American robin
The American robin is a known reservoir (carrier) for West Nile virus. While crows and jays are often the first noticed deaths in an area with West Nile virus, the American robin is suspected to be a key host, and holds a larger responsibility for the transmission of the virus to humans. This is because, while crows and jays die quickly from the virus, the American robin survives the virus longer, hence spreading it to more mosquitoes, which then transmit the virus to humans and other species.