Fear itself can cut wildlife numbers in half: study

In an experiment, Liana Zanette and her research team tested the impact of fear on the population growth rate over multiple generations in free-living wild song sparrows. Photo by Marek C. Allen Fear of predators - not just the number of prey that predators directly kill - can significantly reduce the number of individuals in prey populations, according to a new Western University study. In fact, fear can reduce wildlife populations by 50 per cent in five years or less, according to the findings by Liana Zanette , Michael Clinchy, and PhD candidate Marek Allen from Western's department of biology. Their study was published today in Proceedings of the National Academy of Sciences (PNAS) . Zanette and her team experimentally demonstrated for the first time in any free-living wild animal that the fear predators inspire can itself reduce prey population growth rates. Their findings conclusively establish that focusing solely on the number of prey predators directly kill while failing to additionally consider fear, as conventionally done, risks dramatically underestimating the total impact predators have on prey population size. -These results have critically important implications for conservation, wildlife management and public policy,- said Zanette, a Western biology professor and renowned wildlife ecologist.