Thirty per cent of the avian guests, which had arrived here late this winter, have already left, Sub-divisional forest officer of Chilika wildlife division A K Patra said.
The birds generally flock to the lagoon during the second week of October and leave during the second week of March, at the onset of summer. This time they arrived about a month late in mid- November and started departure from the end of January, Patra said.
" Global warming might be the cause of their early return,"he said.
Sudden rise in the temperature and abnormal weather condition in the atmosphere are some of the reasons for their early return, U N Deo, a noted ornithologist said.
The migratory birds, mostly from palaearctic region beyond Himalayas like northern Eurasia, Caspian region, Siberia, Kazakh, Lake Baikal and remote places of Russia and neighbouring countries, visit the lagoon to escape the severe cold there.