They are "Eyes in the Skies".
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/unmanned-drones-keep-watch-over-forests
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/times-india-chennai
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/tamil-nadu
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/national-tiger-conservation-authority
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/poaching
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/deforestation
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/wildlife