Sunday was a day of mixed feelings at Pairi Daiza zoo in Brugelette, southern Belgium. While visitors were excited, as always, to meet the zoo's resident giant pandas, the fact that three of the beloved bears were preparing to leave for their ancestral home in China cast a shadow of sadness on all the joy.

Giant panda Tian Bao and panda twins Bao Di and Bao Mei made their final public appearance at Pairi Daiza on Sunday, before starting a monthlong quarantine to facilitate their journey to China on Dec 10.

Brigitte Morel, a retiree from Brussels, said she has been visiting the zoo since Tian Bao "was a little shrimp", referring to his weight of only 171 grams when he was born on June 2, 2016. Tian Bao, the first giant panda cub born in Belgium, is now big and strong, weighing almost 140 kilograms.

Morel, who visited the zoo three times last week with her grandchildren to say goodbye to Tian Bao and the twins, said she hopes that one day she's able to visit China and see the pandas again. "I am sad," she said. "It (visiting China) has been one of my dreams since I was young."

Frederic Thuillier, a frequent Pairi Daiza visitor from Valenciennes in northern France, sported two panda pins on his coat as he came to bid farewell to his furry friends.

"We all knew they would leave one day, but it's still a big day today. That's why everyone is coming," he said. "It's good to know that they are going to join the reproduction program and return to their country."

A huge board erected next to the giant panda yards drew many visitors, who conveyed their best wishes to the trio in writing.

In 2014, China and Belgium embarked on a giant panda conservation and research cooperation with the arrival of Hao Hao and Xing Hui at Pairi Daiza as part of a 15-year loan agreement. Two years later, the panda couple gave birth to Tian Bao. The twins — male Bao Di and female Bao Mei — were born on Aug 8, 2019.

According to the loan agreement, all panda cubs born at the zoo are required to join conservation and breeding programs in China. The cubs' transfer plans had to be put on hold because of the COVID-19 pandemic. Panda parents Hao Hao and Xing Hui will remain at Pairi Daiza for another five years.

Liu Yang, a panda keeper, burst into tears when asked if she would miss Tian Bao and the twins, all of whom she has been taking care of since their birth.

"I told myself earlier to be strong, to be a cool mom, and let them leave with pleasant memories. But it's too hard... and I'm not going to pretend anymore," she said, adding that she had been preparing for this tough goodbye for six months.

The silver lining, Liu said, is that she will accompany the three to China and stay for a week to help them adapt to their new life at a giant panda base in Sichuan province.

Eric Domb, founder and president of Pairi Daiza zoo, described the moment as "both beautiful and painful" as well as "unique", because this is the first time three pandas will journey together to China from a foreign country.

"Their presence will remain here, in every corner, in the murmur of the trees, in the breath of the wind, like a sweet memory that dances in the soul of this place. Forever, they will remain in our hearts," he said in a message flashed on a screen at the zoo on Sunday.

Domb added that Pairi Daiza will do everything to ensure its panda family continues to grow, "so that other little ones are born, as a promise of life and future".

Liu, the keeper, said she has already drawn up a plan for next year's artificial insemination procedure. "I will do my best. Many panda fans are looking forward to this (more cubs)," she said, adding that over the years, she has felt the Belgian people's love for giant pandas deepen.