This afternoon whilst walking along the cliff top near my home I saw seven Magpies flying from a garden to a nearby Hawthorn tree. On reaching the tree the birds went into a right ole mobbing frenzy, thus by walking through the branches they would dispel the threat, however in this case there did not seem to be any other bird in the tree except these magpies. They were then joined by a Blackbird & three House Sparrows who also joined in the frenzy. After around five minutes the mobbing ceased & all three species of bird resumed to their normal duties. On looking at the ground underneath the tree I saw a Brown Rat feeding on what looked like a discarded chicken carcass. This was obviously the cause of all the commotion.