Farmers and consumers have been told they can play a crucial role in helping to bring threatened turtle doves back from the brink of extinction.

Operation Turtle Dove, launched at Pensthorpe Nature Reserve near Fakenham today, is a three-year project aiming to reverse an alarming decline in the bird's numbers, which have plummeted by 91pc since 1970.

The farmland bird, revered in literature and folklore as a symbol of love and devotion, has a distinctive 'purring' call which was once a common sound across much of England.

The cause of its population crash is not fully understood, but its diet consists almost entirely of seeds from wild plants which have become scarce in a modern countryside dominated by intensive farming.

The Pensthorpe Conservation Trust is part of partnership including the RSPB, Natural England and sustainable farming specialists Conservation Grade, which is exploring ways to replace lost nesting habitats and food sources.

Captive birds are being studied to see which seed mixtures are the most palatable and nutritious – and the most viable for farmers to plant under agri-environment stewardship schemes.

While working with farmers to re-establish the seed-rich summer feeding grounds vital to the species' survival, the partnership is also urging consumers to buy foods sourced from Conservation Grade farms, which are accredited with a bumblebee logo.

That way, farmers can be rewarded for planting areas of land for the benefit of the turtle dove and other threatened birds.

Simon Tonkin, RSPB farmland bird advisor, said: 'After many years of decline we are facing the very real possibility of losing this beautiful bird from the UK.

'This new project will build on a lot of positive work which has already been done by farmers and conservationists. As well as putting in place measures which will bring back some of wild plants which farmland birds like the turtle dove rely on, we need a better understanding of the causes of this devastating decline.

'My son Robin is three and by the time he is 20 he may no longer be able to see or hear turtle doves purring in the countryside. But all is not lost yet and I am confident we will make a difference for this iconic species.'

Tim Nevard, executive director of Conservation Grade and a Pensthorpe trustee, said the project would study migration routes and seek to understand the birds' feeding patterns in territory strongholds like the Wensum Valley.

He said: 'Probably the most important thing is to bring this knowledge all together in turtle dove-friendly zones, working with stewardship schemes to leverage funds and, most importantly, engaging with consumers so they know how to tell if their food is grown in a way which can directly affect the survival of the turtle dove and other birds.

'They are running out of food in a modern agricultural landscape, but they do not have to. We can tweak the system, but farms still need to be commercially viable and practical. It cannot be at the expense of food production, because the world cannot afford that. But we cannot allow this species to become the next dodo.'

Turtle doves at Pensthorpe are being offered a choice of foods from naturally-occurring weeds, wildflower seeds and cereals to enable the best choices to be made about forage habitat creation.

Chrissie Kelley, head of species management at Pensthorpe, said: 'There are a lot of factors to take into consideration. We are using captive birds here to see what foods are palatable to them, and doing chemical analysis to look at whether that food gives them the nutrients they need.

'Then we talk to the farmers to see what is feasible on a landscape scale. It is a balancing act.'

Among the farmers helping the project are John and Ellie Savory, whose land at Highfield Farm neighbours Pensthorpe and is home to as many as 15 pairs of turtle doves. About 10pc of their 600 acres is used for conservation purposes, with areas of fumitory weeds, red clover and white clover planted in an attempt to boost summer food sources for the birds.

Mrs Savory said: 'All farms have land on their properties which is not commercially viable and it is that 10pc of least productive land which is best placed for environmental schemes. We have put all our most productive land into being productive, and the rest into environmental projects.

'We need to strike that balance to be a sustainable farm. It is really important to us. We are lucky to be in a beautiful part of the world and we want it to stay that way for our children in the future. 'They are lucky because they get to see turtle doves and such a range of wildlife, but if we don't do something now it could be lost. It is such a part of folklore and people just won't be able to relate to it any more. We need to do our bit to make sure it survives.'

Other factors which may be contributing to the decline of the turtle dove, include illegal hunting in the Mediterranean as the species makes its annual migration, agricultural changes in the African wintering grounds and the avian disease trichomoniasis which is common in pigeons and doves.

Mr Tonkin added: 'The story of the turtle dove in Europe is unsettlingly similar to that of the passenger pigeon in North America (now extinct).

'A once common and widespread bird, the passenger pigeon was driven to extinction 100 years ago as a result of hunting and habitat loss. We must not let a tragedy like this happen in our countryside.'

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