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Disentangling the Effects of the Hormonal Stress Response and Immune Function in Wild Birds
Abstract
In this dissertation, I investigated the health of wild birds by focusing on various aspects of both the hormonal stress response and its effects on the immune system. The adrenocortical stress response can predict both survival and reproductive success in birds and the strength of this response can be influenced by a variety of factors including urbanization, climate change, and disease. In my first chapter, I investigated concentrations of corticosterone, the main avian glucocorticoid in wild passerine birds breeding in west Texas, an understudied region. I provide the first reports of corticosterone concentrations in feathers for 12 species of wild birds, and the first reports of stress-induced serum corticosterone concentrations for ten of these species. I also performed exploratory data analysis and found no association between body condition and either feather corticosterone or stress-induced corticosterone concentrations. In my second chapter, I focused on avian haemosporidian parasite communities within the understudied region of the Davis Mountains sky islands in west Texas. I found many novel parasites lineages, no relationship between migratory status of birds and infection rate, and that avian host phylogeny was the primary factor in determining parasite prevalence. In my final chapter, I used a captive population of wild-caught house sparrows to investigate the effects of chronic and acute stressors on the immune response. I found that an acute stressor can influence baseline corticosterone levels 24 hours after exposure. I also found that chronic stressors did not downregulate the immune response and resulted in an increase in the adaptive immune response via cell lysis. Overall, these chapters elucidate the importance of avian research in understudied regions as well as the influence of the hormonal stress response on the health of birds.
Subject
corticosteronechronic stress
acute stress
feather corticosterone
avian malaria
west Texas
sky islands
Citation
Martinez, Viridiana (2023). Disentangling the Effects of the Hormonal Stress Response and Immune Function in Wild Birds. Doctoral dissertation, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /200024.