Sasquatch, the mythical “Bigfoot” of western North America, makes its home deep within the fertile imaginations of gullible people. If you insist on looking for one in the real world, though, you should search in the home of the black bear – at least according to a tongue-in-cheek study of the ape-like creature’s habitat preferences.
The study has a more serious message too: it’s easy to be fooled into believing a plausible-looking habitat analysis, even when the data is totally erroneous.
Conservation biologists often need to predict where rare species are capable of living – for selecting the best site for a national park, for example, or forecasting how badly a species’ range will suffer as the climate changes in the future.
The latest technique for making these predictions is so-called ecological niche modelling, in which researchers log the locations of known species sightings, then gather environmental data for those places to define the ecological limits of the species’ range.
Jeff Lozier, an entomologist at the University of Illinois at Urbana-Champaign, was worried that some people may have been too uncritical in applying the technique. “Whenever you have these new, shiny, easy-to-use approaches, there’s a temptation to use them even before you know what the kinks are,” he says.
So Lozier and his colleagues decided to apply ecological niche modelling to an obviously false data set – Sasquatch sightings. They gathered all reported sightings in the US states of Washington, Oregon and California and used the environmental data to predict Sasquatch distribution.
They found that the model yielded a perfectly plausible prediction about Bigfoot habitats – a warning to modellers that spurious results will not necessarily announce themselves through obvious warning signs.
“The point of the paper is really well taken,” says Dan Warren, an evolutionary ecologist at the University of California at Davis who is an expert in ecological niche models. “I think the literature is rife with people who are over-interpreting what comes out of these models.”
The researchers also compared the niche model for Sasquatch to one they developed for black bear. The two were statistically indistinguishable, they found. This suggests that many supposed Sasquatch sightings may simply be misidentified bears – a mistake that has been made on at least one occasion, Lozier notes.