Fecal corticosterone reflects serum corticosterone in Florida sandhill cranes

Florida sandhill cranes (Grus canadensis pratensis) were conditioned to confinement 6 hr/day for 7 days. On day 8, each bird's jugular vein was catheterized, blood samples were drawn, and each crane was confined for 6 hr. Using a randomized, restricted cross-over design, cranes were injected intravenously with either 0.9% NaCl solution or ACTH (cosyntropin; Cortrosyn; 0.25 mg). During the 6 hr of confinement, fecal samples (feces and urine) were collected from each of five cranes immediately after defecation. Individual fecal samples were collected approximately at hourly intervals and assayed for corticosterone. We showed previously that serum corticosterone did not vary significantly following saline injection, but peaked significantly 60 min after ACTH injection. Maximal fecal corticosterone concentrations (ng/g) were greater (P < 0.10; median 1087 ng/g) following ACTH stimulation compared to maximal fecal corticosterone concentrations at the end of acclimation (day 7; median 176) and following saline treatment (median 541). In cranes under controlled conditions, fecal corticosterone concentration reflects serum corticosterone levels, fecal corticosterone, Grus canadensis pratensis, sandhill cranes, serum corticosterone levels.