BOS J (2013) Cereal stubbles for farmland birds. LIMOSA 86 (3): 122-131.

Efficient harvesting techniques and declines in cereal stubble area and weed seed abundance have resulted in a serious decline of food resources for seed-eating farmland birds in winter. This paper reviews the literature on the value of cereal stubble to birds in winter. Reduced overwinter survival caused by low food availability is one of the most likely mechanisms behind the decline of many farmland passerine populations. Therefore, measures to enhance winter food resources in agricultural areas have been implemented in agrienvironment schemes. Since these measures involve setting aside productive agricultural land, it is likely that they will be implemented on only a limited area. Hence, there is a potential for significant additional gains if effective measures could be implemented within the productive agricultural land area, without compromising agricultural production. One such measure is postponement of the ploughing of cereal stubbles until spring. If allowed to remain until after winter, stubbles provide a strongly preferred, relatively foodrich winter habitat for a range of (partially) seed-eating species, including Grey Partridge Perdix perdix, Skylark Alauda arvensis and buntings Emberiza spp. Although not yet wellinvestigated, there are also indications that cereal stubbles harbour higher vole densities –the most important prey for some raptor and owl species– than other winter habitats available in farmed landscapes.
      From the perspective of seed-eating farmland birds, the quality of cereal stubbles is determined by vegetation characteristics and weed and seed densities, which can be influenced by management. Some studies suggest that restricting the use of herbicides in cereal crops results in higher seed densities in subsequent stubbles. Other studies suggest that seed densities in barley stubbles are higher than in wheat stubbles, which is consistent with higher bird use of barley stubbles as shown in field studies. Although many questions remain on the role that stubbles can play in reversing negative population trends of farmland birds, there is broad consensus that stubbles have more to offer to birds than most other habitats available in the farmed landscape.
      In the Netherlands, overwintering cereal stubbles have largely disappeared. Instead it is common practice to grow a green manure crop after cereal harvest or to plough stubbles in autumn. These practices contribute to soil fertility and/or suppression of weeds. Whether development of a weed population in stubbles results in increased weed pressure in subsequent crops is currently being tested experimentally. One hypothesis is that development of a weed population in stubbles can be tolerated, because standard (chemical or non-chemical) weed management schemes in crops following the stubbles suffice to suppress any extra weeds that may have been present. If this proves true, farmers can possibly be motivated to postpone the ploughing of some of their cereal stubbles to the following spring.

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