Polar bear Walker lured on scales with mackerel
Mackerel fillets in tomato sauce have been used to help staff weigh a polar bear at a Scottish wildlife park.
Three-year-old Walker arrived at the Highland Wildlife Park, near Kincraig, in December 2010 when he weighed about 39 stone (248kg).
Keepers have now weighed him at 63 stone (403kg). He could weigh 80 and 110 stone (500-700kg) once fully grown at five to six years old.
Staff tempted Walker onto the scales with one of his favourite foods.
He is the only polar bear on public display in the UK.
Walker was also one of two polar bear cubs at the centre of a controversy last year over the BBC's Frozen Planet documentary series.
An episode featured the cubs in a den with their mother, with many people assuming they were born and filmed in the Arctic.
But the cubs were actually in a Dutch zoo, as revealed in behind-the-scenes footage on the show's website.
The BBC defended the footage and denied misleading viewers.
Walker had shared an enclosure at the wildlife park with an elderly female polar bear called Mercedes. She had to be put to sleep in April.
The previous year Mercedes was weighed and tipped the scales at 45 stone (291kg).
Una Richardson, the head keeper responsible for Walker, said the male bear had grown considerably since arriving at the park.
She said: "Knowing precisely what he weighs gives us a very good indication of how well he is doing, and should we need to anaesthetise him for any reason, or give him any medication, knowing what he weighs allows us to give him a more accurate and therefore a more effective dose.
"He is a big boy already and is not even a fully-grown polar bear yet."
Ms Richardson added: "We have hopes of getting Walker a mate some time this year, but at the moment he is enjoying his bachelor lifestyle."
In December, plans to pair up Walker with a female mate were delayed because the bear that was selected was thought to have already been pregnant.