One of the painted storks that remains in the zoo. (Bishwarup Dutta)

A baby painted stork has gone missing from its enclosure in Calcutta zoo, raising fresh questions about the vulnerability of inmates within nine weeks of the marmoset theft.

The Indian bird, which figures on the list of protected species with a “nearly threatened” conservation status, was last seen on Monday night on Hoolock Island, opposite the open-air tiger enclosure close to the main gate.

Kushal Mukherjee, an ornithologist, said the painted stork is “valuable” for its conservation status. “Though previously there were pockets of painted stork in the region, now only the Alipore zoo has a colony of 15-odd, pushing up its conservation value.”

Senior officials who inspected the enclosure on Tuesday morning blamed the disappearance on a civet, said a zoo keeper.

“But it is more likely that someone used this wooden plank (it was there when Metro visited the spot on Tuesday afternoon), to take the bird away,” he added on condition of anonymity.

Officially, however, mum was the word. “I have just joined today and know nothing about the incident yet,” said V.K. Yadav, who is in temporary charge with the zoo director on leave.

Deputy director Piyali Chatterjee went one step further by doubting that any painted stork had recently been born in the zoo.

“A temporary nest was constructed to house the baby stork and it was here till Monday evening,” pointed out a zoo keeper, rubbishing the official’s claim.