Several bird species die after being infected with WNV and can therefore serve as another early warning system for detection of the virus.  The California Department of Public Health coordinates a statewide surveillance of dead birds.  They can be reported online. The CDPH will respond accordingly. The bird has to be intact and dead less than 24 hours in order to be tested. If birds are not picked up by the end of the day you can double-bag them and safely dispose of them in the garbage.