Science - January 27, 2011

Birds only go organic in the winter

It is known that intensive agriculture is a disaster for field birds, as they need rich field borders. Flavia Geiger's research confirms this but adds new insights on birds' preferences for organic food sources.

Birds are no particularly bothered whether their food is organically sourced or not. Not in the summer, that is. It is a different story in the winter, when they do prefer to frequent organic farms. These were the findings of Flavia Geiger, who got her PhD last week. Geiger researched the effect of intensification of agriculture on field birds in eight different European countries. One of the things she looked at was the difference between conventional and organic farms. It is well known that intensification is a disaster for birds that brood on farmland, and this comes out very clearly in Geiger's study too. But from a birds' eye view, organic farm management is not a must in the summer. This was a remarkable finding. Organic management and nature management on farmland are the main weapons against the effects of intensification. Geiger did not find more birds on organic farms than on conventional farms, however. She thinks this is explained by the choice of crops on the farms. 'A number of birds have a preference for certain crops... Birds on organic farms are also more often disturbed by mechanical methods of weeding.'
But in the winter the tables are turned and organic farms are more popular with the birds. There are significantly more birds and more different species in organic farms in the winter. This is because there is more food (weeds and their seeds) to be found then.

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