Two giant pandas mate in the zoo of Schoenbrunn in Vienna, Austria, March 23, 2016. [Photo/Agencies]

Giant pandas may fake pregnancy for nicer food

Experts say clever pandas display behavior similar to pregnancy to improve their quality of life after they notice the difference in treatment.

The signs of pregnancy include loss of appetite, thickening of the uterus and increased fecal progesterone concentration. Generally speaking, giant pandas thought to be pregnant are moved into single rooms with air conditioning and round-the clock care and also receive more fruit and bamboo. Their trickery is found out when their behavior and physiological indexes return to normal.

Female pandas have a gestation period of just 90-160 days, and their cubs are too tiny to be readily seen via ultrasound. It's also difficult to use hormones as a reliable indicator of panda pregnancy, so sometimes it boils down to having to wait and see. Some pandas have apparently learned to take advantage of a good opportunity and enjoy the finer things while they can.