Visitors celebrate as Yun Chuan and Xin Bao, who are the first pandas from China to arrive in the US in 21 years, were due to debut on Thursday, according to the San Diego Zoo. (ZHANG SHUO / CHINA NEWS SERVICE)

California Governor Gavin Newsom declared "California Panda Day" to celebrate the first public appearance of two new giant pandas at the San Diego Zoo on Thursday.

"This week, California is proud to celebrate another iconic bear as a pair of giant pandas make their public debut at the San Diego Zoo," said the proclamation, which was released on Wednesday.

Newsom, who traveled to China last year to discuss issues including economic development and ways to address climate change, said that the conservation collaboration exemplifies the long-standing history of California and China working together toward common goals.

"We hope that the newly arrived panda 'envoys of friendship' will lead to further exchanges and cooperation between California and China," he said in the statement.

Yun Chuan and Xin Bao, who arrived at the end of June, are the first pandas to enter the United States in over two decades. After several weeks of acclimating to their new surroundings, they made their official debut at the Zoo's Panda Ridge on Thursday.

Panda Ridge has been designed to replicate the pandas' native habitat as closely as possible, offering them a comfortable and engaging space in which to live and thrive. It features lush vegetation, bamboo groves and various items to stimulate the pandas' natural behavior.

Yun Chuan prefers to rest lazily on the climbing frames, while Xin Bao, the smaller of the two, is smart and curious, making the most of her opportunities to explore everything around her.

Together, the two pandas consume up to 18 kilograms of locally grown bamboo each day.

At an exclusive media preview on Wednesday, hundreds of panda enthusiasts got a sneak peek at the pandas. Many expressed their excitement about the return of pandas to the zoo, noting that they are an integral part of San Diego's history.

"We felt really sad, the whole city was sad when the pandas left," said zoo visitor Sheron Natalie. "We waited and waited, and finally they came back. We are so happy."

Jessica Chenoweth was likewise enthusiastic. "They're now coming back. It feels like this is their family's home, and I can't wait to bring my son later to see them firsthand," she said.

Adriana Sanchez, a website operator from Mexico, said she will promote the pandas on her site, which has 13,000 followers who are mothers. "We have a song about pandas, and we all love to sing it in Mexico City," she said.

A visitor identified only as Noreen said that the pandas "represent a real sense of peace. That panda right there is a signal of diplomacy between the United States and China. We hope it's a good beginning to bring them back together."

San Diego Mayor Todd Gloria, who visited China in June to participate in farewell ceremonies for the panda pair before they began their journey to the US, said that Yun Chuan and Xin Bao symbolize the enduring friendship between the two countries.

Since the arrival of the pair, the San Diego Zoo has collaborated with Chinese experts to meet the pandas' dietary needs and preferences. Veterinary teams from both the US and China are closely monitoring various health factors, including weight and appetite, to ensure that the pandas thrive.

Staff members have provided the pandas with a variety of fresh bamboo, along with a local adaptation of a traditional Chinese bun called "panda bread".

Pandas are solitary animals in the wild and are housed separately in zoos, except during the brief breeding season. San Diego Zoo officials hope the pandas will eventually produce cubs, with the first opportunity likely to occur next spring or the following year.