Three Sumatran tigers have been born at a zoo in Tennessee. Nashville Zoo officials announced that the two female and one male cubs were born Oct. 20. It’s the first time that Sumatran tigers were born at the zoo. The cubs’ mother, 9-year-old Anne, arrived at the Nashville Zoo from the San Diego Zoo in December. Nashville Zoo veterinary officials performed a routine checkup on the cubs Thursday. The International Union for Conservation of Nature lists the Sumatran tiger as critically endangered with fewer than 600 in existence worldwide. Two Sumatran tigers also were born at the San Diego Zoo’s Safari Park in July.