New analyses of nearly a decade of Breeding Bird Survey data have shown the benefits of environmental stewardship for farmland birds.
The study, published in the Journal of Applied Ecology, assessed the efficacy of environmental stewardship in relation to national farmland bird populations from 2002 to 2010, using BBS data.
Reversing declines in farmland bird numbers is a major policy of conservation groups, including the RSPB, and a range of management options under environmental stewardship schemes are wholly or partially dedicated to this goal.
To date, research has failed to demonstrate the effects of the schemes on widespread declining bird species.
However, the new study showed that agri-environment schemes, especially Entry Level Stewardship (ELS), have had the effect of reducing the rates of decline rather than reversing them.
It found that management options undertaken by farmers in environmental stewardship to enhance winter seed resources for farmland birds have had a significant effect on population trends since 2005.
The study, funded by Natural England, looked at how populations of bird species associated with English farmland had changed on study sites with different amounts of environmental stewardship management options designed to benefit birds.
It found that options to enhance breeding habitat, such as providing field margins and managing hedges, had little effect across species.
But retaining stubble fields and growing wild bird seed crops tended to have more positive effects. Species found to benefit included yellowhammer, linnet, reed bunting and grey partridge.
Although the effects were significant, they were small, indicating reductions in rates of decline nationally rather than population trends turning upwards.
Gavin Siriwardena, head of land-use research at the British Trust for Ornithology and an author on the paper, said: "It is important to know whether agri-environment management works because of the public money spent on it.
"These results prove that the right management in the right places has real effects on populations, and so that agri-environment schemes work as a mechanism for enhancing national bird populations - they are worth it if we care about the environment we live in."
He added: "We cannot get away from the fact that birds are still declining; we need to keep improving the management options available to farmers and encouraging higher uptake.
"The changes DEFRA is making to ELS should definitely help, but it is quite likely that we will need more revisions to cover the late winter 'hungry gap', for example."