Neonatal handling of Amazon parrots alters the stress response and immune function

The influence of neonatal handling on behavior and immune function was asse ssed in Orange-winged Amazon parrots (Amazona amazonica). Chicks (n = 11) w ere gently handled daily from 25 days of age until 38 days post-fledging, w hile control chicks (n = 9) were not handled. At 10 days post-fledging (sim ilar to 66 days of age), chicks were given tests to evaluate tameness (e.g. , willingness to perch on an offered finger). They were then restrained for 10 min, either by being held while perching (handled group) or, because th ey would not perch, by being restrained in a towel (nonhandled group). Seru m corticosterone levels were measured and immune status was assessed by: th e delayed-type hypersensitivity (DTH) response to phytohemagglutinin-P (PH- P) injection; the humoral response to a killed Newcastle disease virus (NDV ) challenge; and heterophil:lymphocyte ratio (H:L). Handled chicks were tam er by all measures of tameness. DTH was greater in nonhandled chicks (P les s than or equal to 0.002), as were serum corticosterone levels (Wilcoxon, P less than or equal to 0.05), while NDV antibody titers were possibly reduc ed(P less than or equal to 0.09). H:L ratios did not differ. We conclude th at handling conditioned the birds to be held in a manner that appeared not to be stressful. The greater DTH response of nonhandled chicks suggests tha t either their DTH response was enhanced by the acute stress of being restr ained in a towel, and/or the DTH response of handled chicks was suppressed as a result of the repeated physiologic stress from handling during the neo natal period. In either event, handling produced marked differences in resp onse to types of restraint that would be typically encountered in the husba ndry of Amazons in captivity. (C) 2000 Elsevier Science B.V. All rights res erved.