Hi Imitation,

Not sure which birds...I've read a few articles on this and they all mention migratory birds ( like the link I posted )...but they don't specify which ones so I assume any bird that comes into contact with an infected bird can be a carrier...but I assume that not all birds that come into contact will become carriers...
just like mositoes...not all mositoes carry the West Nile virus...but they all have the ability to.

Eg