EFFECTS OF AGE, SEX, AND ODORS FROM CONSPECIFIC ADULT MALES ON ULTRASONIC VOCALIZATIONS OF INFANT CS1 MICE

Young CS1 mice aged 2, 4, 6, 8 and 10 days were each sequentially expo sed to odours of urine from strange adult infanticidal and non-infanti cidal males and the number of ultrasonic vocalizations monitored. Ther e was a clear age effect, with pups 6-8 days calling the most, for pup s of 2 and 6 days of age there were significant positive correlations between body weight and number of calls but for 10-day-old pups a nega tive correlation was found. Female pups called more than males, partic ularly when exposed to odours but this was not due to body weight. Ove rall, more calls were produced when odours from infanticidal rather th an non-infanticidal males were presented and individual pups altered t heir ultrasonic output as the odours were changed.