Responses of infant mice to odors of urine from infanticidal, noninfanticidal, and paternal male mice.

Infant mice responded differently to the odors of urine from isolated-infanticidal, isolated-noninfanticidal, and parental males. More ultrasonic vocalizations were produced in response to urine odors of parental males than to those of isolated-infanticidal males and more to infanticidal than to noninfanticidal males. Infants became agitated in the presence of urine odors of infanticidal males and moved away from the odor source whereas they tended to remain stationary in response to urine odors of parental males. The response to urine odors of noninfanticidal males was intermediate. These data support the hypothesis that infanticidal and parental states have different physiological bases and that this physiological difference results in different chemical composition of urine. The data failed to support the hypothesis that infants will attempt to conceal themselves from infanticidal males by remaining quiet.