Sir David Attenborough has said he feels "unbelievably lucky" to be turning 90.

The naturalist and TV presenter will celebrate the milestone birthday on May 8.

Asked about how he feels about his 90th, he said: "The truthful answer is that I feel unbelievably lucky.

"I have friends, contemporaries, relatives, people who are my age, who can't walk about. I am unbelievably fortunate."

Sir David, who spent Saturday afternoon opening Woodberry Wetlands nature reserve in London to the public for the first time in almost 200 years, said access to the natural world is a "birthright" and should not be regarded as a luxury.

He said: "It's not a luxury this, you know. If it isn't there it's a great deprivation, and if it is there, it's what human beings deserve.

"We are part of it and if we lose contact with the natural world, you lose contact with a great source of pleasure and delight which is your birthright."

The 11-hectare wetlands in Stoke Newington are based around a working reservoir which has been closed to the public since it was built in 1833.

Sir David said the nature reserve was vital for children "above all".

He said it was important for young people "to see the seasons as they pass, to see not just asphalt and brick and concrete, but reeds and willows.

"To see birds coming up here from Africa, to hear above the hubbub of the traffic, to catch a glimpse of a kingfisher."

The naturalist's birthday will be marked by a special BBC One programme, Attenborough At 90, which sees tributes from everyone from the Duke of Cambridge to the Prime Minister.