"We have spotted birds of different species in the sanctuary," DFO(wildlife) B P Acharya said.
The wildlife division has taken steps to protect the feathered guests.
"We have set up camps in Nalabana to keep the birds away from poachers. More camps will be set up in other parts of the lake," the DFO said.
"We expect more birds to come in the days to come," he added.
Ornithologists felt that early snowfall and scarce food might have led the birds to migrate to Chilika.
"They start migrating when they face difficulty in getting food and to breed," noted ornithologist U N Dev said.
However, former chief conservator of forests Sudhakar Mohapatra felt that the abundance of food and favourable weather attracted birds to Chilika and they have not arrived early this year.
"They are on time this year," he said.