Good eats are a typical attribute of a good home. But the maxim’s developed a mortal twist for bison. The animals are the subject of a new study that appears on the cover of the January Ecology Letters that challenges the idea that collective behavior is an unequivocal advantage for creatures exhibiting it.

In the bison’s case, following each other to profitable forage led them into an ecological trap. When they went outside the boundaries of a protected national park, attracted by rich forage on agricultural land, they were exposed to hunting. Between 2005 and 2012, the herd suffered 12 percent annual adult mortality from hunting deaths, as they grazed patches of farmland planted with timothy hay and alfafa.

The study was based on data from 49 collared female bison at Prince Albert National Park in Canada, collected by lead author Marie Sigaud of Laval University. Under the direction of Laval Professor Daniel Fortin, who first began studying the bison of PANP in 1996, Sigaud conducted field work to gather information on kill sites, vegetation quality, and foraging behavior.

Santa Fe Institute Omidyar Fellow Andrew Berdahl designed the quantitative model that was used to support the idea that the social transmission of maladaptive behaviour led to the bison’s population decline.

Berdahl and his collaborator John Fryxell developed the quantitative model at SFI over what they describe as a very productive lunch. They based it on a disease model that applies the concept of a susceptible individual being infected with a pathogen from a infected individual, to a naive bison learning about the tasty, yet dangerous, farm land from another bison who had visited it previously.

In a fusion-fission society, the herd frequently separates and regroups into new clusters. Just one animal who has located a tasty patch, and returned to tell the tale, can be the agent of bad information transmission for many.

Most collective behavior studies focus on the benefits, says Berdahl. The novelty of this experiment’s findings, says Fortin, lies in its identifying new pitfalls of collective decision-making—that improving the collective ability to find high-quality forage has led bison to choose a very wrong location for species fitness.


Read the paper in Ecology Letters (November 22, 2016)