Fear of predators leaves long-lasting changes in wild animals: Study

A new study conducted by researchers of Western University demonstrates that the fear of predator can leave long-lasting traces of fearful behaviour comparing its effect with post-traumatic stress disorder (PTSD).

The study was published in the journal -- 'Scientific Reports'.

The study was led by lead researchers Liana Zanette from Western University along with Scott MacDougall-Shackleton and Michael Clinchy.

For the first time, the researchers experimentally demonstrated the effects predator exposure has on the neural circuitry in wild animals which can persist beyond the period of the immediate 'fight or flight' response and can remain measurable more than a week later.

"These results have important implications for biomedical researchers, mental health clinicians, and ecologists," explained biology professor Zanette.

"Our findings support both the notion that PTSD is not unnatural, and that long-lasting effects of predator-induced fear with likely effects on fecundity and survival are the norm in nature."

Maintaining a powerful memory of a life-threatening predator encounter is clearly evolutionarily beneficial if it helps the individual avoid such events in the future and a growing number of biomedical researchers have begun to propose that PTSD is the cost of inheriting an evolutionarily primitive mechanism that prioritizes survival over the quality of life.

The ecologists are recognising the predators and their effects which affect the prey numbers not just by killing them, but by scaring them as well.

The team of researchers conducted the study on wild-caught, black-capped chickadees at Western's Advanced Facility for Avian Research (AFAR).

For two days, several individual birds were exposed to audio playbacks of the vocalisations of either predators or non-predators and then housed together in flocks outdoors for seven days during which time they were not exposed to any further experimental cues.

After this seven-day test period, enduringly fearful behaviour was quantified by measuring each individual's reaction to hearing a chickadee alarm calls, and long-lasting effects on the neural circuitry of fear were assessed by measuring the levels of a genetic transcription factor in the brain (amygdala and hippocampus).