The world’s most endangered tigers have started a family in Greece, offering hope for a predator rapidly vanishing from the wild. Three two-month-old Sumatran tiger cubs received identification microchips and their first vaccinations on Tuesday at a zoo near Athens, as part of a global effort to build a backup population. The Sumatran tiger, classified as critically endangered, is found only on the Indonesian island of Sumatra, which is slightly larger than Sweden. As few as 400 are believed to...