If your neighbour is scared, this means that danger is near and acute. One evolutionary solution is to speed reproduction in hope that one of your offspring survives. These results bring new information about the proximate and ultimate explanations of small mammal behavioural responses under predation risk. Fear of being eaten has the power to shape populations and drive evolution. The effect the authors report is large: mothers exposed to scared males had a higher successful insemination rate compared to unexposed control mothers.
Predation involves more than just predators consuming prey. The study shows that voles are able to determine the difference between the smell of a predator, the smell of a non-stressed vole, and the smell of a vole who encountered a predator.
The ability to distinguish between these cues allows voles to make a more nuanced risk assessment of their current environment. The authors argue that voles perceive the odor of a fearful conspecific to be more reliable as an indicator of acute danger than the pure cue of predator presence in the breeding area. This olfactory “eavesdropping” allows voles to make use of the experiences of conspecifics around them. When the risk of death is high, it may be better to invest in offspring. Females changed their reproductive strategy from cautious to risky, towards terminal investment, after encountering the smell of a fearful vole. MORE
Header image: researchers Marko Haapakoski (left) and Thorbjörn Sievert from University of Jyväskylä. Credit: University of Jyväskylä.