Prince Charles has described his “alarming realisation that I have reached the biblical threshold of three score years and 10, with all the scars that go with it” as he celebrates his 70th birthday.

The occasion was marked with the release of an official family photograph, and revelations about a few of the prince’s favourite things.

Talking to turkeys – specifically his rare breed Crollwitzers – is up there, along with pheasant crumble pie, and naming the red squirrels he invites to run around inside his Scottish retreat at Balmoral.

Prince Charles salutes at Cardiff Castle in Wales on 11 June 1969. Photograph: AP

“They come into the house at Birkhall and we get them chasing each other round and round inside. If I sit there quietly, they will do so round me. Sometimes, when I leave my jackets on a chair with nuts in the pockets, I see them with their tails sticking out as they hunt for nuts,” Charles writes in a special birthday edition of Country Life magazine, which he has guest edited.

He is “completely infatuated” by the red squirrels, Prince William tells the magazine, “to the extent that he’s given them names and is allowing them to come into the house!”

Charles’s choice of magazine articles reflects his passion for traditional rural skills and pursuits, including flint-knapping, hedge-laying, cheese-making and forestry, as well as his favourite view – across Royal Deeside to the summit of Lochnagar.

Gail Sprake, 60, chairwoman of the Rare Breeds Survival Trust, confides that Charles enjoys feeding and talking to his Crollwitzer turkeys.

Prince Charles and his wife Camilla. Photograph: Vickie Flores/EPA

Ian Tennant, 63, head gillie at Gordon Castle estate, Morayshire, reveals the prince is “an excellent, traditional fisherman, preferring to use a 1930s greenheart fly rod rather than one made with today’s popular space-age materials”.

Stick dresser, Wilf Laidler, famed for his depiction of animals on walking sticks and shepherds’ crooks, tells of royal commissions including a stick with a ram’s head with curly horns for the Queen, and his’n’hers sticks with brown trout and the Duke of Cornwall’s insignia for Charles and Camilla.

Other princely passions include delphiniums; he has planted a 130ft long border of the flower at Dumfries House, the Palladian mansion in Ayrshire he saved in 2007.

On his favourite pheasant crumble pie recipe, Charles writes: “I got this recipe from someone I know. It’s delicious,” adding: “I invented a grouse one recently, as well as moussaka with grouse (it doesn’t always have to be lamb) – in other words, groussaka”.

A then eight-month-old Prince Charles, held by his mother, the then Princess Elizabeth, and father Philip, at their summer residence in Ascot, England. Photograph: AP

In a long editorial, he warns that the countryside and its people cannot be taken for granted. Unless action is taken, “we may be the last generation fortunate enough to experience the wonderful people, skills and and activities of our countryside, some of which I have tried to highlight in this special edition of Country Life,” he writes.

Prince Charles in the gardens of Clarence House, with the Duchess of Cornwall, the Duke and Duchess of Cambridge, Prince George, Princess Charlotte, Prince Louis, and the Duke and Duchess of Sussex. Photograph: Handout/Clarence House via Getty Images

On Wednesday, Charles will celebrate his landmark age at a birthday banquet hosted by the Queen at Buckingham Palace and attended by family, close friends and European royalty. He is also due to attend a tea party where he will meet 70 other septuagenarians.