Effects of manipulated food availability and seasonality on innate immune function in a passerine

1. The innate immune system is essential for survival, yet many immune traits are highly variable between and within individuals. In recent years, attention has shifted to the role of environmental factors in modulating this variation. A key environmental factor is food availability, which plays a major role in shaping life-histories, and may affect resource allocation to immune function through its effect on nutritional state.
2. We developed a technique to permanently increase foraging costs in seed-eating birds, and leveraged this technique to study the effects of food availability on the innate immune system over a three-year period in 230 zebra finches housed in outdoor aviaries. The immune components we studied were haptoglobin, ovotransferrin, nitric oxide, natural antibodies through agglutination, complement-mediated lysis, and killing capacity of Escherichia coli and Candida albicans, covering a broad spectrum of the innate immune system. We explored effects of food availabilit...