Kendrapara: Residential water birds have begun thronging the marshy wetland spots of Bhitarkanika National Park with onset of monsoon.

Thousand of winged species visit the heronry here every year for their annual nesting and breeding.

Water birds have begun arriving at the wetland sites in small groups.

"The arrival of local migrant birds has re-established Bhitarkanika as one of the prominent heronries of the state," said divisional forest officer, Rajnagar mangrove (wildlife) forest division, Prasanna Kumar Acharya.

"At present, the congregation of the birds is low. There will be larger gathering of migrant species at Bagagahana heronry for seasonal nesting as monsoon picks up pace. The birds build nests and lay eggs atop the mangrove trees. Their sojourn would last for three to four months from now after which they would start their homeward journey," he said.

The monsoon migrant birds are arriving in batches. "So far, around 10,000 local resident water birds have made their way to dense mangrove cover in Bagagahana," Acharya said.

Prominent species that are arriving here for nesting include Grey Heron, Purple Heron, Darter, Cormorant, Large Egret, Intermediary Egret and Little Egret.

Last year, 1,03,853 avian species were spotted here. A forest official said that the figure would rise this time.

The birds' habitat is spread across a stretch of around four-hectares. Their arrival have added to the scenic beauty in and around the water bodies.

There is ample food for the birds as the place has innumerable water inlets and nullahs that are free of human interference, said a forest official.

Lack of human interference, ideal climatic condition, cool breeze and the river system have emerged as prominent reasons for congregations of the birds.