Biology ETDs

Publication Date



The following research was undertaken to monitor a glucocorticoid corticosterone to determine whether or not a reduction in glucocorticoids occurs during the critical period of imprinting behavior. Two groups of domestic chicks (Schaffer white Leghorns) were incubated, hatched and maintained under brooding conditions prior to imprinting procedures. Chicks were first divided into seven age groups, four hour intervals, beginning at hatching. The critical period of imprinting behavior was established with Group I. Success of imprinting training in this group was tested 24 hours after the training sessions. The second group provided blood samples taken after imprinting training sessions; they were later used for corticosterone analysis. A competitive protein binding assay was used for the analysis. Untrained chicks were controls for both groups. Results indicate that an imprinting critical period exists in this sub-species. Corticosterone levels in trained chicks were maximum (50-80 ngm/ml) in the 0-4 hr. old groups and declined to a minimum (4-8 ngm/ml) in the 25-28 hr. old group. Corticosterone levels in untrained chicks were minimum (approximately 10 ngm/ml) in the 0-4 hr. old group and increased to a maximum (approximately 55-125 ngm/ml) inthe 21-24 and 25-28 hr. old groups. These results imply that corticosterone levels in trained chicks appear to decrease in the beginning of the critical period with a concomitant increase in approach behavior. These steroid levels in trained animals remain low throughout the critical period. Thus, being exposed to imprinting training seems to be stress reducing. Chicks not participating in imprinting training sessions showed higher corticosterone levels, i.e. higher stress responses.



Document Type


Degree Name


Level of Degree


Department Name

UNM Biology Department

First Committee Member (Chair)

David Landau

Second Committee Member

John P. Gluck

Third Committee Member

Jack L. Omdahl

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Biology Commons