Concept:House sparrows are the most common birds found in India.They are usually brown and grey.They have short tails and small, strong beaks.Most sparrows eat seeds or small insects.Sparrows are social birds and they live in flocks (groups).Explanation:A few years back the population of sparrow birds started to decline and they were not seen that commonly.They are known to be sensitive to magnetic radiation.An increasing number of cell phone towers in cities apparently are bringing down their populations.The microwaves (300 MHz to 300 GHz) emitted by cell phone towers and handsets have been found to be responsible for damaging the eggs and embryos of sparrows. Several countries have observed a reduction in bird diversity coinciding with the increase in Cellular Mobile Base stations.Pollution has also greatly affected the sparrow population in urban areas.Thus, cell phone radiation may be one reason why the house sparrow is disappearing.