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Why are birds attacking the cement and bricks on a certain part of my garage wall?

Sent in by Sara Ann Shires, Dewsbury

There could be a number of reasons that the birds are pecking at the bricks and mortar of your home.

Firstly, Seed eating birds, such as sparrows and finches, will eat mortar for the grit it contains. Birds have no teeth for crushing food items, so they utilise small, hard pieces of stone, or sand as abrasive digestive helpers. Birds swallow small bits of grit to act like teeth in the gizzard, a specialized stomach constructed of thick, muscular walls used for grinding up food. The grit helps to break down hard foods, such as seeds and the hard exoskeletons of some insects.

Gizzards can also be found in reptiles, earthworms and some fish. Bird gizzards are lined with a tough layer made of the protein keratin, to protect the muscles in the gizzard. All birds have gizzards, but not all will swallow stones or grit.

They could also be a pecking at the mortar to obtain nutrients from it. More common in older houses, limestone is used in cement and mortar and it is largely made up of calcium carbonate. It is a common substance found as rock in all parts of the world, and is the main component of the shells of marine organisms, snails, and eggshells.

Birds need calcium carbonate to form eggshells and captive birds are often offered cuttle bones or broken eggshells to supplement their diet. Wild birds need to find a source themselves and can be seen pecking at mortar on houses and sometimes even taking grit off roads.

To stop them pecking at your house you could try leaving a pile of coarse sand, either on the ground or on a platform feeder, near the problem area. This way they will have an easier option to choose from rather than having to attack your home.

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