Polar bears

SAVE US: There are 25,000 polar bears worldwide. The species is listed as threatened under the US Endangered Species Act because their sea ice habitat is melting. Pictures: Reuters

PLAYTIME: Vitus, an 18-year-old male polar bear, plays with a ball at the Budapest Zoo.

OH CANADA: A three-month-old unnamed polar bear cub that a police officer rescued from native hunters near Fort Severn, Ontario, plays in an enclosure at his temporary home at the Metro Zoo in Toronto.

WHOOPS: A polar bear cub joyfully falls in the snow as his 10-year-old mother passes by in the Moscow zoo.

THREE'S COMPANY: Polar bear cubs play on their first day out on public display at the Ouwehands Zoo in Rhenen, the Netherlands.

ROUGH AND TUMBLE: Two polar bears play in the snow at Moscow's zoo.

OOH THAT'S ICE: A polar bear licks ice cubes in its enclosure during a hot summer day in Munich's zoo.

BREAK IT DOWN: Tatqiq, a three-year-old polar bear cools off by rolling in an icy treat at the San Diego Zoo's Polar Bear Plunge.

LET IT SNOW: Kalluk, a four-year-old male polar bear tackles, tosses and cuddles a snowman in his chilled pool at the San Diego Zoo.

I BELIEVE I CAN FLY: A seven-month-old polar bear cub jumps into the water in the zoo in St Petersburg.

SCRATCH MY BACK: Tania, a 16 year-old polar bear, rests on a snow-capped rock at the Artis zoo in Amsterdam.

STICK WITH ME: Polar bear Commander Sedov swims in his favourite pool after maintenance work in a zoo in the Siberian city of Krasnoyarsk.

COMFIER THAN IT LOOKS: A polar bear nestles into a hole it dug in the 15 tonnes of snow covering the Polar Bear Plunge habitat at the San Diego Zoo.

JUST CHILLING: Polar bear Knut enjoys the cold weather in his enclosure at the Berlin Zoo.

UBER CUTE: Berlin zoo employee Thomas Doerflein plays with polar bear cub Knut during the bear's first presentation in Berlin zoo, in this March 23, 2007 file picture.

INTO THE BLUE: A polar bear swims in a pool in the Wuppertal Zoo.

FETCH: A four-month-old polar bear cub plays in a pool in the zoo in the Siberian city of Krasnoyarsk.

TICKLE ME:Berlin zoo employee Thomas Doerflein plays with polar bear cub Knut.

BIG BALL OF FLUFF: Polar bear cub Knut plays in the Berlin zoo.

HEY THERE: Polar bear cub Knut is pictured during its first presentation in Berlin zoo, March 23, 2007.

TWIST AND SHOUT: Five-year-old polar bear Sedov plays at the Krasnoyarsk Zoo.

AND STRETCH: A polar bear rests in the shade at Vienna's Schoenbrunn Zoo.

SNOOZING: Five-week old cub Vera.

THAT'S MY BABY: Polar bear cub Wilbaer stands next to his mother Coprinna in their enclosure at the Wilhelma zoo in Stuttgart.

MILKING IT: Baby bear Vera.

MINE: Polar bear cub Flocke (Snowflake) at the zoo in Nuremberg.

WHAT'S THIS, THEN? Twin seven-month-old polar bear cubs Nanuq and Arktos play with a fish at Schoenbrunn Zoo in Vienna.

SHAKE IT: A polar bear drys off.

WE ARE FAMILY: One of the newborn polar bear cubs drinks milk from its mother Huggies on their first day out at the Ouwehands Zoo in Rhenen, Netherlands.

LOOK AT ME, MUM! Polar bear cub Wilbaer swims with his mother Corinna in their enclosure at the Wilhelma zoo in Stuttgart.