THE Singapore Zoo is marking its 40th birthday this year, having welcomed an all-time high of more than 1.7 million visitors in 2012, and wants all 40-year-olds to join in.

From now till December, Singaporeans and Permanent Residents born in 1973 who visit during their birthday month will get a 40 per cent discount on zoo tickets for themselves and four friends.

Those whose birthdays match that of the zoo, June 27, are invited to a party and a special tour on that day.

To pick up an invite, they will have to e-mail the zoo at corpcomms.szg@wrs.com.sg

Activities for children have also been planned for March 16 and 17, during the school holidays.

Said Ms Claire Chiang, chairman of Wildlife Reserves Singapore, which manages the zoo: "Generations of Singaporeans have... visited first as schoolchildren, then as adults with their own families.

"We are honoured to be a part of Singapore life."

The number of visitors has doubled from about 850,000 in 1973.

Most were Singaporeans, not tourists, the zoo said. Last year, they made up two-thirds of visitors.

Ms Chiang said: "We do hope our visitors will continue the tradition of introducing their children, and even grandchildren, to the wonders of wildlife."

Film-maker Ashton Tan, 25, says he visits the zoo every time a new exhibit opens.

"I feel like I can learn something each time I step into the zoo," he said.

The 26ha zoo has more than 2,800 specimens from over 300 species, over a quarter of which are threatened.

A new attraction, the Frozen Tundra exhibit, is expected to open later this month, with polar bear Inuka as the main highlight.