Visitors take pictures of giant panda Xinxin at the panda pavilion in Seac Pai Van Park in south China's Macao, July 5, 2015. Xinxin, one of the giant panda pair Kaikai and Xinxin donated by the Chinese central government as gifts to Macao, celebrated her eighth birthday here Sunday. (Xinhua/Cheong Kam Ka)

Children pose for pictures against the background of giant panda Xinxin at the panda pavilion in Seac Pai Van Park in south China's Macao, July 5, 2015. Xinxin, one of the giant panda pair Kaikai and Xinxin donated by the Chinese central government as gifts to Macao, celebrated her eighth birthday here Sunday. (Xinhua/Cheong Kam Ka)

Giant panda Xinxin eats her birthday cake at the panda pavilion in Seac Pai Van Park in south China's Macao, July 5, 2015. Xinxin, one of the giant panda pair Kaikai and Xinxin donated by the Chinese central government as gifts to Macao, celebrated her eighth birthday here Sunday. (Xinhua/Cheong Kam Ka)

Giant panda Xinxin eats her birthday cake at the panda pavilion in Seac Pai Van Park in south China's Macao, July 5, 2015. Xinxin, one of the giant panda pair Kaikai and Xinxin donated by the Chinese central government as gifts to Macao, celebrated her eighth birthday here Sunday. (Xinhua/Cheong Kam Ka)

Children pose for pictures against the background of giant panda Xinxin at the panda pavilion in Seac Pai Van Park in south China's Macao, July 5, 2015. Xinxin, one of the giant panda pair Kaikai and Xinxin donated by the Chinese central government as gifts to Macao, celebrated her eighth birthday here Sunday. (Xinhua/Cheong Kam Ka)