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How can I stop sparrows picking the grit off my shed's felt roof?

Sent in by Christine Fazackerley

Since birds don’t have teeth, grit can have an important role in helping them digest their food. The grit is swallowed and remains in the part of the digestive system called the gizzard.

The food and grit are ground together by the muscles in the gizzard, resulting in the food being broken into smaller pieces. Whether a bird needs grit is determined by its diet.

The harder the food that a bird consumes, the more grit it needs. Seed-eating birds need more grit than those that feed on insects or fruit, and species that have a variable diet will change their grit intake accordingly.

House sparrows are predominantly seedeaters but during the breeding season, they will feed on insects and provide them for their young. As the summer progresses, natural seeds will become more available to them so their diet will change back to seeds and they will need to take in more grit, perhaps explaining why this behaviour has started in your garden.

Putting out an alternative source of grit could help with this problem. It's worth providing a container of grit of the same size as the grit on your roof, near to a feeding area where will see it and hopefully, they will take this easy source of grit rather than continuing to take it from the roof.

It's important not to put out 'grit' used for de-icing roads, as salt can poison birds. Grit suitable for birds is available from pet shops.

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