A Western University study recently published in the journal Proceedings of the National Academy of Sciences discovered that fear of predators can reduce wildlife populations by as much as 50% within a five-year period.
Researchers used the sounds of predator or non-predator vocalizations to study the effects on birth and survival rates of free-living wild song sparrows over three annual breeding seasons.
They noted that while adult birds were watching for predators, they weren’t finding food for themselves and their offspring. Other observations include a lower birth rate, fewer birds survived each life stage to adulthood and those that did reach adulthood showed evidence of impaired brain development.
“Having now demonstrated that fear itself can contribute significantly to the total impact predators have on prey populations, we expect this will be found to be true in most ecosystems,” Department of Biology Professor Liana Zanette said. According to the study, “The critical significance of this is that it experimentally establishes that attempting to utilize data on direct killing alone to infer the effects of predators risks dramatically underestimating the total impact predators have on prey populations.”