About a week ago I started getting emails and calls at the store about people finding dead common redpolls and pine siskins. I called the Wildlife Rehabilitation Center in Minnesota and they had gotten about ten phone calls regarding the same thing. A few days ago, I got a call from Carrol Henderson from the Minnesota DNR saying his office was getting several phone calls from around the mid and northern part of the state regarding sick and dying northern finches. Carrol said that he was getting calls mostly about redpolls and siskins but one yard did have one dead evening grosbeak. He also said that they had eight dead redpolls to examine to try and determine the cause of death. Preliminary results show that the infection that killed the birds was probably viral rather than fungal--so what does this mean?
Viral vs Fungal
The usual culprit when dead birds show up at the feeder is that the feeders are dirty and have mould built upside that is killing the birds. When this happens it's best to take down your feeders and clean them thoroughly with bleach and water or antibacterial soap. If you are unable to completely clean the feeder due to its construction, throw it out and buy a feeder that you can clean. Since the preliminary results lean towards viral that means that the redpolls and finches are passing a virus to each other rather than getting sick from eating directly out of the feeder.
Should you take your feeders down?
If the birds are spreading it to each other, chances are large congregations of birds at a feeder could be infecting each other. By the same token the birds are spreading it to each other by the very nature of the way they behave in flocks whether they are at a bird feeder or not. Some argue that the birds will spread it to each other regardless of your feeder so why not provide meals even for those that will succumb to the infection soon. Others argue that having birds concentrate in your yard could risk spreading it to other species (although the infection seems to only be infecting redpolls and siskins at this point). The bottom line is that it's a personal choice.
We don't know all the facts yet, but we should have more answers Monday or Tuesday.