Some bird populations are invasive. European starlings aren't from North America but there is estimated over 100 million. Feral pigeons too. So I only see it as

Some bird populations are invasive. European starlings aren't from North America but there is estimated over 100 million. Feral pigeons too. So I only see it as a problem for threatened or endangered species of bird. Also as a tangent, some birds eat cats! Owls, hawks, birds of prey will absolutely snipe cats!