Scotland - He is performing handstands and eating constantly, and she is spraying her home with alluring scents - all the signs point to mating season for Britain's giant pandas.
Experts at Edinburgh Zoo, which acquired the pair from China in December 2011, believe the mating window of just a few days each year will take place in the next three weeks.
Female panda Tian Tian, whose name means Sweetie, failed to mate with Yang Guang (Sunshine) last April, but the zoo has made some changes which it hopes will up their chances this year.
Yang Guang is filling up on bamboo in anticipation of the big event, building up his muscle reserves and performing handstands to mark trees, walls and rocks with his scent.
The higher the scent, the stronger the panda, and the more likely a potential rival would be deterred. And at nine years old, Yang Guang is in peak physical condition.
For her part, Tian Tian has been scent marking around her enclosure to let her beau know that she is ready to mate, and the normally quiet pair have been calling out to each other.
The pandas look on course to mate around the same time as last year, at the end of March or the beginning of April.
The zoo will not know until the second half of August if Tian Tian is pregnant, and then they will only have three weeks before a tiny, blind, bald baby panda is born.
Pandas, whose natural habitat lies in mountainous southwestern China, have a notoriously low reproductive rate and are under pressure from factors such as habitat loss.
China has about 1,600 pandas living in the wild.