For about three months I carried out my master project at the A. P. Leventis Ornithological Research Institute – this project is within the larger PhD research project of Chima Nwaogu that investigates how variation in life history traits and immune function arise from variation in environmental conditions in tropical environments. My work focused mainly on the aviary experiments; using Common bulbuls. Four aviaries housed ten bulbuls each that are fed either invertebrates or fruits. We test the effect of diet on condition, immune function and the gut micro biome. To do this, I monitor how common bulbuls vary body mass throughout the day depending on diet and also collect blood samples and cloacal swabs fortnightly for immune assays and gut microbial analyses respectively.