I often see groups of house sparrows foraging in my Oxfordshire garden. There is a privet hedge that in the past was cut back severely, and they like to perch on top of this. Through binoculars I can see that they are pecking at the tops of lopped-off branches, i.e. apparently at bare wood. I have guessed that there must be tiny bugs living in the wood that they're digging out. However, this morning I saw seven sparrows, both male and female, gathered around the low patio wall and pecking eagerly at the mortar in the joints. They were concentrating on one particular joint but also attacked a couple of others. After watching for about five minutes I went outside to take a look, scattering them, and couldn't see anything remotely edible in the wall (and they were still pecking when I scared them off). Any ideas - do they need something from the wood, and calcium or sand from the mortar? Are they able to see microscopic bugs or plants that I can't detect? The garden has berries, seeds in a feeder, dead foliage for overwintering insects, and plenty of accessible water, so the birds don't need to work very hard for sustenance.
Thanks for any answers, and happy new year to all at AAB!

Hi Helen,

I don't know the answer to this, but the explanation for similar observations given at this RSPB site certainly sounds plausible to me. Assuming this is correct then they may be after grit for their gizzards to help with grinding up edible food items.

http://www.rspb.org.uk/advice/expert/pr … cking.aspx