The two males, called Arktos and Walker, were treated to special treat made from their favourite fish and vegetables.
And the playful bears even got some special enrichment to celebrate the day at the RZSS Highland Wildlife Park near Kingussie, Speyside.
The animals have formed a close bond since Arktos’ arrival from Hannover Zoo in Germany in 2012.
Arktos celebrated his ninth birthday yesterday while Walker will turn eight on December 7.
Their birthday treats were also surrounded by Scotland flags to mark St Andrew’s Day.
Vickie Larkin, head carnivore keeper at RZSS Highland Wildlife Park, said: “It’s fitting that Scotland’s only polar bears should celebrate their birthday in the Highlands on St Andrew’s Day.
“Each year we treat our bears to some tasty enrichment to coincide with their birthdays, helping encourage the bears’ natural behaviours and providing a fun and educational spectacle for our visitors.”
Polar bears are the largest living carnivores and will mostly eat seals in the wild, although they will also hunt beluga whales and seabirds.
They are currently on the International Union for Conservation of Nature’s Red List as a vulnerable species.