Japan's giant pandas mate sparking hopes of summer cubs However, despite opening a tunnel between their enclosures during Tian Tian's 36-hour peak ovulation window, the pair have so far failed to show any chemistry and not yet mated. Other establishments where pandas are failing to get amorous include Taipei Zoo, where their resident Yuan Yuan and Tuan Tuan did not mate last month despite being on heat. However, officials at the zoo took matters into their own hands when they launched an artificial insemination programme in a bid to help the female Yuan Yuan become pregnant. In Japan, officials will be watching closely the animals at Adventure World to determine how successful the recent mating stint might be. If the female panda has managed to conceive, the zoo will be hoping to welcome new cubs in the summer, according to reports. It is not the first time the pair have mated, with Eimi giving birth to one male and one female cub in 2008 as well as a set of twins two years ago. "They make a nice couple," an official at Adventure World told the Yomiuri newspaper. Earlier this year, Ueno Zoo in Tokyo also confirmed that their two giant pandas in its care managed to mate. Officials are observing their condition after Ri Ri mated with the female Shin Shin in an outdoor enclosure, sparking hopes that the zoo will be able to welcome its first panda cubs in 24 years.