India, March 3 -- Due to the early onset of summer coupled with above-normal temperatures being reported since the beginning of January this year, bird watchers are experiencing a decline in the sighting of migratory bird species at popular spots across the city. Birds are leaving early this year which could be associated with rising temperatures and though it cannot be established as a trend, the pattern is there, said Ranjeet Rane, a city-based bird watcher and coordinator of the Great Backyard Bird Count initiative.

"The exact impact of increasing average annual temperatures on bird migration will need to be studied over the longer term. From the available data, we see a pattern this year that both the number of species and their indi...