Our penchant for rarity could threaten conservation efforts

April 22, 2009

Rare plant and animal species are like rare stamps or coins: they are perceived to be inherently more valuable to people, whatever they look like. Researchers Elena Angulo and Franck Courchamp, from Université de Paris-Sud, have found that people are more attracted to species labeled "rare" than those labeled "common" even when they do not know which species are involved. The study, published April 22 in the online, open-access, peer-reviewed journal PLoS ONE shows that this irrational value conferred to unknown items only for the sake of rarity is both an asset and a threat for conservation.

It has been recently suggested that the value people place on rarity could lead to the extinction of rare species as we are willing to pay the high costs of exploiting the last individuals. Many hobbies, such as ecotourism or the keeping of exotic pets, may cause this effect, known as the anthropogenic Allee effect. However, this theory relies on the untested assumption that people do indeed value rarity.

To assess whether people really do value rare species more than common ones, Angulo and colleagues set up a website where visitors were told they could view one of two slideshows of images: either one containing images of "rare species" or one containing images of "common species." No other information about the featured species was provided. When visitors downloaded a slideshow, a progress bar appeared, showing what percentage of the slideshow had been downloaded. The bar filled up after six minutes but the file still appeared to be downloading and did not open. Visitors could cancel the download at any time and were taken to an error page, which would then link them back to the slideshow download page to try again (although the slideshows never opened).

The researchers measured: a) how attractive the rare slideshow was to the visitors (based on the proportion of visitors who downloaded the rare slideshow as their first or only choice), b) how long visitors were prepared to wait to download each slideshow and c) how perseverant visitors were (how many times they tried to download each slideshow before giving up). Even though visitors knew nothing about which species each slideshow contained, more people opted to view the rare species slideshow. Visitors also waited longer for the rare species slideshow to download before giving up than they did for the common species slideshow and after the download failed, they made more attempts to download the rare species slideshow than the common one.

Angulo and colleagues concluded that people do value rare species more than common ones and propose that conservationists should be prudent when using rarity to promote conservation. "This is a crucial measure for the conservation of countless plant and animal species, which fall victim to a growing international trade of fuel collections, exotic pet, traditional medicine or luxury markets," explain the researchers.

More information: Courchamp F, Angulo E, Rivalan P, Hall RJ, Signoret L, et al. (2006) Rarity Value and Species Extinction: The Anthropogenic Allee Effect. PLoS Biol 4(12): e415 doi:10.1371/journal.pbio.0040415

Source: Public Library of Science (news : web)