Ranchi: Migratory birds have started to flock to the water bodies in the state, heralding the onset of winter and giving ample reason for birders to rejoice.

Though the trend of migratory birds in the state this year will be known only after January when their numbers become known, experts are delighted by the visual treat.

At Tilaiya Dam in Koderma, Indrajeet Samanta, a local bird expert and a member of Bombay Natural History Society (BNHS), said he had spotted a few blue-tailed bee eaters a couple of days back.

"At Lotwa reservoir, I could see common coot and ruddy shelduck," he said, adding that he will begin his annual bird exploration exercise along with his group soon.

Samanta said half-a-dozen winged guests arrived in Koderma in the last one week.

"Species such as bar-headed geese, northern pintail, osprey, common coot, red-crested pochard and ruddy shelduck have been spotted so far. A local migratory bird, black-headed ibis, were found in large numbers," he said, adding that the arrival of birds has happened on time this year.

Hazaribagh-based birder S.S. Goswami agreed. Goswami, who runs a club called Bird's Buddy that works for the cause of avian species, spotted bar-headed geese at Charwa Dam on Sunday.

"Last year, I spotted it on November 10, which means the birds have arrived on time. Till now, I recorded the white wagtail, white-browned wagtail, citrine wagtail, bar-headed geese and gadwall at Charwa Dam," he added.

Ranchi Lake and Kanke Dam are the favourite haunts of lesser whistling ducks.

Satya Prakash, state coordinator of Indian Bird Conservation Network, said the bird count and number of species were set to increase during the first two weeks of December.

"Usually, the birds arrive from Mongolia, Tibet, Himalayan regions and Central Asia," he said, adding that around 30,000-40,000 birds on an average are expected this time.

According to reports, around 70,000 birds were recorded in Asian Bird Survey 2015 during the migratory season. "Last year, we conducted surveys at around a dozen water bodies on behalf of the forest department and registered a little over 30,000 birds. But near every water body, problems of poaching, encroachment and ill-maintained wetlands continue to remain a concern," Prakash said.

Samanta said a double-decker motor boat introduced at Koderma Dam this year might distract the birds.