EXPOSURE TO THE CALLS OF PREDATORS OF MICE ACTIVATES DEFENSIVE-MECHANISMS AND INHIBITS CONSUMMATORY BEHAVIOR IN AN INBRED MOUSE STRAIN

As two-minute exposures to the tape-recorded calls of barn and tawny owls activate endogenous opioid-mediated analgesia mechanisms in laboratory mice, the behavioural effects of the calls of a variety of predator and nonpredator species were ethologically assessed. While no clear effect could be seen on cage-orientated behaviour, the calls of the barn owl and tawny owl produced consistent increases in self-orientated, call-orientated and defensive behaviour indicating that these calls were recognised as belonging to predators. The call of the gull also produced an increase in defense, but, as this could be attributed to an increase in attend only, test animals may react to a change in stimulus properties without the gull call unequivocally representing a potential threat. These results indicate recognition of, and appropriate reaction to, the calls of known night-hunting, airborne primary predators of mice by an inbred laboratory strain.