In winter, the dry polar winds that swept down from Siberia through the northeastern Chinese city of Shenyang used to send excrutiating pains through the arthritic legs of Zhang Fugui. However for her husband, Huang Fuxi, it was the smog from the city's coal-fired power plants that affected his breathing.
So it was small wonder that when a relative invited them to visit the tropical island province of Hainan, they jumped at the chance.
"The pleasant climate and fresh air nailed us, " said Huang, 75, a retired economist who had worked at a state-owned engineering company. "We finally decided to buy our own house not far from my relative's in 2013."
For the past few winters, the couple move down from Shenyang to enjoy square dancing, ping pong and fishing alongside other retirees from the north, staying in a home that cost them just 18,000 renminbi ($3,000). Huang's daily walk is a 35-minute stroll to the seashore.
The burgeoning elderly tourism market hit the headlines in June when a cruise ship on the Yangtze capsized, with hundreds of holidaymakers feared dead. However, well before then tourism experts and real estate developers had noticed a wave of senior travelers who eschew breakneck site-seeing tours in favor of regular migration to second homes in the south.
China's snowbirds mostly come from wealthy northeastern cities, where freezing gales alternate with carcinogenic smog through most of the winter. Traveling for less than the six months required to achieve temporary resident status, seasonal migrants like the Huangs have been dubbed China's "Floating Population."
Developers working in the south have caught on, adding residential units and senior-friendly touches to resorts like wheelchair accessibility and medical monitoring. The annual influx of seasonal migrants to Hainan has even provoked policymakers to ease a rigid internal system linking social services to residency, known as hukou, and reconsider a ban on mortgages to people over 60, the age of retirement for Chinese men -- women can retire as early as 50.
"Elderly people from the northeast have always traveled," said Huang Huang, a researcher at the China Tourism Academy who focuses on the travel habits of older people and is not a relative to the retired couple . "Suddenly, in 2002, they visited Sanya and they found that it's not only a good place for sightseeing but also a very good place to spend the winter. So a few of them started to stay. That was a surprise."
Now over 400,00 elderly people from the northeast migrate to Sanya each winter according the CTA's Huang.
This spring, at the Fourth International Senior Service Expo in Beijing, alongside brochures for adult diapers were pamphlets for luxury complexes in locations including the lush jungles on China's border with Thailand, others in the southern province of Guanxi and many more from Hainan. In pictures, silver-haired grandparents splash in swimming pools with their grandchildren, set up woodland campsites and pilot golf carts across expanses of iridescent green. Billionaire Wang Jialin's Dalian Wanda Group has opened a resort in the south-western province of Yunnan, where many early buyers have been retirees, according to the China Tourism Academy.
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Retirees have been a rare bright spot as China's property market becomes more volatile, especially in Hainan. For years the target of real-estate speculators, the island's residential market is both oversupplied and over-priced. Scared by President Xi Jinping's anti-corruption campaign, officials have set about selling off conspicuously lavish properties in Sanya at discounted prices, according to Zhang Yuchen, founder of Hainan Dai Bo Real Estate.
"Retirees in their fifties from northern China make up most of buyers there," he said. "The developers and owners are playing all their best cards to appeal to them.
Still, Zhang said, developers could do better to serve older buyers by making sure that complexes are equipped with community clinics, supermarkets and easy access to airports and beaches.
In some ways, the government has been quicker to accommodate Hainan's senior migrants than the private sector.
To support Hainan's hundreds of thousands of seasonal residents the province's social security system has been linked with those of provinces in the north. While there is usually a fee for pension withdrawals outside of one's home province, pensioners can take out money in Hainan at no extra charge once a month, according to the China Tourism Academy's Huang.