They've found it a couple of counties over in birds and if I remember correctly in one large farming operation somewhere in the state.  They asked people to stop feeding the birds early if possible or soon as they would be able to find food on their own after winter.  I usually stop for the summer because I want them to eat the bugs!  The last two years though I've had ducks show up, a couple in particular.  So I stopped putting food in the feeder and spread it out in several different areas until the ducks move on.  Shouldn't be to long now and they'll be nesting somewhere else in anticipation of having little ducklings to protect.