallel walls ofsticks that females can enter. Males strewthe surroundings with shells, berries, twigs,and other knickknacks. When a femalestops by, the male breaks into a song-and-dance routine.

Bowerbird lore includes tales of rareornaments. A 1990 report, for example,said Archbold’s bowerbirds decorate withplumes from a bird of paradise species thatmolts only two of the big feathers a year.

To systematically check decor rarity,Madden and Balmford focused on 121 kindsof ornaments that spotted bowerbirds usedin three areas of Queensland. The research-ers sampled the areas to see how frequentlyeach potential decoration turned up.

Madden had already shown that, amonga bower’s adornments, many little greenberries from a Solanum ellipticum bushbest predict courtship success. Yet theseberries ranked within the 11 most common

decorations in the new survey. Many bower decorations, such as metal

tags, didn’t show up in the sampling. YetMadden and Balmford found no correla-tion between such rarity and an item’spower to predict successful mating, asdetermined in the previous work. Whenoffered sets of objects to use as ornaments,the male bowerbirds showed no preferencefor novelty.

Neither difficulty of collecting items ornor the need to refresh the display gaveany clue to effectiveness of a decoration.Solanum berries, for example, aren’t par-ticularly heavy compared with other orna-ments, and among five decorative fruits,the berries tied for first in holding theirlooks.

A long-time bowerbird researcher, Ger-ald Borgia of the University of Maryland inCollege Park, acknowledges that flirtationsignals don’t have to be costly but questionsMadden and Balmford’s analysis. “They aretrying to assert a negative, which is difficult,”he says. He says he would like more analy-sis of such factors as color preferences.

Gail Patricelli of Cornell University saysof the new study, “This is interesting, as acontrast to what satin bowerbirds do.” Theyfavor rare, blue ornaments, and males stealthem from each other, so a blue-adornedbower signals that its holder has been enter-prising and tough, she says.

Among spotted bowerbirds, bowerdecorations signal social standing, saysMadden. The number of green berriesreflects the rank of a male; otherwise,neighboring males attack. —S. MILIUS

SCIENCENEWSThis Week

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BACHELOR PAD A male spotted bowerbird typically decorates his courtship structure with white shells outside the entrance and a scattering of other treasures.

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