Ueno Zoo At Giant Panda we have two cows that will soon be entering their breeding season. During this period, we plan to cohabitate them at the appropriate time for mating. In this case, the exhibit will be closed even on open days.

Target animals Giant Panda

Lily Li Li (male) *Photo above
Born on August 16, 2005 at Garyu Conservation Center
Shin Shin (female) *bottom photo
Born on July 3, 2005, at the Garyong Conservation Center

Reason: To live together for the purpose of mating.

Giant Panda Generally, the breeding season for the "Mere Old Man" comes once a year, from February to May. During this period, a female's chance of pregnancy increases for only a few days. Ueno Zoo In the "Breeding" section, we aim to breed naturally and will cohabit with the females when they are ready for mating. Please note that the exhibit will be closed even on days when the park is open.

Period: Breeding season from early March to around May 2014 *Scheduled for a few days during the optimal breeding season.

Decision of cohabitation and time to cancel the exhibition
When it is determined that the breeding season has entered, we will notify you. The exhibit will be closed all day during the period.

Notification
We will announce whether the exhibit will be open or not on our website and at all entrances and exits of Ueno Zoo.

Current Status
The two animals are free to spend their free time in the outdoor area where they can see each other through the fence, but they do not seem to be bothered by each other.

Progress in the last year
Giant Panda Since mid-February 2013, we have been regularly meeting the two animals over the fence to see how they reacted to each other. On March 13, they became less responsive to each other, so we judged that the breeding season was over and reopened the exhibit on March 15. The exhibit was reopened on March 15.
In June, Sing Sing showed signs of pregnancy, but ultimately did not give birth, and it was determined that the pregnancy was a false pregnancy.


[Reference] General trends regarding reproduction, etc. at Giant Panda

1. sexual maturity
Sexual maturity is 6.5 to 7.5 years for males and 3.5 to 4.5 years for females.

2. Breeding season
Breeding season is generally from February to May. In some cases, estrus occurs in the fall. During the breeding season, there is an increase in activity, smelling, increased body cooling due to bathing, decreased appetite, and love cries. The estrus period lasts about 2 weeks, of which only a few days are available for fertilization.

3. gestation period
After mating, the mother gives birth after a gestation period of 83 to 200 days. The gestation period varies among individuals. This is due to implantation delay*, which means that the time from fertilization to implantation may be one day for some, while for others it may take several weeks. The length of pregnancy varies depending on the time it takes for implantation.

4. changes observed during pregnancy
(1) Change in appetite
Around 30 days prior to delivery, the appetite decreases and the animal begins to leave food behind. Appetite is abolished at the time of delivery.

(2) Behavioral changes
Nest-building behavior is observed from about 15 days before parturition. They become inactive around the time of delivery.

(3) Physical changes
Around 30 days before delivery, teats are observed. Swollen pubic area and udder are observed around the time of delivery.

(4) Hormonal changes
An increase in urinary pregnanediol (a metabolized form of progestin, which is necessary to maintain pregnancy) is observed from 3.7 to 8 weeks before delivery. This value falls during the childbearing period.
(When blood is tested, progesterone (a progestin necessary for pregnancy) levels are elevated.)

5. pregnancy confirmation
Although pregnancy is estimated based on the changes observed during pregnancy, a definitive diagnosis is difficult to make because of the physiological phenomenon known as pseudopregnancy (**).

＜Explanation of Terms
Delayed implantation
A phenomenon in which a fertilized egg does not immediately implant into the endometrium, but floats in the uterus as a blastocyst for a while, and then begins implantation and development. This phenomenon has been observed in bears, weasels, pinnipeds, kangaroos, and other animals found in temperate and cold zones. The gestation period varies depending on the time until implantation.

Pseudopregnancy
Pseudopregnancy is not a disease but a physiological phenomenon. It is known that when ovulation occurs, the process is the same as pregnancy even if fertilization does not occur. After estrus, even if the animal is not pregnant, it will exhibit the same phenomena as pregnancy, such as elevated urinary hormone levels, inactivity, long rest periods, loss of appetite, clear teats, swollen breasts, and nesting behavior. This is called pseudopregnancy. After a number of days pass without delivery, the disease ends when the above changes are no longer observed.

References
The Great Bear Cat: Ex situ Conservation Theory and Practice (book published in China)
Breeding Giant Panda: A 20-year record at Ueno Zoo


Related links
​Giant Panda information site "UENO-PANDA.JP" of Ueno Zoo


Top: Leelee (male)
Bottom: Shin Shin (female)

(February 19, 2014)