Other birds stage a comeback if you restore their habitat, but this little bird is too sensitive

Emma Parkin, RSPB

That number has risen to 450 as a result of farmers joining up to the Countryside Stewardship scheme, but it remains threatened.

Now the RSPB and English Nature have drawn up an agreement to prevent its habitat being allocated for housing.

Several local authorities were expected to sign on Monday, with others thought to be willing to do the same soon.

Emma Parkin of the RSPB said: "The cirl bunting likes mixed farmland, with dense hedgerows.

"But if that disappears, they will go and you are unlikely to get them back.

'Massive threat'

"Other birds stage a comeback if you restore their habitat, but this little bird is too sensitive.

"We know there's a village just outside Exeter with only three pairs left. If one or two of them fail to breed, that population is effectively lost.

"Housing is a massive threat.

"But that doesn't mean you must never develop. They are very happy to live next door to houses or busy roads, as long as they have their little bit."

Farmers have been encouraged to lay hedges and grow grassy areas for the bird's favourite food - grasshoppers.