Fecal corticosterone reflects serum corticosterone in Florida sandhill cranes

Florida sandhill cranes (Grus canadensis pratensis) were conditioned to con finement 6 hr/day for 7 days. On day 8, each bird's jugular vein was cathet erized, blood samples were drawn, and each crane was confined for 6 hr. Usi ng a randomized, restricted cross-over design, cranes were injected intrave nously with either 0.9% NaCl solution or ACTH (cosyntropin; Cortrosyn (R); 0.25 mg). During the 6 hr of confinement, fecal samples (feces and urine) w ere collected from each of five cranes immediately after defecation. Indivi dual fecal samples were collected approximately at hourly intervals and ass ayed for corticosterone. We showed previously that serum corticosterone did not vary significantly following saline injection, but peaked significantl y 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 accl imation (day 7; median 176) and following saline treatment (median 541). In cranes under controlled conditions, fecal corticosterone concentration ref lects serum corticosterone levels.