Every year there will be some rather poorly wild birds dying of whatever viruses are around at this time of year, and of course some avian influenza viruses will be among them.
For robust and healthy chickens this usually does not represent a serious danger.
For the last 10 years it was mostly only the factory poultry farming stocks with their overcroweded and stressed out genetically deprived birds that contracted the virus and they even got caught on camera, it being their own vets and personnel (forage and feed master) that carried the virus from one poultry farm to the other by not following the mandatory bio-security protocol and skipping the change of protective clothing and use of the disinfectant mats.