ATLANTA -- Here is a reproduction timeline provided by Zoo Atlanta:

March 28-30: Ovulation and Attempted Mating

After hormone levels indicated ovulation was approaching, the pair was put together to allow breeding to take place. Although Yang Yang and Lun Lun both exhibited normal behaviors, attempts at mating were unsuccessful this year. Zoo Atlanta staff believed the behavior observed was encouraging for future mating attempts.

March 29 & 30: Artificial Insemination

After determining that the pair was unlikely to successfully breed this year because of behavioral inexperience, Zoo Atlanta employed artificial insemination. This procedure has resulted in many giant panda pregnancies and has no effect on future natural efforts to reproduce. Fresh semen was collected from Yang Yang for insemination.

March 31 – August 6: Tracking Possible Pregnancy and Preparation for Birth

Zoo Atlanta continued hormone tracking, recording behavior and used ultrasound to detect a possible pregnancy as well as prepared the nursery for potential birth(s).

August 7: Birth Watch

Zoo Atlanta initiated 24-hour watch based on hormonal changes that are consistent with pregnancy and pseudo-pregnancy, a phenomenon in which the behavioral and hormonal signs of pregnancy are exhibited but the female panda is not actually pregnant. Lun Lun continued to show normal activity and received her usual diet (bamboo and high fiber biscuits) until August 12 when her activity level began to decrease. This is normal for both pregnancy and pseudo-pregnancy.