Journal Article

Weed seed resources for birds in fields with contrasting conventional and genetically modified herbicide-tolerant crops

Stuart, Rick C, Firbank, Les G, Haughton, Alison J, Wilson, Jeremy D, Dawson, Robert J.G, Gibbons, David W, Clark, Suzanne J, Perry, Joe N, Rothery, Peter, Bohan, David A, Scott, Rod J

2006

Overview

The UK Farm Scale Evaluations (FSEs) have shown that the use of broad spectrum herbicides on genetically modified herbicide-tolerant (GMHT) crops can have dramatic effects on weed seed production compared to management of conventional varieties. Here, we use FSE data and information on bird diets to determine how GMHT cropping might change the food resources available to farmland birds. More than 60 fields of each of four crops, spring- and winter-sown oilseed rape, beet and maize, were split, one half being sown with a conventional variety, the other with a GMHT variety. Seed rain from weeds known to be important in the diets of 17 granivorous farmland bird species was measured under the two treatments. In beet and spring oilseed rape, rain of weed seeds important in the diets of 16 bird species was significantly reduced in GMHT compared to conventional halves; for no species did it increase. In winter oilseed rape, rain of weed seeds important in the diets of 10 species was significantly reduced in GMHT halves; for only one species did it increase significantly. By contrast, in maize, rain of weed seeds important in the diets of seven species was significantly greater in GMHT halves; for no species was it reduced. Treatment effects for the total weed seed energy available to each bird species were very similar to those for seed rain alone. Measuring the effects on individual bird species was outside the scope of this study. Despite this, these results suggest that should beet, spring and winter rape crops in the UK be largely replaced by GMHT varieties and managed as in the FSEs, this would markedly reduce important food resources for farmland birds, many of which declined during the last quarter of the twentieth century. By contrast, GMHT maize would be beneficial to farmland birds.

• Publisher: The Royal Society
• Subject: agricultural land / Animals / Aves / Beets / Beta vulgaris / Biodiversity / Bird Food / Birds / Birds - metabolism / Birds - physiology / Brassica napus / chemical control / Conservation of Natural Resources / Corn / Crop management / Crops / Crops, Agricultural - drug effects / Crops, Agricultural - genetics / Diet / Farmland Birds / Farmlands / Feeding Behavior / Food Chain / Food crops / Genetically Modified Herbicide-Tolerant Crops / herbicide resistance / Herbicides / Herbicides - pharmacology / herbivores / Oilseeds / Plants, Genetically Modified - drug effects / Plants, Genetically Modified - physiology / Population Dynamics / seed predation / seed productivity / seed rain / seeds / Seeds - drug effects / Seeds - growth & development / transgenic plants / weed control / Weed Seeds / weeds / wild birds / Zea mays