The story of Hawaii's "invisible" cows

A sign near the Mauna Kea volcano in Hawaii warns visitors of "invisible" cows— dark-colored cows who are hard to spot in foggy or dark conditions. It's become an iconic landmark, and a Mauna Kea gift shop sells invisible cow stickers (available online for $4 plus shipping).

Most of the Mauna Kea access road below Hale Pohaku is open range, and the cows frequently cross the road. Dark colored cows are often invisible in darkness and/or fog. Use extreme caution and drive very slowly in this open range. 

Mauna Kea sign

The sign, at the site of a dormant volcano in a high-altitude region of a Pacific island, may sound like a joke. But there's probably some truth in the warning.

Cattle certainly aren't native to Hawaii— they were domesticated from the auroch and were common in Eurasia. So how did they end up roaming this island in the Pacific?

In the 1790s, a British officer gave the King of Hawaii a few cattle as a gift. The king, eager to increase the population size of a valuable animal, released them into the wild. He imposed the death penalty on anyone who killed the cattle, resulting in unchecked population growth. As the animals reproduced, they and wreaked ecological havoc. Eventually, in the 1830s, the Kingdom of Hawaii began to combat the invasive species.

King Kamehameha III invited cowboys from what is now the American Southwest to train crews of Hawaiian cowboys, called paniolos. They worked to control and domesticate the cows, but the paniolos didn't fix the problem immediately. By one estimate, the cattle population was still near 35,000 in 1848, and even as recently as 2013, Hawaii's DNR has devoted resources to controlling feral cattle.

If you'd like to practice finding invisible cows from the comfort of your home, check out The game is quite simple: you hover your mouse over the screen until you reach a spot where a voice desperately screams "COW!" and you click. Tada, you found the invisible cow!