Now that it's winter, I seem to have a problem with mice in the duck's food. Or maybe the problem was there all along, but now I am noticing it. I keep the duck food in a sealed metal trashcan, but have the food in a hanging feeder in their pen. And the mice seem to really enjoy it, as I've seen droppings in the feeder the past few mornings. So I decided to put out some poison for the mice, well away from the duck pen, but in a place I've seen the mice occasionally. I put out these bright green candy-bar looking mice poison bars, and what do I find this morning?.....bright green droppings in the hanging duck feeders! Who knows if the ducks had eaten the "poison dropppings" that were in with their feed! AAAAAARGH! Now I"ll have to watch them closely to see if they get sick. Long story to get to my question, but here goes: Do you think those plug in rodent repellant boxes that emit a high frequency noise would also bother the ducks? Or do birds and rodents not hear the same sounds? Any ideas would be welcome!