Body weight change as a measure of stress: a practical test
We report on the efficacy of body weight change as a measure of trapping and handling stress in two species of wild small mammal: bank voles (Clethrionomys glareolus) and wood mice (Apodemus sylvaticus). We tested two hypotheses: (1) that weight change after capture and
handling is related to the intensity of the trapping and handling regime, and (2) that weight change after an intensive handling regime is related to an individual's current pattern of energy expenditure. Trapped wood mice that were subjected to intensive handling (intensive stressor) lost
more weight than did animals that were handled minimally (less intensive stressor), but this was not the case for bank voles. Patterns and factors related to body weight change in response to intensive handling also differed between the two species: heavier and non-breeding bank voles were
more likely to lose weight, but this was not true for wood mice, and none of the factors we measured was found to affect weight loss in this species. Our results were broadly consistent with the predictions of the biological cost hypothesis. We discuss the limitations and benefits of weight
loss as a measure of stress.