Individual Variation in Immune Function in the Purple-crowned Fairy-wren (Malurus coronatus)

Immune function is essential for survival. However, individuals vary greatly in their immune function. This thesis examines the possible drivers of variation in immunity and the potential consequences for fitness and survival in wild purple-crowned fairy-wrens. By using a long-studied population, detailed information about life histories can be matched to the immune status of individuals. I focus on variation in baseline immune defences, and how it relates to environmental and intrinsic factors. I assess how this affects the reproductive fitness and survival of these individuals. I find evidence that immune flexibility in individuals could be key to maximising fitness.