Winter stubbles

Winter stubbles

Seed-eating birds generally experience a glut of food in the autumn immediately after harvest, but increasingly struggle to find food during the ‘hungry gap’ – the period between stubbles being cultivated and new seed sources becoming available in spring.

What

You can provide a vital resource to help your farmland wildlife survive the winter by retaining 10% of the cropped area as stubble until at least mid-February. Stubble fields not only offer cover for wildlife, but also provide a vital source of winter food for seed-eating birds as well as opportunities for broad-leaved arable weeds to thrive.

farmland birds at Seafield3 Dec 2010 Hywel Maggs

Why

Traditional rotations historically produced a mosaic of different crops and ley areas in which wildlife could find food and shelter. In modern crop rotations, where land is usually cultivated immediately after harvest for winter crops like wheat and oilseed rape, similar opportunities for wildlife can be limited. Seed-eating birds generally experience a glut of food in the autumn immediately after harvest, but increasingly struggle to find food during the ‘hungry gap’ – the period between stubbles being cultivated and new seed sources becoming available in spring.

A lack of winter seed food has been identified as a cause of decline for some of the farmland birds that rely on them. Retaining over-winter stubbles on 10% of arable land is the easiest way to feed these seed-eating birds on arable farms where spring crops are still used, and can help to reverse these declines. Spilt grain and the seeds of broad-leaved weeds make a vital contribution to the winter survival of many seed-eating birds including grey partridges, skylarks, tree sparrows, linnets, yellowhammers, reed buntings and corn buntings.

Spring crops following over-winter stubbles can also provide nesting habitat for lapwings and skylarks, and encourages annual plants to feed birds in spring. Over-winter stubbles and spring cropping are also important for brown hares.

Stubbles allow many arable plants to set seed and gives spring-germinating plants the chance to grow alongside spring crops. Beneficial insects can benefit from the increase in arable plants while others over-winter in the retained stubble itself.

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How

Retain 10% of arable land as over-winter stubble and do not crop until the following spring. Birds will make use of spilt grain and broad-leaved weed seeds within stubble that is left to re-generate naturally after harvest. The weed seed available will largely be that produced by weeds that germinated with the preceding crop. Limited herbicide use or conservation headlands in the preceding crop will greatly enhance the stubble’s benefit to seed-eating birds.

The best stubbles for wildlife receive no herbicides, fertiliser or liming materials between harvest and at least mid-February and the preceding crops are not treated with any pre-harvest desiccant.

It is ideal to retain a variety of stubble heights around the farm to benefit the widest range of birds, as different species feed at different heights. Tall stubble provides cover from predators for skylarks and game birds, but many other birds prefer to feed in shorter stubble where they can see approaching predators and move to cover.

Barley stubble generally attracts more birds than wheat stubble, and spring barley stubble is better than winter barley. Stubble of crops such as oilseed rape and linseed may also provide a rich source of seeds, especially if they are weedy. Undersown crops are less useful for seed-eating birds as the grass crop hides seeds on the ground, but they can support insects such as sawflies which are important food for grey partridge chicks.

Even with over-winter stubbles and retaining some biennial seed mixtures unharvested, some birds can still struggle to find food until May. Supplementary feeding of spare grains and oilseeds in cover crops and farmland bird feeding stations significantly enhance the stubble as a source of late winter food.

stubble from spring-sown barley

In practice

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