It has long been recognized that understanding the ecology and evolution of Avian Influenza Viruses (AIVs) is imperative for predicting and ameliorating the sporadic catastrophic human influenza pandemics that have occurred periodically since the late nineteenth century. The aim of this project is to develop a better understanding of factors that govern transmission and maintain the diversity of influenza strains that circulate in wild birds. This new knowledge will help to predict the geographic spread of AIVs and their movement between species. To achieve this goal, we will (i) develop our theory about environmental transmission, which occurs when flu particles remain infectious for long periods of time in contaminated environments, (ii) explore methods for detecting environmental transmission in epidemiological data, (iii) develop predictions of environmental durability of new, previously unobserved AIV subtypes, and (iv) study the effects of host species diversity on AIV coexistence. This work develops new computational methods that will benefit ecology and epidemiology in general and will enhance understanding of the emergence of influenza in humans. Additionally, this research incorporates for the first time key environmental components, providing a means to identify some potentially important and undescribed properties of AIV transmission and maintenance.