Other factors which can promote viral emergence include globalisation; in particular, international trade and human travel/migration can result in the introduction of viruses into new areas. Moreover, as densely populated cities promote rapid pathogen transmission, uncontrolled urbanization (i.e. the increased movement and settling of individuals in urban areas) can promote viral emergence. Animal migration can also lead to the emergence of viruses, as was the case for the West Nile virus which was spread by migrating bird populations. Additionally, human practices regarding food production and consumption can also contribute to the risk of viral emergence. In particular, wet markets (i.e. live animal markets) are an ideal environment for virus transfer, due to the high density of people and wild/farmed animals present. Consumption of bush meat is also associated with pathogen emergence.