The Royal Society for the Protection of Birds is calling for more farm subsidies to be diverted to environmental schemes, as new official figures point to a further decline in the population of farmland birds.

Results from DEFRA’s “wild bird population indicator” show that, in 2007, breeding farmland birds were at just 52% of their 1970 level. In the last year alone, there was a 3% drop.

“Most of the decline in the farmland bird index occurred between the mid-1970s and the mid-1990s,” says the government’s report. “But it has fallen over the last three years to its lowest recorded level.”

RSPB agricultural policy officer Gareth Morgan said the fall was “deeply troubling”, especially as English farmers were in their third year of environmental stewardship.

“We know the general intensification of farming has accounted for the majority of the historic decline in farmland birds,” he said. “But with good conservation support now available, this year’s results are dismaying.”

The RSPB says its concerns are heightened by the fact these declines have occurred before the removal of set-aside in 2007/2008.

“Unless compensatory measures can be put in place to cover the void left by the removal of set-aside, farmland birds will continue to slide, putting even more pressure on some populations,” said Mr Morgan.

But the NFU has struck back, describing the use of the farmland bird index to judge the impact of agriculture and the performance of environmental schemes as “simplistic”.

Vice-president Paul Temple said it would take more time for the changes in farm management to impact on improving habitats.

“What is more, it is absurd to believe that the figures quoted by DEFRA can somehow be used to conclude that there is a need to consider putting in place measures to mitigate the loss of set-aside. These declines, if correct, have taken place while set-aside was in place!”

The NFU also questioned the relevance of the farmland bird indicator. “How representative can this be when it only features 19 species, with many species familiar to farmers on their land being omitted and yet increasing?” asked Mr Temple.

“Farmland birds, including the swallow, magpie, collared dove and chaffinch – none of which are included in the farmland bird index – have all increased over the past 30 years.”

He also pointed to increases in the number of predators in recent years, which endangered species such as lapwing, grey partridge, yellowhammer and yellow wagtail, which all nest on or close to the ground.

“It is much too simplistic to lay the blame for decreasing numbers at the door of farmland management,” he said. “This is a multi-faceted issue where other elements, such as climate change, encroaching urbanisation and increased traffic, will all be contributory factors.”