Alarmed by the sudden decline and near-disappearance of some bird species - like the common house sparrow - from the city, the Bombay Natural History Society (BNHS) is planning a study to find out
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/do-you-know-why-chirruping-has-stopped
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/indian-express-mumbai
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/wildlife