Experimental effects of early-life corticosterone on the hypothalamic-pituitary-adrenal axis and pre-migratory behaviour in a wild songbird

Thumbnail Image




Pakkala, Jesse

Journal Title

Journal ISSN

Volume Title


University of Guelph


Although laboratory studies have shown that chronic exposure to elevated glucocorticoids during development has profound effects on animals, we still have a poor understanding of the consequences of early-life stress on wild individuals. In an island population of Savannah sparrows (Passerculus sandwichensis), I examined multiple hypotheses to explain how elevated corticosterone exposure during the nestling period influenced both hypothalamic-pituitary-adrenal (HPA) axis function and the subsequent movement and survival of young after they fledged the nest. Corticosterone-treated nestlings had higher baseline corticosterone levels and lower stress reactivity than untreated individuals, and were more sensitive to inclement weather. Corticosterone-treated individuals also had higher rates of temporary emigration outside of the study site than sham or controls. My results provide support for both the ceiling hypothesis and CORT-activity hypothesis, and highlight the importance of tracking individuals across multiple life stages to understand how early life events carry-over to influence both physiology and behaviour.



Savannah Sparrow, Passerculus sandwichensis, annual cycle, carry-over effects, mark-recapture, robust design, stress