This really is most peculiar. Invisible means “unable to be seen” so they must assume the cows are there from the pit patter of the calling cards (because cows will litter no matter what you tell them). This may also be a plot of bovine proportions to persuade motorists to go slower in the Hawai’i Mauna Kea volcanic national park. This would be a low blow below the belt of driving freedom. If the cows are real, we suggest the Department of Land and Natural Resources catches them in daytime and spot marks them white with tippex so motorists can see them at night.