Farmland bird numbers declined dramatically despite the introduction of compulsory set-aside during the 1990s, official figures have revealed.

England’s farmland bird index (pdf) fell by 13% between 1994 and 2007, according to a DEFRA league table charting the fortunes of the country’s bird populations. Over the same period, the all-native bird index fell by just 2%.

The findings appear to call into question the government’s claim that new measures to retain the “environmental benefits” of set-aside would boost bird numbers. But conservationists suggested the decline would be worse were it not for set-aside.

Introduced voluntarily from 1988/89, set-aside became obligatory only after 1992 when producers were forced to take a percentage of land out of production. It was effectively abolished in autumn 2007 when the set-aside rate was set at zero.

Changes in farmland bird populations 1994-2007

Region

% Change

North east

+2

Yorkshire and Humber

+1

North west

-1

East

-13

South west

-14

East Midlands

-17

West Midlands

-18

South east

-27

England

-13

Source: DEFRA

The report reveals a stark north-south divide in bird populations during this period. An increase was recorded in only two regions: the north east and Yorkshire and Humber. But this was more than offset by a 27% decline in the south east.

“These figures seem to reflect the intensification of farming,” said Richard Gregory, RSPB head of species monitoring. “Broadly speaking, the further north you go the less intensive is the farming and the mixture of arable and livestock farming changes.”

Farmland index species include the skylark, grey partridge and yellowhammer. The index declined by 7% between 2006 and 2007, the biggest one-year decline since 1998. But a number of factors were at play, Mr Gregory said.

“There seems to be a clear signal of climate change in these trends. At a European scale, we have witnessed bird population trends correlating with climate projections, so we would expect the effects of climate change in the UK be felt more in the south.”

Despite their best efforts, farmers in the south may also be battling against historical problems, said Mr Gregory. “Often the environment in which they farm has been degraded to such a level that they struggle to make a difference.”

A DEFRA spokeswoman blamed the decline on changes in agricultural practices, such as the decline in mixed farming. “Farmland bird numbers are directly related to the availability of winter and summer food and nesting habitat,” she said.

A government consultation on plans for a set-aside replacement – aimed at encouraging farmers to boost bird numbers by placing land under environmental management – is due to end on 27 May.