The Okhla bird Sanctury is often called an accidental sanctuary, a safe haven created by migratory birds for themselves on the Yamuna.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/sanctuary-chance-now-under-siege
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/times-india-new-delhi
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/uttar-pradesh
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/migratory-species
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/wildlife-act-1972
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/environmentalists
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/river-pollution
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/wildlife