Effects of water deprivation on urine marking and aggression in male house mice.

This study assessed the effects of water deprivation on male mouse urine marking and aggressive behaviors and endurance. In Experiment 1, the size of marks and frequency of marking were examined in 3 groups given 3 different weights of potato/day as their source of water. Males receiving the least water, 1.5 g potato/day, marked at significantly lower rates than males receiving 3 g potato/day or 6 g potato/day (p less than 0.01). The size of urine marks of males was judged by a panel to be unaffected by water deprivation. In Experiment 2, water-deprived males were not as aggressive as normal males and when paired with them were almost always subordinated. Experiment 3 tested the hypothesis that water-deprived males lost fights simply because they were weaker than normal males. When water-deprived and normal males were tested to determine the maximum length of time they could swim, no differences were found (p greater than 0.05). We conclude that water deprivation can directly affect the urine marking and aggressive behaviors of male mice. Such changes may be of adaptive importance during times of drought.