LONDON (AP) — Zoo officials have created a private love nest for Britain’s only pair of giant pandas in hope the fertility-challenged animals will mate — and Wednesday may be their last chance for quite a while.

Keepers at Edinburgh Zoo have opened a “love tunnel” between the enclosures of male Yang Guang and female Tian Tian in a bid to encourage mating, and have turned off the “panda cam” that allows people to watch the pandas online.

It is hoped the privacy will encourage the animals.

Giant pandas have difficulty breeding, with females fertile for only two or three days a year.

Zookeepers brought the pair together Tuesday after tests showed Tian Tian had ovulated. The zoo said that despite “encouraging” signs and some wrestling, they had not mated so far.

The 8-year-old animals met twice Wednesday and had come “closer than ever before” to mating, but again failed to do so, a zoo spokeswoman said.

The zoo may try one last time Thursday, if the female panda’s hormones showed signs she would still be receptive to mating.

The animals — whose names mean Sunshine and Sweetie — arrived from China in December.

They have been drawing a steady stream of visitors to the zoo, which has had to allocate time slots to accommodate those hoping to view the pandas.

The pair, who are on loan, were also removed from public view in January when they were treated for colic.

They are the first pandas to live in Britain in nearly two decades.