Saline intake after shifts to water in hamsters and gerbils

In Experiment 1, hamsters and gerbils were given a 24-hr two-bottle test with saline and water for eight days before being placed on a water-only condition for the subsequent four days. On day 13 the saline bottle was returned to the animals and their intake of saline and water was monitored for another six days. Comparisons were made of the animals' intake of saline during the last two pre-withdrawal with that during the first two post-withdrawal days. Saline intake was enhanced in male but not in female gerbils following the 4-day withdrawal period. In contrast, male hamsters showed a decrement in their saline intake while female hamsters showed no significant change in these pre- and post-withdrawal measures. In Experiment 2, a between-groups design was used to test for differences between the saline intake of hamsters and gerbils exposed to the experimental (saline withdrawal) and control (no withdrawal) conditions. When tested with 0.45% or 2.0% saline solution, there was no significant difference between experimental and control hamsters. The results with male gerbils indicated a significant withdrawal effect when the animals were tested with 3.0% saline but not with 4.0% NaCl solution. The implications of these results for a behavioral taxonomy of "compensators" and "noncompensators" are discussed.