After an 11-year hiatus, Ueno Zoo will attempt to artificially inseminate a giant panda as early as this autumn, according to the zoo in Taito Ward, Tokyo.
No giant panda has successfully grown up in the zoo since the male Yu Yu, born in 1988, and no female panda in the zoo has become pregnant over the last three years. Under a spate of hard luck, the zoo has decided to try artificial insemination again after the last such attempt in 2004, hoping to have a long-awaited cub.
Male Ri Ri, 10, and female Shin Shin, 10, came to the zoo from China in 2011. The following year, they produced a cub - the first born in the zoo in 24 years - but it died after only six days. In spring 2013, Shin Shin appeared to show signs of giving birth but was found not to be pregnant. In the springs of 2014 and 2015, the pandas did not mate.
Pandas usually breed between February and May. During that time, female pandas go into heat for about two weeks but are believed to be fertile for only a couple of days. However, there are exceptions, with pandas sometimes going into heat in autumn. Of the 14 pandas that were born and grew up since 2000 at Adventure World in Wakayama Prefecture, five were conceived in autumn.
Breeding via artificial insemination is mainstream among panda-breeding zoos and labs. Ueno Zoo began considering adopting the method and collected sperm from Ri Ri in May, following a recommendation by researchers at the China conservation centre from which the zoo borrows its pandas. The zoo will attempt to artificially inseminate Shin Shin if she shows no desire to mate in autumn despite showing signs of being in heat. If she does not show signs of being in heat, the zoo will postpone the project until next spring.
Ueno Zoo artificially inseminated the panda Huan Huan with the sperm of Fei Fei between 1985 and 1988, successfully producing three cubs. A male, Chu Chu, died, but Tong Tong, a female, and Yu Yu grew up fine. A total of nine such attempts were made between 1994 and 2004 in vain.
Artificial insemination has to be done during the limited period during which females can become pregnant.