Just Ask the Animals: Fishers With GPS Sensors Show Animal Movements

Oct. 16, 2013 — Many animals are adapting to human encroachment of their natural habitats. Carnivores in particular require territories of sufficient size and so are often forced to move between numerous small habitat patches. To date, scientists often use mathematical models to predict these important routes, but fishers fitted with GPS sensors are now showing that their calculations may be missing the mark if they ignore animal behaviour.

Corridors are spaces that receive too little attention and yet are vitally important. How else would we get from the bedroom to the bath or from the couch to the kitchen? Without the hallway in between, we would starve on the sofa, unable to reach our food. In the wild the areas that connect animals' living spaces are known as corridors. It is vital for the conservation of many species that animals can move freely and safely from their hunting grounds to their mating areas, for example. If a new road is built through the middle of an important corridor, it may put an entire population at risk.

In general, calculations predict which routes the animals will use. Working with colleagues from the USA, Martin Wikelski and his doctoral student Scott LaPoint from the Max Planck Institute for Ornithology in Radolfzell and the University of Konstanz have let the animals define their own routes. They fitted fishers (mammals of the marten family) with GPS sensors and then observed their movements over the course of three winters near the city of Albany in the US state of New York. In doing so, they discovered that the fishers selected completely different routes from those predicted by the models.

"I was really astonished at how bad the models were," says Wikelski, who heads the Department of Migration and Immunoecology at Radolfzell. The two mathematical models together managed to correctly predict only 5 out of 23 corridors. The "Least-Cost Path Analysis" model, with only one correct prediction, fared worse than the "Circuit Theory" model, which at least managed five hits.

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