Date of Award

Spring 5-4-2024

Document Type

Honors Thesis



First Advisor

David Swanson, Ph.D.

Second Advisor

Andrea Liebl, Ph.D.

Third Advisor

Bernie Wone, Ph.D.


oxidative balance system, antioxidants, seasonal flexibility, songbirds, South Dakota

Subject Categories



The oxidative stress system allows air-breathing animals to deal with the potentially harmful byproducts of metabolism. How this system reacts to the increasing thermoregulatory demands in winter for birds from cold winter climates is poorly understood. The purpose of this project was to compare the oxidative balance of summer (warm acclimatized) and winter (cold acclimatized) phenotypes of overwintering songbirds in South Dakota to determine if there is a significant difference between the seasonal phenotypes and among species. Seasonal differences in oxidative balance were expected due to the increased metabolic costs of elevating metabolism to maintain body temperature during winter. Blood samples were taken from four resident songbird species near Vermillion, South Dakota, during the summer and winter of 2023-2024. The overwintering species studied were the American goldfinch (Spinus tristis), black-capped chickadee (Poecile atricapillus), house finch (Haemorhous mexicanus), and house sparrow (Passer domesticus). The red blood cells and plasma from the samples were analyzed for reactive oxygen species production, levels of antioxidant activity, total antioxidant capacity, and oxidative damage. There were two predicted outcomes. The first was that a higher level of oxidative damage would be present in the winter acclimatized birds due to the elevated metabolism. The second was that all antioxidants would be present in higher amounts in the winter to offset the elevated metabolism. The results supported neither of these predictions, with levels of lipid damage being higher in the summer and varying levels of enzymes across seasons and species. These data suggest that the higher thermoregulatory costs in winter do not result in consistently elevated oxidative damage or antioxidant capacities relative to summer in small resident birds in cold climates.

Included in

Biology Commons



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