Urban noise could be the key cause of the declining sparrow population in the city.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/noise-pollution-cause-dwindling-sparrow-population-study
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/times-india-jaipur
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/noise-pollution
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/wildlife
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/birds
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/sparrow
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/environment
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/rajasthan
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/andhra-pradesh
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/kerala
[11] http://admin.indiaenvironmentportal.org.in/category/thesaurus/gujarat
[12] http://admin.indiaenvironmentportal.org.in/category/thesaurus/population