Farmland birds are important indicators of agricultural biodiversity because they feed on insects and weeds and need undisturbed nesting areas. Populations of many species have plummeted with the intensification of agriculture.
The government has committed to restoring farmland bird populations to their 1970 level by 2020 as one of its Public Service Agreement targets. The target roughly equates to a doubling in population levels.
The Environmental Stewardship scheme is the government’s key agri-environmental initiative and gives grants to farmers and landowners who restore hedgerows, protect watercourses or adopt practices which benefit conservation.
The ‘entry-level’ scheme, which pays landowners £30 per hectare per year, was launched in March 2005. By December 2006, the Environment Department (DEFRA) had signed nearly 25,000 five-year agreements covering 3.5 million hectares. Another 244,000 hectares are covered by organic and higher-level agreements, bringing the total payments made since the scheme began to £65 million.
But research by Reading University and the British Trust for Ornithology suggests the scheme, in its current form, may not be able to halt the decline in farmland bird populations.
Researchers modelled the response of each species to future landscape changes using a methodology they developed to test the biodiversity effects of new agricultural practices. Similar papers on arable weeds, bumblebees, butterflies and small mammals are to follow.
The bird results, published in Science, suggest the entry-level stewardship scheme will result in marginally lower populations in 2020 than today and only 47% of those in 1970. Without the stewardship scheme, populations would be 42% of their 1970 level by 2020, say the researchers.
"We’re not anti the scheme per se," said Simon Butler of Reading University. "But we’re raising issues related to the level of uptake."
About three-quarters of improvements made by farmers under the entry-level stewardship scheme have been to hedgerows and field margins, he said. "What we’ve seen is that it’s changes in the cropped areas that increase the risk [to farmland birds]."
The programme is particularly ineffective for species, such as the skylark and corn bunting, that rely solely on the cropped area of fields. Farmers should be putting more effort into improving the biodiversity value of these areas, said Dr Butler.
DEFRA says it has commissioned its own review of its agri-environmental programme, due to report in March.
It dismissed Dr Butler’s findings because they omit the higher-level stewardship scheme or predecessors such as the Environmentally Sensitive Areas and Countryside Stewardship schemes, which are now closed to new entrants.
The study also ignored the stewardship scheme’s wider environmental, landscape and heritage targets, said a DEFRA spokesman.
The study arose out of observations made about modern agriculture during DEFRA’s four-year, farm-scale evaluation of herbicide-tolerant oilseed rape and sugar beet. It also included analysis of the effect that widespread cultivation of these crops would have on farmland birds (ENDS Report 375, p 25 ).
Loss of weeds and above-ground invertebrates would affect 39 farmland bird species, it finds, but the overall effect would only represent a slight decrease in 2020 population levels. This is because GM crops would be introduced into a landscape that is already heavily modified, explains Dr Butler.