Fecal glucocorticoids: A noninvasive method of measuring adrenal activity in wild and captive rodents

To determine the utility of fecal corticosteroid concentration as a measure of chronic stress under laboratory and field conditions, we biochemically and physiologically validated a radioimmunoassay for corticosteroids in thr ee rodent species, house mice (Mus musculus), deer mice (Peromyscus manicul atus), and red-back voles (Clethrionomys gapperi). The biochemical validati ons demonstrated that the assay accurately and precisely measured corticost eroid concentration in the feces. The physiological validation indicated th at the assay was sensitive enough to detect the stress associated with (a) brief handling and bleeding of animals, (b) chronic caloric restriction, (c ) exposure to a novel environment, and (d) exposure to a novel cold environ ment. Our results suggest that fecal measurements reflect stress levels exp erienced by these animals approximately 6-12 h before defecation. Therefore , given a judicious trapping and trap-monitoring protocol, this assay has c onsiderable utility for measuring the stress levels at which animals actual ly exist in the field.