I saw the article in December's newsletter. Do you ever worry about the birds eating the poisoned mice? Some people say birds can be poisoned themselves this way. What do you think?

I have had same experiences….my birds do not care for dead mice either, I think they prefer the thrill of the hunt  lol  

But my barn cat on the other hand likes 'em dead or alive  :)  & he has even eaten mice after they took 'just one bite' & bit the dust, the poison in a dead mouse is not enough to do in a larger mammal like a cat or dog I do not believe, but IF they ingest the mouse poison directly & in large enough dosage than, yes, it can kill them too. 

I lost a cat one time after he walked on some granular mouse poison that I did not even know he had gotten into, he licked it off his paws, was sick for 2 days & then had to be put down because the vet said there was nothing he could do to save him  ….now I  never ever use the bait packs, I use the bars only & like Doug says, always put them inside pet proof bait boxes….

PS, this works equally well for rats….. I had the joy of my first encounter with rats on my farm just this last simmer…..ick!!