Editing Giant panda (section)

===Reproduction===
[[File:Chengdu-pandas-d18.jpg|thumb|A giant panda cub]]
Giant pandas reach sexual maturity between the ages of four and eight, and may be reproductive until age 20.<ref>{{cite web |title=Giant Panda Reproduction |work=National Zoological Park| url=http://newsdesk.si.edu/kits/pandas/nzp_panda_reproduction.pdf |access-date=13 April 2008 |archive-url=https://web.archive.org/web/20080527204441/http://newsdesk.si.edu/kits/pandas/nzp_panda_reproduction.pdf |archive-date=27 May 2008}}</ref> The mating season is between March and May, when a female goes into [[estrus]], which lasts for two or three days and only occurs once a year.<ref name=reproduction>{{cite web |url=http://www.4panda.com/panda/pandatips/reproduction.htm |title=Giant Panda Reproduction |access-date=14 April 2008 |last=Kleiman |first=Devra G |archive-url=https://web.archive.org/web/20080807161537/http://www.4panda.com/panda/pandatips/reproduction.htm |archive-date=7 August 2008}}</ref> When mating, the female is in a crouching, head-down position as the male mounts her from behind. [[copulation (zoology)|Copulation]] time ranges from 30 seconds to five minutes, but the male may mount her repeatedly to ensure successful fertilisation. The [[gestation]] period is somewhere between 95 and 160 days - the variability is due to the fact that the fertilized egg may linger in the reproductive system for a while before implanting on the uterine wall.<ref name=reproduction/> Giant pandas give birth to twins in about half of pregnancies.<ref name=Ruane23Aug>{{cite news |url=https://www.washingtonpost.com/local/giant-panda-preparing-to-give-birth-national-zoo-says/2015/08/22/bba0fd2c-4804-11e5-8ab4-c73967a143d3_story.html |title=National Zoo's giant panda Mei Xiang gives birth to two cubs hours apart |first1=Michael E. |last1=Ruane |first2=Elizabeth |last2=Koh |first3=Martin |last3=Weil |newspaper=The Washington Post |date=23 August 2015 |access-date=24 August 2015 |archive-date=24 August 2015 |archive-url=https://web.archive.org/web/20150824004041/http://www.washingtonpost.com/local/giant-panda-preparing-to-give-birth-national-zoo-says/2015/08/22/bba0fd2c-4804-11e5-8ab4-c73967a143d3_story.html |url-status=live }}</ref> If twins are born, usually only one survives in the wild. The mother will select the stronger of the cubs, and the weaker cub will die due to starvation. The mother is thought to be unable to produce enough milk for two cubs since she does not store fat.<ref name="Panda Facts">{{cite web |url=http://www.pandasinternational.org/wptemp/education-2/panda-facts/|title=Panda Facts|publisher=Pandas International|access-date=26 August 2015|archive-url=https://web.archive.org/web/20150924063658/http://www.pandasinternational.org/wptemp/education-2/panda-facts/ |archive-date=24 September 2015}}</ref> The father has no part in helping raise the cub.<ref name="Dudley 9" />

When the cub is first born, it is pink, blind, and toothless,<ref name="Dudley 9" /> weighing only {{cvt|90|to|130|g}}, or about {{sfrac|1|800}} of the mother's weight,<ref name="Encyclopædia Britannica Online"/> proportionally the smallest baby of any placental mammal.<ref>''Guinness World Records 2013'', Page 050, hardcover edition. {{ISBN|978-1-904994-87-9}}</ref> It nurses from its mother's breast six to 14 times a day for up to 30 minutes at a time. For three to four hours, the mother may leave the den to feed, which leaves the cub defenseless. One to two weeks after birth, the cub's skin turns grey where its hair will eventually become black. Slight pink colour may appear on the cub's fur, as a result of a [[chemical reaction]] between the fur and its mother's [[saliva]]. A month after birth, the colour pattern of the cub's fur is fully developed. Its fur is very soft and coarsens with age. The cub begins to crawl at 75 to 80 days;<ref name="Encyclopædia Britannica Online"/> mothers play with their cubs by rolling and wrestling with them. The cubs can eat small quantities of bamboo after six months, though mother's milk remains the primary food source for most of the first year. Giant panda cubs weigh {{cvt|45|kg}} at one year and live with their mothers until they are 18 months to two years old. The interval between births in the wild is generally two years.<ref name="Sept Exam">{{cite web |url=http://animal.discovery.com/videos/panda-update-september-cub-exam.html|title=Panda Update: September Cub Exam |date=4 May 2006 |publisher=Discovery Communications, LLC|access-date=9 August 2010|archive-date=7 November 2010|archive-url=https://web.archive.org/web/20101107220300/http://animal.discovery.com/videos/panda-update-september-cub-exam.html|url-status=live}}</ref>

Initially, the primary method of breeding giant pandas in captivity was by [[artificial insemination]], as they seemed to lose their interest in [[mating]] once they were captured.<ref>{{cite news |title=National Zoo's Giant Panda Undergoes Artificial Insemination |url=http://www.nbc4.com/news/15643501/detail.html |work=[[NBC]] |agency=Associated Press |date=19 March 2008 |access-date=13 April 2008 }}{{Dead link|date=December 2019 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> This led some scientists to trying methods such as showing them [[Panda pornography|videos of giant pandas mating]]<ref>{{cite news |first=Narunart |last=Prapanya |title='Panda porn' to encourage mating |url=http://edition.cnn.com/2006/WORLD/asiapcf/01/25/panda.passion/index.html |publisher=[[Time Warner]] |date=25 January 2006 |access-date=13 April 2008 |archive-date=5 April 2008 |archive-url=https://web.archive.org/web/20080405191046/http://edition.cnn.com/2006/WORLD/asiapcf/01/25/panda.passion/index.html |url-status=live}}</ref> and giving the males [[sildenafil]] (commonly known as Viagra).<ref>{{cite news |title=Pandas unexcited by Viagra |url=http://news.bbc.co.uk/2/hi/asia-pacific/2246588.stm |work=BBC News |date=9 September 2002 |access-date=13 April 2008 |archive-date=5 October 2007 |archive-url=https://web.archive.org/web/20071005065008/http://news.bbc.co.uk/2/hi/asia-pacific/2246588.stm |url-status=live}}</ref> In the 2000s, researchers started having success with captive breeding programs, and they have now determined giant pandas have comparable breeding to some populations of the [[American black bear]], a thriving bear species.<ref name="pandasinc">{{cite magazine |first=Lynne |last=W. |title=Pandas, Inc. |url=https://www.nationalgeographic.com/magazine/?fs=animals-panther.nationalgeographic.com |url-status=live |archive-url=https://web.archive.org/web/20150903225830/http://ngm.nationalgeographic.com/2006/07/panda/warren-text?fs=animals-panther.nationalgeographic.com |archive-date=3 September 2015 |magazine=[[National Geographic Magazine]] |date=July 2006 |access-date=10 April 2008 }}</ref><ref name="WWF"/>

In July 2009, Chinese scientists confirmed the birth of the first cub to be successfully conceived through artificial insemination using frozen sperm.<ref name="Baby panda born from frozen sperm"/> The technique for freezing the sperm in [[liquid nitrogen]] was first developed in 1980 and the first birth was hailed as a solution to the dwindling availability of giant panda semen, which had led to inbreeding.<ref name="First panda cub born using frozen sperm">{{cite news |title=First panda cub born using frozen sperm|date=25 July 2009 |url=http://www.irishtimes.com/newspaper/world/2009/0725/1224251307368.html |access-date=26 July 2009|newspaper=The Irish Times |archive-date=16 October 2011|archive-url=https://web.archive.org/web/20111016052058/http://www.irishtimes.com/newspaper/world/2009/0725/1224251307368.html |url-status=live}}</ref><ref name="China announces first panda from frozen sperm"/> Panda semen, which can be frozen for decades, could be shared between different zoos to save the species.<ref name="Baby panda born from frozen sperm">{{cite news |url=http://news.bbc.co.uk/2/hi/asia-pacific/8168491.stm |title=Baby panda born from frozen sperm|date=25 July 2009|access-date=26 July 2009|publisher=BBC|archive-date=26 July 2009|archive-url=https://web.archive.org/web/20090726144209/http://news.bbc.co.uk/2/hi/asia-pacific/8168491.stm|url-status=live}}</ref><ref name="World's 1st giant panda born from frozen sperm in SW China">{{cite web|url=http://news.xinhuanet.com/english/2009-07/24/content_11766726.htm |title=World's 1st giant panda born from frozen sperm in SW China|date=24 July 2009|access-date=26 July 2009|publisher=Xinhua News Agency|archive-url=https://web.archive.org/web/20091226013440/http://news.xinhuanet.com/english/2009-07/24/content_11766726.htm|archive-date=26 December 2009}}</ref> As of 2009, it is expected that zoos in destinations such as San Diego in the United States and [[Mexico City]] will be able to provide their own semen to inseminate more giant pandas.<ref name="China announces first panda from frozen sperm">{{cite news |url=https://www.usatoday.com/tech/science/2009-07-24-panda_N.htm|title=China announces first panda from frozen sperm|date=24 July 2009 |access-date=24 January 2011|work=USA TODAY|first=Tini|last=Tran|archive-date=23 June 2011|archive-url=https://web.archive.org/web/20110623190258/http://www.usatoday.com/tech/science/2009-07-24-panda_N.htm|url-status=live}}</ref> 

Attempts have also been made to reproduce giant pandas by [[interspecific pregnancy]] where cloned panda embryos were implanted into the uterus of an animal of another species. This has resulted in panda fetuses, but no live births.<ref>{{Cite journal |last1 = Chen |first1 = D. Y. |last2 = Wen |first2 = D. C. |last3 = Zhang | first3 = Y. P. |last4 = Sun |first4 = Q. Y. |last5 = Han |first5 = Z. M. |last6 = Liu |first6 = Z. H. |last7 = Shi |first7 = P. |last8 = Li |first8 = J. S. |last9 = Xiangyu |first9 = J. G. |last10 = Lian |first10 = L. |last11 = Kou |first11 = Z. H. |last12 = Wu |first12 = Y. Q. |last13 = Chen |first13 = Y. C. |last14 = Wang |first14 = P. Y. |last15 = Zhang |first15 = H. M.| year=2002| title=Interspecies implantation and mitochondria fate of panda-rabbit cloned embryos| journal=Biology of Reproduction| volume=67| issue=2| pages=637–642| pmid=12135908| doi=10.1095/biolreprod67.2.637| doi-access=free}}</ref>