Victoria, who arrived at the Highland Wildlife Park near Aviemore in March this year, turned 19, while Arktos was eight and Walker turned seven.
The two male bears were gifted a huge play ball, splashing about in their enclosure’s pond.
Keepers at the park said the pair have become “best buddies” since they moved in together two years ago, describing their relationship as a “bear bromance”.
Victoria was treated to a special frozen birthday cake made from ice and fish.
Vicky Larkin, head carnivore keeper, said: “Although they often are given a range of polar bear-friendly toys, this is the first time we’ve given Walker and Arktos, our very playful male polar bears, a huge ball specially made for large powerful animals and we were extremely excited to see their reaction.”