The Scare-Eyes ball seems to work on birds and, from what I’ve seen, cows. I use it for beans, a favorite bird target. A lot of scientific-sounding info comes with each ball. The shapes and mylar circles are supposed to look like predatory birds to other birds. They come in three colors, which you’re supposed to rotate every three weeks, with six balls minimum to an acre. There’s been only the one yellow one for the last couple of years, but this year, I got three more: yellow, black and white… Better safe than picked to pieces by BIRDS!