A major survey of the benefits for bird populations on organic farms has proved a mixed bag for supporters of chemical free agriculture: some species thrive but “it does not hold all the answers” for others.

The survey was carried out for the British Trust for Ornithology and is published in today’s issue of the Royal Society journal, Biology Letters. It concludes:

“The results show that, whilst the total abundance of most farmland birds was higher on the organic farms during these winters, for birds that feed largely on cereal grain and are partly reliant on winter stubbles, this was not the case. It is these species, birds like the yellowhammer, corn bunting and skylark, that are experiencing the biggest declines.”

Report lead author Dr Dan Chamberlain commented, “Organic farming has clear benefits for a range of species but some aspects of organic farming may not currently provide significant benefits to bird species that are limited by winter seed availability.

“Once harvesting is completed, it is general practice for farmers on organic farms to plough in the stubbles to prevent an over-winter weed burden, making this resource unavailable to birds”

• Another scientific survey made public today blames the dramatic decline in bee populations on pesticides used in large scale arable farming – and in the treatment of pot plants for gardeners. Joint research by the insect charity Bug Life and the Soil Association blames a group of “systemic” pesticides called neonicotinoids, widely used to spray crops like oilseed rape and in the production of pot plants.