The Amur tiger cubs that were born in Dublin Zoo last year - the first time in over 20 years that the world's biggest cats were born in captivity - made a public appearance over the weekend. After a gestation period of 15 weeks, the two female cubs were born to first-time mother Tundra on October 14. The cubs weighed approximately 1.5 kg (3.3 lb) each then; they have now grown to 15 kg (33 lb) each. Dublin Zoo announced on Instagram: "In case you missed our exciting news, Dublin Zoo is thrilled to announce the birth of two Amur tiger cubs to first-time parents Tundra and Ussuri!" Follow @ieExplained The Zoo authorities have invited suggestions to name the cubs. "To celebrate the birth of the cubs, Dublin Zoo is inviting YOU to suggest a name for the new arrivals based on their Russian origins. Name suggestions can be submitted at and the winners will receive a family day pass to visit Dublin Zoo on a date of their choice," it said. Amur tigers, which were earlier called Siberian tigers, are listed as an endangered species with fewer than 550 of the cats believed to be living in the wild. Amur tigers were once found across the Russian Far East, northern China and the Korean peninsula. In the 1940s, extensive hunting drove the species to the brink of extinction, with no more than 40 tigers remaining in the wild. However, their numbers began to increase after Russia became the first country to grant them protection. At present, Amur Tigers are mostly found in Amur Valley. Amur tigers are the largest and heaviest of all cats with the thickest fur, whose only predators are human beings. In spite of being protected, the cats are killed for their fur and body parts which are used in some traditional medicines and ornaments. Last December, 11 Amur tigers were spotted in the upper reaches of the Dibang Valley in Arunachal Pradesh. A survey by WWF and Global Tiger Forum showed the presence of the species, including two cubs, at the Dibang Wildlife Sanctuary, located in the Dibang Valley District and surrounded by China in the north and east. Also in Express Explained: Crocodylus palustris, a crocodile species that is being removed from the Narmada
